Operator 1 chapter 9 ponds

When water elevation starts to drop look for these possible causes to water drop.

-Discharge valves open too far or a stop log is missing -levees leaking due to animal burrows cracks soil settlement or erosion - inlet lines plugged or restricted and causing wastewater to back up into collections ystem

Reasons to not maintain constant water levels at pond

-control shoreline aquatic vegetation - control mosquito breeding and burrowing rodents - handle fluctuating inflows - regulate discharge continous intermittent or seasonal

Shallow ponds

3-5 feet are often used to treat wastewater and other wastes instead of or ina edition to conventional waste treatment processes When discharged into ponds, wastes are stabilized by several natural processes that act in the same time Heavy solids settle to bottom where tehy decomposed by bacteria lighter suspended materials are broken down by bacteria in suspension and some wastewater is disposed of by evaporation from pond surface Dissolved nutrients like phosoprus and nitrogen are used by green algae,

Key considerations of duckweed system practice

30 day retention time shallow pond empty and frequent harvesting every 1-3 days at peak season if nutrient removal desired Plan must be in place for disposing of harvested plants Post aeration of effluent may be necessary to meet DO requirements Capability to draw effluent from several levels and thereby avoid high algal concentrations near water surface during discharge

PH of pond ideal

7.5 or higher Initially the pH of bottom slduge will be below 7 due to digestion of slduge but acid producing bacteria , if pH drop discharge to pond should be diverted to another pond or diluted with makeup water (water from another source) High pH essential to encourage balanced anaerobic fermentation of bottom sludge This high pH is indicative of high algal activity since removal of CO2from water in algal metabolism tends to keep pH high Low pH means acid production and will cause odors, soda ash may be added to influent to rise pH

Stop log

A log or board in an outlet box or device used to control the water level in ponds and also the flow from one pond to another pond or system.

Population Equivalent

A means of expressing the strength of organic material in wastewater. In domestic water system, microorganisms use up about .2 pound 90 grams fo oxygen per day for each person using thes ystem as measured by standard BOD test, may also be expressed as flow 100 gallons per day per person or suspended solids .2 lbs per day per person Population equivalent in person = Flow MGD X BOD mg/l X 8.34 lbs/gallon / .2 lb BOD per day per person

Chemical Oxygen Demand (COD)

A measure of the oxygen required to oxidize all compounds, both organic matter in water. Expressed as amount of oxygen consumed from a chemical oxidant or mg/L during a specific test results are not necessarily related to BOD cause chemical oxidant may react with substances taht bacteria do not stabilize

Pond uses may be classified according to detention time

A pond with less than three days detention time treat water in wasps simliar to sedimentation or settling tank with some growth of algae but not have a major effect on treatment of wastewater Abundant growth of algae wil be observed in periods of 3-20 days detention times, with large amounts of algae in pond effluent, stored organic material may be greater than the amount in the influent in some cases for this Effluent BOD will show considerable reductions than influent BOD but this is because BOD is a rate estimate (oxygen used in 5 day period, the rate of oxygen use is temporarily slowed down but will increase when anaerobic decomposition of settled dead algal cells starts Longer detention times give time fro sedimentation of algae, occurs in facultative ponds having anaerobic conditions on bottom and aerobic conditions on the surface, combined aerobic anaerobic treatment provided by long detention times produce definite stabilization of pond influent during treatment in pond

Duckweed

A small, green, cloverleaf-shaped floating plant, about one-quarter inch (6 mm) across, which appears as a grainy layer on the surface of a pond.

Splash pad

A structure made of concrete or other durable material to protect bare soil from erosion by splashing or falling water.

Silt deformation

Aeration tube slits may be allowed tod form by shutting off the air once a day for about 20 minutes. Weight of water above the tubing will causee slits to deform inward breaking up deposits

Platform aerator components and parts and purpose

Aerator- introduce oxygen to pond Electric motor- provides energy to drive aerator Drive reduction gear box- converts torque from motor to drive impeller Draft tube- conveys bottom contents of pond to surface for aeration Discharge guide- regulates spray patterns for oxygen transfer to water Jacking screw- adjusts aerator impeller level in water to regulate oxygen transfer and motor loading amps

Alkalinity testing

After determining normal alkalinity levels for pond, sudden change in alkalinity of 10-20 percent mg/l or more indicate problem is developing Change in alkalinity may be wanting taht pH of pond could change in a day or two if corrective action not done Trends in alkalinity continues in one direction for two or three days, cause of cahnge should be identified Useful results alkalinity test should be performed every day

Methane fermentation

All organic matter ends up at bottom of stabilization pond through process of sludge decomposition, and is subject to methane fermentation, in order for methane fermentation to exist, abundance of organic matter must be deposited and continually converted to organic acids. An abundant population of methane bacteria must be present tehy require pH of 6.5-7.5 within sludge alkalinity of several hundred mg/l to neutralize organic acids, and suitable temerpatures Once methane fermentation occurs it is considerable amount of organic load removal

Pond depth of 4 feet or more

Allow greater conservation of heat from incoming wastes Encourages bio activity In facultative ponds, depth over four feet provide physical storage for dissolved oxygen accumulated during day, stored dissolved oxygen carries over through night when no oxygen is released by algae Physical storage of DO is important during colder months when night is long Pond depth of atelast 3 feet is recommended to prevent tule and cattail growth weeds emerge along shoreline can be effectively controlled by spraying several products and ponds designed to be less than 3 feet should be lined to prevent troublesome weed growth

Crowning levee tops

Allows rainwater to drain over the side in a sheet flow, otherwise rain may flow a considerable distance along the levee crown and gather enough flow to cause erosion when it spills over side and down slope If levees are used as roadways during wet weather tehy should be paved or well traveled, if seepage or leakage from pond appears on outside of levees, ask engineer to investigate and solve problem before further damage occurs

Overturn

Almost spontaneous mixing of all layers fo water in reservoir or lake when water temperature becomes similar from top to bottom, this may occur in the fall winter when surface waters cool to same temperature as bottom waters and also in the spring when surface waters warm after ice melts,

Advanced waste treatment

Any process of water renovation that upgrades treated wastewater to meet specific reuse requirements may include general cleanup of water, or removal of specific parts of wastes insufficently removed by conventional means can include chemical treatment or pressure filtration also called tertiary treatment

Algal blooms

Appear 7-12 days after wastes are introduced into pond Takes atleast 60 days to establish thriving biological community, definite green color is evidence of flourishing algal population. Bacterial decomposition of bottom solids sets in after algal population is established, and evidenced by bubbles coming to surface near the pond inlet where most slduge deposits occur, traveling of gas from anaerobic layer to aerobic surface layers prevents odor releases W

Chironomid midges

Are often produced in ponds in sufficient numbers to be serious nuisances to nearby residential areas farm workers recreation sites and industrial plants. Can also create traffic hazards in large numbers Only satisfactory control is through insecticides Control is time consuming and difficult, especially if they are discharging to receiving stream. If possible lower the level i ponds enough to contain a days inflow before applying an insecticide. Holding insecticide for atleast one day will kill more insects and reduce effect of the insecticide on recieving waters, they should be applied on a calm day and any recirculation pump should be stopped

Pond area formula

Average pond area (acre)= average width ft X average length ft / 43,560 square ft/acre

Expected treatment efficiencies of pond

BOD 50-90 percent BOD facultative pond detention time 50-60 days 70-90 percent Coliform bacteria facultative pond detention time 50-60 days 90-95 percent SS detention time after 3 days 90 percent Dissolved organic solids after 10 days detention time 80%

BOD testing on ponds by time frame

BOD should be measured on weekly basis. Samples taken during day at low flow, medium flow and high flow should be done through day Then average of three tests will give reasonable indication of organic load of water being treated. If BOD varies sharply during day or from day to day, or unusual circumstances exist, sampling frequency can be increased to obtain clear definition of variations. If pond DO is supersaturated, the sample must be aerated to remove excess oxygen before BOD test is performed.

Screening

Be sure to clean bar screen frequently as necessary and inspect screen atleast once or twice a day More frequently during storm periods. Screenings disposed in sanitary manner. Like burial to avoid odors and fly breeding Can also place screenings in garbage cans adn request local garbage service dispose of screenings in sanitary landfill Many ponds have grit chambers at headworks to protect raw water lift pumps and prevent plugging of influent lines Many types of grit removal equipment girt removed by various means will usually contain small amounts of organic matter and therefore be disposed of in a sanitary manner, most common is burial

Surface aerators uses

Been used in two applications - provide additional air to ponds during the night or cold weather or for overloaded ponds - provide a mechanical aeration device for ponds operating as aerated lagoons, aerated lagoons operate like activated sludge aeration tanks without returning any settled activated sludge In both cases aerators ar operated b y time clocks and established on off cycles. Lab tests on DO indicate time period for on and off cycles to maintain aerobic conditions in surface layers of pond Adjustments are done when quantity or quality of influent changes or from seasonal weather conditions

Blow outs

Blowouts of aeration tubings dn boils caused by slit enlargement must be repaired, damaged area must be cut outa nd special coupling inserted and clamped into place Lagoon water level may need to be lowered so line can be hooked up and drawn to surface for repair

Riprap

Broken stones, boulders, or other materials placed compactly or irregularly on levees or dikes for the protection of earth surfaces against the erosive action of waves.

Weeds pulled should be

Buried to prevent odor and insect problems Use buddy system when pulling weeds to prevent someone drowning from being stuck in a clay liner, and approved flotation devices are necessary as well,

Keeping levees and dikes in good condition

Can be timesaving activity, regularly inspect levees for leaks and erosion and correct immediately. If erosion is problem at waterline install rip rap Do not allow weeds to grow along waterline andd keep weeds on levees mowed If insect larvae are on pond surface spray with appropraite insecticide

Heavy chlorination and odor

Can help fight odor control but impacts treatment process

Chemistry of waste

Can waste be treated where pond is located? Toxic constituent stay interfere with growth of algae or bacteria certain wastes like dairy products and wind products are difficult to treat because of low pH Any processing waste must be investigated before it can be certain if ponding can treat it Some wastes contain fungicides and disinfectants taht inhibit effect of biological activity in pond Other wastes may have nutrient difficiencies Some natural water supply have high sulfur content or chemicals that limit possiblity of desired sludge decomposition

Safety

Catwalks should have gaurdrails and non-skid surfaces

Aerobic ponds

Characterized by having dissolved oxygen distributed throughout thier contents practically all the time, usually require additional source of oxygen to supplement rather minimal amount that can be diffused from atmosphere at water surface May be supplied by algae during daylight or mechanical agitation or compressors bubbling air through pond

If pH and DO drop

Check loading May need to be reduced or stopped Recirculating water from healthy pond to problem pond can help as well Recirculation from outlet to inlet areas can also be beneficial for seeding DO and mixing Changes take time to appear often until a week or so after changes made

Before applying insecticide or herbicide

Check with appropriate authorities regarding long term effects of pesticide you plan to use Do not apply pesticides taht may be toxic to organisms in recieving waters

Scum control

Common characteristic of ponds are scum accumulation, usually greatest in spring when water warms a nd biological activity resumes, wind action will break up scum accumulations and cause them to settle, but in absence of wind or sheltered areas, scum must be broken up by other means If scum is not broken, it will dry o top and become crusted, making it harder to break up and species of blue green algae is about to become established on the scum, this can cause odors and block sunlight into pond Rafts of scum cause unsightly appearance, can quite likely become source of botulism taht will have devastating effect on waterfowl and shore birds attracted to facility Agitation with garden rakes forms hore, jets of water from pumps ro tank trucks, and use of outboard motors can all break up scum Airboard motors should be air cooled type to prevent plugging the cooling system with aglae and scum

Controlled discharge

Common operational modification to aerated and facultative ponds is controlled discharge mode where pond discharge is prohibited during winter months and cold climates or during peak algal growth periods in all climates, each cell in system is isolated and then discharged sequentially, sufficient storage capacity is provided in lagoon systems to allow wastewater storage during winter months, peak algal growth periods, and recieving stream low flow periods Most discharges occur in spring or fall where discharge effects on water quality impact are minimized Secondary benefit is operational costs are lower tahn for continous discharge lagoon because of reduction in lab monitoring requirements and need for less operator control

Oxidation ponds

Commonly ponds ar used in series after primary wastewater treatment plant to provide additional clarification BOD removal, and disinfection Ponds in series can provide high quality effluent taht is acceptable for discharge into many watercourses If detention time long enough then many ponds can meet fecal coliform standards Go influent primary clarifier then pond 1 to pond 2

Outlet structures

Consists of baffled and submerged pipe inlet to prevent scum and other floating surface material from leaving pond Level of pond and rate of outlfow can be controlled by use of flash boards in outlet structures Rowboats can be used toa ccess outlet baffle Avoid valves with stems extending into stream flow as stringy material and rags will collect and form obstruction and render valve inoperative Free overfalls at outlet should be avoided to minimize odors foaming adn gas entrapment which can hamper pipe flows If pond has surface outlet, you can keep floating material out of effluent by buidiliing simple baffle around outlet Constructed from wood or other suitable material

Duckweed

Consists of tiny green plants that float on surface of pond, duckweed stops sunlight penetration and hinders surface aeration. Rakes water sprays ro pushigna. Board with a boat can be used to move duckweed into a corner of one wher eit can be physically removed from pond. You can install surface discharge in downwind corner of pond prevailing wind will blow duckweed into corner and duckweed will be removed by surface discharge. Duckweed captured in wire mesh bucket will need to be removed and cleaned as duckweed accumulates. The fact that duckweed prevents sunlight can actually assist the process in polishing ponds,

Before using insecticide

Contact local official in charge of approving pesticide applications

Anaerobic ponds coverage

Covered and isolated for odor control and followed by aerobic ponds Floating polystyrene planks can be used to cover pond and be painted white to protect against sun This helps confine odors and heat and tend to make anaerobic ponds more efficient

Pond is not working when

Creates visual or odor nuisance leaves high BOD, solids, grease, or coliform bacteria concentration in the discharge, unles sit was designed to be anaerobic in first stages and aerobic in later ponds for final treatment

Observe and test pond conditions

Daily visual observations with pond having green deep color indicate good aglae population Scum and floating weeds should be removed to allow sunlight to reach algae in pond Once or twice a week tests for DO pH temperature should be done Effluent dissolved oxygen should be measured as well. Other effluent tests done at least weekly are BOD suspended solids dissolved solids, coliform bacteria, and chlorine residual If pond is operated as batch only test effluent during periods of discharge

Pond detention time formula

Detention time (days) = Pond Volume (acre ft) / influent flow rate (acre ft per day) Does not account water lossed to evaporation or percolation May vary from 30-120 days Minimum detention time of 180 days

When water surface rises look for

Discharge valve closed or lines plugged

Waste discharging pattern

Discharged intermittently during first few weeks with monitoring pH Pond kept at 7.5 or higher if possible

Advantages of a pond

Do not require expensive equipment Does not require highly trained operating personnel Is economical to construct Provides treatment taht is equal or superior to some conventional processes Is satisfactory way of treating wastewater on temporary basis Isa daptable to changing loads Is adaptable to land application Consumes little energy Serves as wildlife habitat Has increased potential design life Has few slduge handling and disposal problems Probably most trouble free treatment process

Grab samples

Done for temperature pH DO and chlorine residual Is a single sample Test must be immediately after sample is collected in order to obtain accurate results Composite samples best measure Composite samples should be placed in refrigerator or ice chest as soon as possible after they are collected. BOD and SS are measured using composite samples

Algae population throughout year

During summer months, suspended solids test spikes because algae population spikes in warmth, then drops in winter when its colder, arid locations tend to have evaporation rates high enough to evaporate water from pond at rate to no effluent released, preventing release of high SS effluent

Ponds individuality

Each biological community is unique. Ponds with same influent and same amount often ahve different pH and DO content as any given time One may have more scum than the other Each pond needs its own routine tests for pH and DO Testing may indicate unequal loading because of internal clogging of influent or distribution lines that may not be apparent visually. Tests can also indicate differences or problems taht are being created by buildup of solids or solids recycling Sparkling deep green color in pond indicates high pH and satisfactory dissolved oxygen content while ponds that turn dull green gray or colorless generally pH and DO have dropped too low can be caused by overloading or lack of circulation

Key considerations for HCRL

Effluent release model keyed to flow as measured by depth, in receiving stream is needed Outlets should be capable of drawing from different depths to ensure best quality Storage cells should be sized by use of water balance equations

Types of surface aerators and maintenance

Either stationary or floating Maintenance conducted in accordance to manufacturers specs. Always lock tag out when repairing equipment Overhead guy wires have been used to prevent aerators from turning over when iced up If power failure occurs for short time pond surface will freeze rapidly and possible mechanical damage will occur. If aeration stem becomes plugged by deposits of carbonate try reducing aeration or adding CO2 gas. Ponds can also be aerated by air compressors connected to plastic tubes with holes drilled into them are layed and thenplaced across pond bottom. Diffusers can become plugged and cause maintenance problems

Controlled discharge ponds

Facultative ponds with long detention times up to 180 days or longer, these ponds may discharge effluent only once fall or twice fall and spring a year

Critical periods of pond life

First placed in operation At least one foot of rest water should be in pond before wastes are introduced, water should be turned into pond in advance to prevent odors developing from waste solids exposed to atmosphere thus source fresh water should be available when starting a pond

Conversion of flow rate in gallons per day to acre feet per day

Flow rate (acre feet / day) = 200,000 (gallons per day) X (1/7.48) cubic feet per gallon X (1/43,560) acres per square feet

Purpose of pond and parts

Flowmeter- measures and records flow into pond Bar screen- removes coarse material from pond influent Pond inlets- distribute influent to pond Pond depth and outlet control- regulates outflow from pond and depth of water in pond allows pond to be drained for cleaning and inspection Outlet baffle- prevents scum and other surface debris from flowing to next pond or receiving waters Dike or levee- separates ponds and holds wastewater being treated from ponds Transfer line- conveys water from one pond to another Recirculation line- returns pond effluent rich in algae and oxygen from second pond to first pond for seeding dilution and process control Chlorination- applies chlorine to treated water for disinfection Chlorine contact basin- provides contact time for chlorine to disinfect pond effluent Effluent line- conveys treated wastewater to receiving waters to point of reuse irrigation or to land disposal site

Frequency and location of lab samples

Frequency and expected ranges vary from pond to pond but establishing those ranges within the pond help it funciton properly Test results will vary during hours of day Samples should always be collected from same point. Or location. Raw water samples for pond influent should be collected near wet well of influent pump station ro at inlet control structure Samples of pond effluent should be collected from outlet control structure or from well mixed point in outfall channel Pond samples Amy be taken from the four corners of pond Samples should be collected from point eight feet out from waters edge and one foot below water surface Try not to stir up material from pond bottom Do not collect samples during or immediately after high winds or storms because solid will be stirred up after these activities

Aeration tubing effective maintenance program

Gas cleaning- some require cleaning on weekly basis with anhydrous hydrogen chloride gas, gas removes deposits on the tubing slits and destroys biological slime that may grow in tubing. Deposits are caused by precipitation of carbonate and bicarbonate compounds

Variation in ponds

Great amount of variation through depth, operating conditions, and loadings,

Anhydrous hydrogen chloride gas

HCI is extremely dangerous Stand upwind from HCI tank high concentrations of hydrogen chloride gas can be corrosive to eyes skin and mucus membranes. If system uses central manifolds, you must be cautious of HCI gas accumulating in low areas. HCI. gas is 1.3 times heavier than air. Also the needle valve must be closed prior to opening the cylinder valve. Installation of a pressure regulator between needle valve and cylinder valve will minimize potential excess pressure development. HCI reacts with metals to form flammable gas hydrogen. All materials used in manifold header transport and regulation systems must be compatabile with HCI If potential for exposure to HCI exits you must use appropraite breathing protection, cold insulating gloves, protective clothing, and face shield or eye protection

Hydrograph controlled release lagoon

HCRL water is retained in pond until flow volumes and conditions in receiving stream are adequate for discharge, thus eliminating the need for costly additional treatment Has three principal components Stream flow monitoring system Storage cell Effluent discharge system Stream flow monitoring system measures flow rate in the stream and transmits data to effluent discharge system, effluent discharge system constitutes of controller and discharge structure, controller operates a discharge device such as motor driven sluice gate, through which wastewater is discharged from storage lagoon however these tasks can be manually performed

Headworks and screening considerations

Have bar screen installed Trash shredder is luxury that may not be warranted, any material taht gets past an adequate bar screen will not harm influent pump most likely, any fecal matter are pulverized when going through pump

Constructed wetlands

Higher levels of effluent quality desired, you can build constructed wetlands , Two types Free water surface Subsurface flow system Free water surface system consists of basins or channels with a natural or constructed subsurface barrier of clay or impervious material taht prevents seepage from wetland Soil sand gravel and rock or another suitable material is used to support emergent vegetation and water is maintained at shallow depth flowing over the surface Subsurface flow wetland is constructed as a trench or bed with impermeable layer of clay or synthetic liner Bed contains media of rock gravel or soil that will support growth of emergent vegetation Wetland bed is constructed with slight slope between inlet and outlet end Influent is applied to wetland at high end and permitted to flow under media surface through media and plant roots to outlet end where it is collected and discharged.

Hydrogen sulfide in ponds anaerobic

Hydrogen sulfide is normally not a problem inn properly designed and operated ponds, because it dissociates into hydrogen and hydrosulfide ions at high pH and may form insoluble metallic sulfide or sulfates , this high dissipation and formation of insoluble metallic sulfide is the reason ponds having a pH of 8.5 do not emit odors, even when hydrogen sulfide is present in relatively large amounts, exceptions occur in northern climates during spring when pH is low and pond is just getting started, then they are problem

Aerator operation rule

If pond has foam on the surface, reduce the operating time of aerator, and fi no evidence fo foam on pod surface, increase the operating time of aerator Trace of foam on surface is satisfactory aeration

Hydraulic loading pond formula given detention time

Inches per day = depth of pond (inch) / Detention time (days)

Hydraulic loading Overflow rate pond formula

Inches per day = inflow (acre inch per day) / average pond area (acres)

Large amounts of brown or black scum

Indication pond is overloaded Scum on surface of pond often leads to odor problems

Minute shrimp like animals

Infest pond from time to time during warmer months of year march to november, microcrustaceans live on algae at times will appear in numbers as to almost clear the pond of algae, during severe infestations there will be sharp drop in DO of pond accompanied by lower pH, this is temporary condition as the crustaceans will outrun alagal supply, and there will be a mass die off of insects, which will be followed by a rapid greening up of pond again When algal concentration in pond is Low under these conditions, ponds operate on a batch basis may find this as a good time to release water due to low suspended solids values. Ordinarily there is no concern about these infestations because tehy soon balance themselves, but in heavily loaded pond, sustained low DO can give rise to obnoxious odors, in this event, any several commercial sprays can be used to control shrimp like animals

Flow measuring devices

Influent measure device should be installed to know daily volume of wastes introduced into pond Along with BOD measurement of influent is required to estimate the organic loading on pond Comparing influent vs effluent flow rates are also necessary to estimate percolation and evaporation losses Flow measuring device can collect data needed to detmerine future plant expansion needs or see unauthorized or abnormal flow patterns well kept records on volumes must be kept

Inlet and outlet structures

Inlet are simple foolproof constructed of standard manufactured articles so replacement parts are readily available Telescoping friction fit tubes for regulating spill or discharge height should be avoided because a biological growth can become attached and prevent the tubes from telescoping if they are not cleaned regularly Occasional hypochlorite solution can be effective in discouraging growths Ice can prevent adjustment of tubes Place polyethylene floating ring sprayed with urea around friction tube of telescopic valve to prevent freeze ups Acts like floating baffle to keep scum and floating debris from clogging up tube

Suspended vegetation control measures

Keep pond exposed to clean sweep of wind Few ducks may be used to eat light growth of duckweed Small ponds may be skimmed with rakes or boards this may have to be repeated Excessive growth can be mechanically harvested Use herbicide as last resort

Control measures for weeds

Keep water level above three feet Pull out new growth by hand Drown the weeds by raising water level Lower the water level cut the weeds or burn them with gas burner, raise water level (cut and drown Use herbicide as last resort Use RIPRAP along the bank, if riprap is used and growth continues herbicides are alternative Install a pond liner

Fencing and signs

Keeps livestock out of pond and discourage trespassing Gate wide enough for mowing equipment and other maintenance vehicles to enter the pond facility should e provided Signs should be posted along fence around pond to indicate nature of facility adn forbid trespassing the signs should not be more tahn 300 feet apart but spacing should comply with local penal codes governing trespass

Recirculation rates

Large amounts of 25-100 percent can be helpful, allow algae and other aerobic organisms to thoroughly mix with incoming raw wastewater, at same time, good oxygen transfer can be attained by passing incoming water over a deck and down steps or other types of aerator and this procedure can cause heatloss as a disadvantage

Herbicide use

Last resort because of obvious hazards facing operator but also dangers presented to biological growth of pond and recieving stream Care must be taken to follow mixing application and storage directions exactly, safety to operator and any persons who might contact with herbicide is utmost importance. Proper protective gear and warnings verbal and written are vital Do not use stored herbicides without checking on thier current status of approval as federal clearance ad state registration of herbicides may change Some herbicides only work on certain plants, Most important factor in herbicide selection is site compatibility. Check that our site is on comprehensive list of approved application sites provided by herbicide producer.

Levee maintenance

Levee slope erosion caused by wave action or surface runoff from precipitation is probably most serious maintenance problem If continues, it will result in narrowing of levee crown which will make accessibility with maintenance equipment most difficult If composed of easily erodible materia, one long range solution is the use of bank protection materials including small pieces of broken stree materials or stone riprap or broken concrete rubble. Curbs gutters bricks from building demolition can work too. Semi-porous plastic sheet has been used with riprap which allows two way movement of air and water, prevents movement of soils.also discourages weed growth and digging by crayfish Geosyntehtic products are effective means of erosion control.

Suspended vegetation weeds

Like duckweed, usually will not flourish if pond is exposed to clean sweep of wind, dike vexation control is aided by regualr mowing and use of cover grasstaht will crowd out undesirable growth Emergency weed growth only occurs when sunlight is able to reach pond bottom, best prevention measure agaisnt growth is to maintain a water depth of at least 3 feet, with greater water clarity, amount of sunlight reaching bottom will be greater in secondary or final ponds, shallow water promotes growth so there will always be a battle to keep emergency weeds from establishing around lagoon banks

Long root plants

Like willows and alfalfa should not be allowed to grow on levees, tehy damage levees adn cause levee failure and costly repair Burrowing animas like muskrats badgers squirrels and gophers also may cause levees to fail remove these animals as soon as possible and repair burrowed holes immeditealy

Algae in effluent

Little operator can do to change to effectively remove algae in effluent, best approach is to operate ponds in series and draw off effluent below the surface by use of a good baffling arrangement If it must be removed from effleunt, additional facilities will need to be designed and constructed Algae removal processes include micro screening, slow sand filtration, dissolved air flotation and algae harvesting In final ponds operated in series with periodic discharges alum Amy be added in doses of less than 20 mg/l to improve effluent quality before discharge Do not over chlorinate the effluent when high levels of algae are present, will cause algae to explode break up making effleunt more difficult to disinfect, also dead algae increase BOD in effluent

Plant grass

Low growing spreading grass should be planted where portions of pond levee or dike are not exposed to wave action. Native grasses may naturally seed the levees or local highway departments may be consulted for suitable grasses to control erosion Do not allow grazing animals to control vegetation because they may damage levees near waterline or complicate erosion problems, but you can mow if it gets too high

Straw

Many different species of algae Field studies show that barley straw can be effective in controlling blue green algae that blocks light and kills algae Decomposition of barley straw releases active agent that kills this blue-green algae Wheat straw can work as well, but barley is better Straw sould be applied to final water stabilization pond twice a year, once in autumn a dn again in spring before algal growth starts Application are about 77 pounds fo straw per million gallons of water in pond Foot pond that is 20-50 feet would need about 2 pounds of straw more fi water in pond changes quickly a dose of 5 grams of straw per cubic meter is also suggested Water quality indicators should be monitored to ensure desired performance of straw Can also help reduce total suspended solids in effluent

Pond contradiction and factors for practicality installation of one

Many think pond treatment efficiency is best when no odors are present, but actually greatest organic laod destroyed per unit of area or highest treatment efficiency is often accompanied by odors Ponding offers many advantages in small installations Only true providing land is not costly ad location is isolated from residential commercial or recreational areas

Limitations of ponds

May produce odors Requires large area of land Treated wastes inconsistently depending on climatic conditions May contaminate groundwaters May leave high levels of suspended solids in effluent

Measuring quality indicators

Measure water indicators like DO and solids frequent regular intervals and plot them to have some idea on direction process is taking in time to take corrective action if necessary

Algae

Microscopic plants containing chlorophyll that live floating or suspended in water, excess algal growths can impart taste and odor into water, algae produce oxygen during sunlight and use oxygen during night hours, biological activity of algae affect pH alkalinity and DO in water

Submerged inlet

Minimizes occurance of floating material and will help conserve heat of pond introducing warmer wastewater below surface

Free oxygen

Molecular oxygen available for respiration by organisms, molecular oxygen is O2 that is not combined with another element or compound

Facultative ponds

Most common type fo pond inn current use, upper portion of supernatant is aerobic while bottom of pond is anaerobic, algae supply most of oxygen to supernatant near the top of water, almost impossible to maintain completely aerobic or anaerobic conditions all the time at all depths of a pond

Facultative pond

Most common type of pond in current use, upper portion supernatant is aerobic, while bottom layer is anaerobic algae supply most of the oxygen to supernatant

Dike vegetation control

Mow regularly during growing season. Dike slopes may be cut using sickle bars or weed eater equipment Any tractor used on slope should have low center of gravity and equipped with approved roll over protective structure and seatbelts with certain use/weight classifications Seed or reseed slopes with desirable grasses that will form thick and somewhat impenetrable mat Use herbicide as last resort

Estimating organic loading

Must ofknowledge of BOD ofwaste and approximate average daily flows influent BOD and solid will vary with time of day day of week and season but pond is good equalizer if not overloaded

Population loading

Number of persons per acre = population served (person) / surface area of pond (acres)

Abnormal operation of ponds

Occurs when pond overloaded and cause BOD loads to be too high. Excessive BOD loads occur when influent loads exceed design capacity due to population increases, industrial growth, or industrial dumps, New facilities must be constructed or the BOD reduced at the source, repeated wide fluctuations in BOD loads over short time period will also interfere with pond performance and create nearly constant state of abnormal operation

Second type of overloading

Occurs when too much flow is diverted to one pond, happens when operator accidentally feeds one pond more than the other or when pipe opening is blocked by rags solids or grid due to low pipe velocities, when this happens odors are produced, take pond out of service so it will not become overloaded excessively, remove rags solids or grit that caused overloading and inspect the other pipes to prevent this problem from happening again in other ponds Usually ponds do not become overloaded during storms and periods of high runoff because there is not a significant increase in BOD loadings on the ponds

Odor control

Odors will result from wastewater treatment plant no matter what kind of process is used Most odors caused by overloading or poor housekeeping practices If overloaded stop loading adn divert influent to other ponds, then gradually start loading the pond again once loading drops, once a pond develops odor problems it is more apt to cause trouble than other ponds Unexpected shutdowns occur, plant processes may be upset and cause odors Strongly advised that a careful plan for emergency odor control be available Odors occur during spring warm-up in colder climate because biological activity has been reduced during cold weather, when water warms microorganisms become active use up available dissolved oxygen, and odors are produced under these anaerobic conditions

Valves open vs closed

Ope to many inlet valves slow velocities to point of settling So only have few valves open and clsoe all but one valve to get good velocity Or recycle pond effluent to increase volume of water

Organic loading pond formula

Organic load lbs BOD/day/acre = BOD (mg/l) X Flow (MGD) X 8.34 (lbs/gallon) / pond area (acre)

Pond treatment efficiencies chemical factors

Organic material PH Solids Concentration and nature of waste

Aerobic ponds and aerobic layer of facultative ponds treatment process

Organic matter contained in water is first converted to carbon dioxide and ammonia then to algae in presence of sunlight Algae are simple one or may felled plants that are essential to successful operation of aerobic and facultative ponds By using sunlight for energy of photosynthesis, algae use carbon dioxide in water to produce free oxygen Making it available to aerobic bacteria that inhabit pond Each pound fo algae produce 1.6 pounds fo oxygen on normal summer day, algae live on CO2 and other nutrients in wastewater and at night light no longer available for photosynthesis so algae use up oxygen by respiration and produce carbon dioxide instead This causes diurnal or daily variations in both pH and dissolved oxygen by changing of process of respiration dependent on daylight When algae use CO2 pH rises, and at night they rpoduce CO2 and pH lowers, algae are found in soil water and air and occur naturally in pond without seeding and multiply greatly under favaorable conditions

Anaerobic ponds treatment process

Organic matter is converted by group of organisms called acid producers to carbon dioxide, nitrogen and organic acids, at same time, a group called methane fermenters break down the acids and other products of first group to form methane gas and alkalinity, Water is another end product of organic decomposition This all occurs on bottom layers During certain times sludge decomposition in anaerobic zone is interrupted and it begins to accumulate, it is probably do to lack of right bacteria low pH or presence of substances taht slow or stop the process, or low temperatures. Under these conditions, acid production will continue at slower rate and rate of gas methane production slows down considerably Slduge storage in ponds is continous with small amounts stored during warm weather and large amounts when its cold, at low temperatures, bacteria cannot grow fast enough to handle waste, then in warm weather acid producers begin to decompose the accumulated sludge deposits built up during winter, if organic acid production is too great, lowered pH occur with possibilities to upset pond ad result in hydrogen sulfide odors

Duckweed system

Patented process uses aquatic duckweed plants for waster treatment Used in polishing pond after conventional treatment pond Duckweed on polishing pond surface prevents penetration of sunlight and causes algae to die and settle out of water being treated. Plastic grids 10-10 feet are. Placed on surface of pond to prevent wind from blowing duckweed to one side of pond Duckweed must be harvested regular basis for system to be effective Duckweed plaint are capable fo removing phosphorus and nitrogen from ater With enough detention time greater than 30 days, intensive harvesting significant nutrient removal can be achieved Duckweed needs water temp of 50F or greater

Winter conditions

Pond becomes covered with ice or snow, sunlight no longer available to algae and oxygen cannot enter water from atmosphere, without DO for aerobic decomposition, anaerobic decomposition takes place slowly due to low temp. Keeping pond surface at higher level can keep a higher detentio time and keep heat losses minimal, during snow cover or ice cover periods, odorous gases formed by anaerobic decomposition accumulate under ice adn are dissolved into wastewater being treated Some odors are present in spring just after ice cover breaks because pond is still in anaerobic state and some fo these dissolved gases are being released. Melting of ice in spring provides dilution water with high O2 content making pond facultative in few days after breakup of ice if not organically overloaded BOD

Pond volume formula

Pond volume (acre feet) = average area (acre) X depth (ft)

Raw wastewater lagoons or stabilization ponds

Ponds designs to treat wastewater with no prior treatment Requires sizable amounts of area

Pond in series vs parallel

Ponds in series tend to cause first pond to become overloaded and may never allow it to recover Go in parallel allows distribution of incoming laoad evenly between units Should depend on loading situation and NPDES permit requirements for type of pond setup

Shallow pond depth

Ponds of less than 3 feet may be complete aerobic if there are no solids on bottom because depth of light penetration Ponds this shallow with short detention times will have irregular performance as all waste is treated by converting it to algal cell material Algal blooms will increase to proportions that mass die off will occur, and algae sink to bottom and add to organic load, which leads to creation of anaerobic ponds Discharge from shallow aerobic ponds contain large amounts of algae Must have means of removing algae grown in pond before effluent is discharged to receiving waters if algae not removed, organic matter in wastewater is not removed or treated and problem merely transferred down stream Shallow secondary ponds lightly loaded tend to become infested with filamentous algae and mosses that not only limit penetration of sunlight into pond but hamper recirculation of ponds contents and clog inlet and outlet structures when loading increased, condition improves because algae and moss require relatively clean water with little nutrients to grow

Batch operation

Ponds operated only discharge once or twice fall or fall and spring a year Discharges are made only when necessary and if possible during non recreational season when flows are high in recieving waters If pond is allowed to discharge intermittently, you must work close with pollution control agency and be sure that you are in compliance with NPDES take samples before and during discharge as well as samples taken from receiving waters both upstream and downstream from point of discharge for analysis of DO BOD pH total suspended solids and coliform group bacteria

Floating aerator components parts and purpose

Pontoons or floats- provide platform for motor Guy wires- maintain aerator positions in ponds and anchor to pond levee Power cables- conveys power to motors Impeller aerator- pumps water into air to be aerated

Eliminating algae from effluent

Present in effleunt from ponds with continous discharge Causes loss of aesthetic values, increased turbidity suspended solids biochemical oxygen demand , also development of nuisance conditions Algae in effluent increase SS concentration to point that NPDES effluent limitation is exceeded Methods to remove algae have not reached acceptance due to increased treatment cost associated with processes, like centrifuges, chemcial coagulation filtration microsctraining magnetic separation and ultrafiltration

Pulling weeds PPE

Protective gear like waterproof gloves, boots a dn goggles should be worn to reduce chance of infection from pathogenstaht may be present in water,

Ways to reduce odors

Recirculation from aerobic units, use fo floating aerators, heavy chlorination Recirculation from aerobic pond to the inlet of anaerobic pond (1 part recycle flow to 6 parts influent flow) will recur or eliminate odors. Usually floating aeration and chlorination equipment are too expensive to have standing idle waiting for an odor problem to develop Odor masking ecmaisl also have been promoted for this purpose, and have some uses for concentrated sources of specific odors, however in almost all cases, process procedures of the type mentioned previously are preferable Poor procedure to wait until the emergency arises to plan odor control Several days ar needed to recieve delivery of materials or chemicals if they are required Sodium nitrate can be added to ponds as a source of oxygen for microorganisms rather tahn sulfate compounds thus preventing odors To be effective sodium nitrate must be dispersed throughout the water in the pond, once mixed in the pond, it acts very quickly because common organisms may use oxygen in nitrate compounds instead of dissolved oxygen, amount of sodium nitrate depends on oxygen demand, some operators dosed their ponds successfully between .3-.4 mg/L of sodium nitrate, liquid sodium hypochlorate or chlorine solution is faster acting solution, but will interfere with biological stabilization of wastes A different odor control strategy will be needed if ponds ahve already frozen over in winter but are expected to develop odor problems when the ice thaws in the spring and the water in the pond turns over Some operators spread sodium nitrate on ice surface before thaw so taht the chemical will be available to supply oxygen as needed

Pond detention times determined by

Regulatory agencies to ensure adequate treatment and removal of pathogenic bacteria Many agencies specify effluent or recieving water quality standards in terms of median and maximum most probable number values that should not be exceeded In critical water use areas chlorination or other means of disinfection can be used to further reduce coliform levels

Sampling and analysis importance

Routine pH and DO analysis are easiest that can be done by operator Measure pH temp DO in pond several times a week. Done several times a week and Occasionally during the night, indicate status and health of pond whether corrective action is necessary Record values for records. Time of day should be varied occasionally for tests. PH and DO tend to be lowest during sunrise Highest levels are normally by late afternoon Be wary of getting atmospheric oxygen into sample taken from measured dissolved oxygen. Most necessary if sample taken early morning or DO in pond is low from overloading Measure DO with electric meter adn probe if possible and do not allow membrane on end of probe to e exposed to atmosphere during actual DO measurement

Location decision

Same considerations for placement of plants is same for ponds Isolation should be as great as economically reasonable Prevents nuiscances with odors and insects associated with ponds distributing people Directions to prevailing winds will help prevent complains from people downwind of pond Wind is desirable in terms of blowing surface scum and weeds to one side to be removed, and can help mix contents of pond like DO algae and incoming wastes Undesirable aspects of wind is creation of waves that erode pond levee Arrange pond so winds blow across short width of pond rather than length in order to reduce levee erosion

Levees

Selection for steepness of levee slope msut depend on several factors Steep slopes erode faster, from wave wash unless protected against this Steep also minimizes weed growth Equipment operation and routine maintenance are harder on steep slopes Gentle slope erodes least from wavers and easier to work with but more weeds Must have provisions to compact and seal levee banks to prevent leaking Pipes passing through levees should be as close to horizontal as possible to reduce possibility of leaks Cut off walls should be installed when pipes pass through levees prevent leakage Proper compaction and sealing is necessary around pipes Splash pads cleanouts valves inlet and outlet control structures ands also recirculation transfer adn drain lines Top of levee should be atleast 10 feet wide to allow maintenance vehicles and provisions made for rounding or sloping top to allow drainage Pave or gravel levee surface if it will be used as roadway during wet weather

Pond emptying process

Should be slowed as if its too quick, a wet side slope along shoreline may slide into pond, emptied in two weeks or less depending on how much water is beig discharged Normally 1 to 1.5 feet of water are left at bottom of pond

Surface aerators

Should have easy access and sufficient space for maintenance and repair of fixed aerators Alternate anchor points should be installed to. Allow moving of floating aerators Be sure electical cables are long enough to permit easy movement of aerator and large enough to handle anticipated loads

Shutting down pond

Shut down for short periods fo time without any problems developing. If flow to pond stopped to repair a pipe or valve, no precautionary procedures are necessary, if pond is full and received no flows for long periods of time, start up pond with caution and gradually increase the load if full load is applied immediately pond may become overloaded because microorganisms in pond is low and insufficient to treat the load Stop all flow to pond when emptying it and to remove bottom deposits, repair inlet or outlet structures, and when repairing the levees. Drain by use of discharge valves or pump water from one pond to other ponds Try to feed other ponds equally to prevent them from being overloaded, frequently there is time lag from overloading of a pond and the development of problems, watch other ponds and lab results closely for signs like odors low pH low DO drop in alkalinity, loss of green color of potential problems developing

Pond operation

Simple to operate, so neglected more than any other type fo treatment process Complains from ponds come from neglect or poor housekeeping

High pressure air purging cleaning

Some aerated lagoon facilities can apply 90 PSI of compressed air to the system just after the blowers and the air manifold Air manifold valves and blowers should be off when this is done. This is not the pressure level taht will reach lagoon tubing because of friction losses in tubing system, high pressure cleaning will greatly deform the slits in tubing and break off deposits farther back in the tubing, high pressure air can be applied for 3-5 minutes once a year for cleaning

Waste loading on ponds

Spoke in relation to its area may be stated in several different ways - persons or population served per acre (this is population loading) -inches (or feet) of depth added per day (called hydraulic loading or overflow rate) - pounds of BOD per day per acre = lbs BOD/day/acre this is called organic loading

Starting a pond

Start during warmer part of year Shallow starting depth allows contents of pond to cool to rapidly if nights are cold so starting in warmer weather producers more efficient treatment process

Frequency and location of lab samples for ponds

Table 9.3 page 315

Bioflocculation

The clumping together of fine, dispersed organic particles by the action of certain bacteria and algae. Results in faster and more complete settling of organic solids in wastewater

Pond performance by design

The design of pond is determined by waste discharge requirements or water quality standards Overall treatment efficiency may be about same as primary treatment only in settling of solids, or may be equivalent to best secondary biological treatment plants Ponds in hot arid areas have been designed to take advantage of percolation and high evaporation rates so that there is no discharge Ponds can be expected to provide BOd removals of 50-90 percent, facultative ponds under normal design loads with 50-60 day detention times will usually removal about 90-95 percent of coliform bacteria and 70-80 percent of BOD load with 80 percent of time 180 day detention times can produce BOd removals of 85-95 percent total suspended solids removal of 85 to 95 percent and fecal coliform reductions up to 99 percent Physical sedimentation removes 90 percent of suspended solids in three days 80 percent of dissolved suspended solids are removed by biological action in ten days, however in a pond with healthy algal and bacterial population bioflocculation can occur

Molecular oxygen

The oxygen molecule, O2, that is not combined with another element to form a compound.

Bioflocculation

This removes approximately 85 percent of both suspended and dissolved solids within hours Accelerated by increased temperature wave action and highly dissolved oxygen content

Pond treatment efficiency biological factors

Type of bacteria present Type and quantity of algae Activity in organisms Nutrient deficiencies Toxic concentrations

Pond treatment efficiencies physical factors

Type of soil surface area Depth Wind action Sunlight Temperature Short circuiting Inflow variations

Polishing ponds

Used after trickling filter and secondary clarifier in treatment process to provide tertiary treatment to water effluent Goes primary clarifier trickling filter then secondary clarifier pond 1 then pond 2

Ponding of raw water

Used for single families as well as large cities up to size of big cities During dry season most treatment accomplished by broad irrigation and grass filtration While wet seasons most of the 130 million gallon flow was handled by ponds and discharged into receiving waters Modern lagoon system treats all of Melbourne Australia's wastewater

History of ponds

Used in ancient orient and ancient europe discharged wastewater to nearby bodies of water, worked until they were overloaded Waste in ponds fertilized encouraged the growth of algae which increased fish populations and this practice is still continued and recognized art in Germany First ponds in US had purpose of keeping wastewater from flowing tiny objectionable places These ponds performed treatment process that finally became recognized in 1920s By 1950 ponds were used to treat small municipalities and industries and by 1980 7000 waste stabilization lagoons were artificially constructed with one third of all secondary treatment facilities include pond system of one type or another, just over 90 percent are for flows 1 million gallons or less Used by larger cities for water treatment as well,

Removal of tubing and cleaning

Very thorough but time consuming job is drawdown lagoon and annually clean tubing slits. Tubing can be flexed by hand or with special equipment Can avoid draining pond by using a boat and retrieving one line of tubing and manually flexing each section of tubing

Weed and insect control

Weed control apart of good housekeeping and not a formidable task with modern herbicides and soil sterilants Weeds on edge are most objectionable because they allow a sheltered area for mosquito breeding and scum accumulation Weeds also under pond circulation Weeds like tules will grow in depths shallower than 3 feet so operating pond level of at least this depth is necessary tules may emerge singly or be well scattered but must be removed Daily practice of close inspection and immediate removal of young plants is best method fo control

Overturn

When solids start floating to surface of pond during spring or fall an overturn is happening, pond needs to be taken out of service and cleaned, measurement of sludge depth on bottom of pond will inidcate when pond should be cleaned, usually ponds cleaned when wet sludge is over one foot deep

Mosquitos

Will breed in sheltered areas of standing water where vegetation or scum to which egg rafts of the female mosquito can become attracted. Egg rafts are fragile and will not withstand action of disturbed water surface caused by wind action or normal currents, keep water edge clear of vegetation and keep scum broken up will give adequate control. Shallow isolated pools left by receding pond level should be drained or sprayed with larvicide Stocking density of 2500 fish per acre with species of mosquito fish can help control population. Stocking levels depend on local situation and environmental conditions.

Anaerobic ponds

Without dissolved oxygen through entire depth Treatment depends on fermentation of sludge at pond bottom, this process is quite odorous under certain condition by highly efficient at treating organic wastes, mainly used for processing industrial waste although some domestic waste ponds become anaerobic when badly overloaded

Land treatment

You can improve effluent quality by applying pond effluent to an overland flow system constructed by wetland water treatment system Overflow system consists of grass planted slowly over permeable soil and slopes from 0-8 percent slope lengths range from 100-200 feet the application rate is expressed in inches per day and depends on treatment requirements and local conditions Application periods usually range from 6-12 hours a day BOD removals are 75-90 percent range

Distribute inflow equally into ponds

all ponds designed to receive flow should receive same hydraulic or organic loadings

Operating strategy

develop a plan - maintain constant water elevations in the ponds if NPDES permit allows constant discharge of pond to receiving waters.

PH

expression of hydrogen ion concentration and resulting acidity of a substance determines intensity of basic or acidic condition, is logarithm measurement of hydrogen ion presence,

Types of tests purpose

pH DO and temperature are indicators of the pond BOD coliform and solids test measure the efficiency of the pond in treating wastes BOD is used to calculate the loading on the pond

Photosynthesis

process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches. Uses chlorophyll green plant enzyme

Median

the middle score in a distribution; half the scores are above it and half are below it Several measurements ranked by value, half of measurements are larger and half are smaller

Percolation

the slow passage of a liquid through a filtering medium or gradual penetration of soil and rocks by water