quiz 8: ch 29

although the dissolved O2 content of natural waters is generally 5 to 10 mg/liter, the biochemical oxygen demand (BOD) of raw sewage is typically between _______ mg/liter, meaning the addition of raw sewage to a lake could easily deplete the dissolved O2 in that water

300 to 400

Presence/absence test

A 100 mL water sample is added to a lactose-containing broth that is selective for Gram-negative rods. An inverted tube is included to trap gas. If gas is produced, the broth is then tested to confirm that coliforms are present.

Sanitary Landfill

A site used for disposal of non-hazardous solid wastes in a manner that minimizes damage to human health and the environment.

Rural homes usually rely on septic systems

A small-scale on-site wastewater treatment system in which the sludge settles out and is degraded by microorganisms while the effluent percolates through a drain field.

Secondary Treatment

A wastewater treatment process that uses microbes to convert suspended solids to inorganic compounds and removable cell mass.

Primary Treatment

A wastewater treatment process used to remove material that settles out.

ONPG/MUG test

A water sample is added to a medium containing ONPG (o-nitrophenyl-β-D-galactopyranoside) and MUG (4-methyl-umbelliferyl-β-D-glucuronide). Lactose-fermenting bacteria hydrolyze ONPG, generating a yellow compound; thus, all coliforms turn the medium yellow (figure 29.7). E. coli produces an enzyme that hydrolyzes MUG, making a fluorescent compound. Because of ONPG and MUG, a sample can be tested simultaneously for both total coliforms and E. coli.

Membrane filtration

A water sample is passed through a filter that retains bacteria (see figure 4.20), collecting them from a known volume of water. The filter is then placed on a lactose-containing selective and differential agar medium.

Methods used for secondary treatment include:

Activated sludge process Trickling filter (TF) system Lagoons Constructed wetlands

Disinfection of Effluent

Before discharge into the receiving water, the effluent is disinfected with chlorine, ozone, or UV light to decrease the numbers of microorganisms and viruses.

before discharge, the effluent is typically disinfected using ____

UV light, chlorine, ozone

a sample of wastewater is incubated in a sealed container in the dark under standard conditions of time and temperature, usually 5 days at 20 degrees C. During that time, microbes in the sample will degrade the organic material. The level of oxygen before and after this incubation reflects the ______

biochemical oxygen demand

the trickling filter has a rotating arm that spray effluent over a bed of plastic pieces or course gravel and rocks that are coated with ______

biofilm

secondary wastewater treatment is chiefly a ______ process that converts most of the suspended solids to inorganic compounds

biological

in addition to cleaning up wastewater, we also must dispose of solid waste, another name for _____

garbage

Methods used to detect total coliforms in a water sample include:

-ONPG/MUG test -Presence/absence test -Most probable number (MPN) method -Membrane filtration

advanced treatment

-This includes any purification process beyond secondary treatment; it may involve physical, chemical, or biological processes, or any combination of these. Advanced treatment is expensive, however, and has not been common in the past. -Advanced treatment is often designed to remove ammonia, nitrates, and phosphates—compounds that foster growth of algae and cyanobacteria in receiving waters.

the process of composting can be facilitated by _____

-adding soil and water -stirring and turning pile frequently

Sanitary landfills

-are widely used to dispose of non-hazardous solid wastes in a manner that minimizes damage to human health and the environment.

In what ways can bacteria be used during advancement treatment to remove nitrate from wastewater

-dentrifying bacteria which use nitrate as a terminal electron acceptor during anaerobic respiration -anammox bacteria which use ammonia as an energy source and nitrate as a terminal electron acceptor

regulations now govern the maximum level of contaminants in drinking water, including _______

-enteric viruses -giardia cysts -cryptosporidium oocytes

factors that will increase the degradation of pollutants

-increase the growth rate of microorganisms -providing optimal moisture -maintaining the ph near neutral -providing adequate nutrients

microorganisms are important in the treatment of water, wastes, and polluted habitats because

-some are pathogens and must be removed from sewage before discharge and drinking water before it is safe for human consumption -they are the ultimate recyclers, playing an essential role in the decomposition of our wastes

as part of the safe drinking water act, the revised total coliform rule (RTCR) outlines _____

-the sample collection requirements for water testing -monitoring and corrective actions if samples are positive for total coliform or E. coli

every day the average American _____

-uses up to 100 gallons of water -generates about 80 gallons of waste water -produces 5 pounds of trash

Steps involved in primary treatment of wastewater

1) raw sewage is passed through a series of screens 2) skimmers remove skum and floating material 3) sewage sits in a sedimentation tank 4) sludge is removed and effluent is sent to a secondary treatment

Water Treatment Processes

1) settling: large materials settled out 2) coagulation: alum or other added chemicals combine with suspended material to form clumps 3) sedimentation: the coagulated materials settle to the bottom 4) filtration: sand and grave filters remove microorganisms including protozoan cysts and oocytes. Activated charcoal filters remove dissolved chemicals 5) disinfection and storage: chlorine, ozone, or other chemical disinfectants are added. UV irradiation may also be used to destroy microbes

water treatment process

1) water flows in a water holding tank and stands long enough for particulate matter to settle 2) water is transferred to a tank and mixed with a coagulant 3) mixture is sent to a sedimentation tank, where coagulated materials sink to bottom 4) coagulated material is removed and remaining water is filtered to remove bacteria and oocytes and cysts 5) additional filtration though activated charcoal removes harmful chemicals 6) water is treated with chlorine or other disinfectants to kill or inactivate harmful microbes

Septic System

An individual wastewater treatment system in which the sludge settles out and is degraded by microorganisms while the effluent percolates through a drain field.

An important goal of wastewater treatment is to decrease the environmental impact by reducing the biochemical oxygen demand (BOD)

High BOD values indicate that large amounts of degradable materials are present, resulting in the consumption of correspondingly large amounts of O2 during biological degradation of the material. The BOD of raw sewage is approximately 300 to 400 mg/liter, whereas the dissolved O2 content of natural waters is generally 5 to 10 mg/liter. Thus, adding raw sewage to a lake could easily deplete the dissolved O2 in that water.

Advanced Treatment

In wastewater treatment, any physical, chemical, or biological purification process beyond secondary treatment.

Wastewater

Material that flows from household plumbing systems; municipal wastewater also includes business and industrial wastes and stormwater runoff.

Compost

Material that results from the controlled decomposition of solid organic material.

Indicator Organisms

Microbes whose presence in an environment suggests fecal contamination.

anaerobic digestion

Process that uses anaerobic microbes to degrade the sludge obtained during wastewater treatment. -Organic compounds → organic acids, CO2, H2 -Organic acids → acetate, CO2, H2 -Acetate, CO2, H2 → methane (CH4) -After anaerobic digestion, water is removed from the remaining sludge, generating a nutrient-rich product called stabilized sludge. This can be incinerated or disposed of in landfills, but biosolids—a term for stabilized sludge that meets certain standards—may be used to improve soils and promote plant growth. An increasing number of wastewater treatment facilities are finding ways to recycle their treated sludge. Concerns exist, however, about heavy metals and other pollutants that can sometimes be concentrated in the product.

Bioremediation

Process that uses microorganisms to degrade harmful chemicals.

Biochemical Oxygen Demand (BOD)

The amount of O2 required for the microbial decomposition of organic matter in a sample.

Sludge

The solid portion of wastewater that settles to the bottom of sedimentation tanks during primary and secondary treatment.

Lagoons

The wastewater is channeled into shallow ponds, or lagoons, where it remains for several days to a month or more, depending on the design of the lagoon. Algae and cyanobacteria that grow at the surface provide O2, allowing aerobic organisms in the ponds to degrade the organic materials.

Constructed wetlands

These follow the same principles as lagoons, but their more advanced designs make them suitable habitats for birds and other wildlife (figure 29.3). For example, the wastewater treatment processes in Arcata, California, use a series of marshes that now attract a variety of shorebirds and serve as a wildlife sanctuary.

Activated sludge process

This common system relies on mixed populations of aerobic microbes that grow as flocs (suspended biofilms). Although the organisms are often naturally present in wastewater, large numbers are added by introducing a small portion of leftover sludge from the previous load of treated wastes. Plenty of O2 is supplied by mixing the wastewater in an aerator. As the microbes multiply, the organic matter is converted into both biomass and waste products such as CO2. Following the aeration, the wastewater is again sent to a sedimentation tank. There, most of the flocs settle and the resulting secondary sludge is removed and pumped to the anaerobic sludge digester. A portion of this sludge is introduced to a new load of wastewater to act as an inoculum.

Trickling filter (TF) system

This method is frequently used in smaller wastewater treatment plants. The TF has a rotating arm that distributes the liquid waste over a bed of plastic pieces or coarse gravel and rocks (figure 29.2). The surfaces of these materials become coated with a biofilm—a mix of bacteria, fungi, algae, protozoa, and nematodes—that aerobically degrades the organic material as it passes. The rate of wastewater flow can be adjusted for maximum degradation.

Most probable number (MPN) method

This statistical assay of cell numbers uses successive dilutions to determine the most probable number of bacteria in a sample (see figure 4.21). To test drinking water, the broth used is similar to that in the presence/absence test, and each tube includes a small inverted tube to trap gas. MPN tubes that show gas production are further tested to confirm that they contain coliforms.

to minimize the risk of chlorine that cone pose some heath concerns what else can be used?

Ultraviolet light and ozone

the activated sludge process is an ____ method

aerobic

in a lagoon an ______ of organisms degrade the organic matter

aerobic mixture

the high nutrient content of wastewater can be damaging to rivers and lakes because it supports

aerobic respiration that depletes dissolved O2, leading to death of fish and other aquatic animals

removing nitrates, phosphates, and ammonia from wastewater helps to eliminate the overgrowth of ______ in receiving waters

algae and cyanobacteria

sludge obtained during the sedimentation steps of primary and secondary treatment is transferred to a tank for _______

anaerobic digestion

the DDT gets into water, it concentrates in minute plankton, which are eaten my minnows, which are eaten by fish, which are eaten by predator birds, until the final concentration of DDT in the birds is increased at a level that causes fragile egg syndrome. This process is _______

biological magnification

_______ is the use of microorganisms to degrade or detoxify pollutants in a given environment

bioremediation

_______ enhances growth of local microbes in a contaminated site by providing additional nutrients

biostimulation

There are two general bioremediation strategies

biostimulation and bioaugmentation

_______ is the natural decomposition of organic solid material and offers an alternative to landfills

composting

________ mostly resemble lagoons in design and function but offer more in the way of habitats for birds and other wildlife

constructed wetlands

the main difference between the presence/absence test and the MPN test for detecting coliforms is _______

dictions of the water sample are made in the MPN test

Municipal Wastewater Treatment Methods

effluent: The liquid portion of treated wastewater. sludge: solid portion

Biostimulation

enhances growth of resident microbes in a contaminated site by providing additional nutrients.

public water systems are regulated by

environmental protection agency (EPA) and Safe water drinking act

because some coliforms can thrive in soils and on plant material, their presence does not necessarily imply fecal pollution. To compensate for this shortcoming, a subset of coliforms, or ______ coliforms, are also used as indicator organisms

fecal

the most common groups of bacteria used as indicator organisms in the U.S. are _____

fecal coliforms and total coliforms

in the context of drinking water, finding indicator organisms suggests ______

fecal contamination

Primary treatment

is a physical process designed to remove large objects and material that will settle out.

Secondary treatment

is mainly a biological process that converts most of the suspended solids to inorganic compounds and cell mass that can then be removed, eliminating as much as 95% of the BOD. Microbial growth is actively encouraged during secondary treatment, allowing aerobic organisms to oxidize the biologically degradable organic material to CO2 and H2O. Because secondary treatment relies on the metabolic activities of microorganisms, the processes could be devastated if too much toxic industrial waste or too many hazardous household materials were dumped into wastewater systems, killing the microbial population.

Bioremediation

is the use of microorganisms to degrade or detoxify pollutants in a given environment. It generally takes advantage of organisms already present, but in some cases specific organisms are added to the polluted environment.

The most common bacterial group used as indicator organisms in the United States is total coliforms

lactose-fermenting members of the family Enterobacteriaceae, including Escherichia coli. -most reside in the intestine so they are a sign of fecal contamination -Facultative, non-spore-forming, Gram-negative rods that ferment lactose, producing acid and gas within 48 hours at 35°C; most reside in the intestine, so they are used as indicators of fecal pollution; also simply called coliforms.

_____ gas, resulting from the anaerobic decomposition of organic matter in sanitary landfills, is vented and then burned or recovered for use

methane

synthetic compounds are _____ likely to be biodegradable if their chemical composition is similar to that of naturally occurring substances

more

septic systems _______

must be properly designed and monitored to ensure they work adequately

Wastewater

or sewage, is composed of all the material that flows from household plumbing systems, including toilet wastes as well as washing and bathing water. Municipal wastewater also includes business and industrial wastes. In many cities, stormwater runoff that flows into street drains enters the system as well.

wastewater must be treated with discharge to remove ______ that may cause diarrheal diseases and hepatitis

pathogenic microbes

if composting is done correctly, the inside of the pile heats up due to the metabolic reactions of multiplying microbes. Achieving temperatures of 55 degrees C to 66 degrees C Is Important to kill ______ although thermophilic organisms will continue decomposing the material

pathogens

in the United States, the Clean Water Act mandates _______ treatment by large-scale wastewater treatment plants

primary and secondary

Large-scale wastewater treatment plants in the United States use a series of two processes

primary and secondary treatment

what promote pollutant degradation?

providing adequate nutrients, maintaining a nearly neutral pH, raising the temperature, and providing an optimal amount of moisture

Bioaugmentation

relies on activities of microorganisms added to the contaminated material, complementing the resident population. -The activated sludge process used during secondary treatment of wastewater is a form of bioaugmentation.

rural homes traditionally rely upon _____ for wastewater treatment

septic systems

what would least likely contain pathogens

tap water

To determine the BOD of a sample

the O2 level is first measured. The sample is then incubated in a sealed container in the dark under standard conditions of time and temperature, usually 5 days at 20°C. During that time, microbes in the sample will degrade the organic material. The O2 level is then determined again. The difference between the amount of dissolved O2 at the beginning of the test and the amount at the end reflects the BOD. In the case of samples that have a very high BOD, they must be diluted first. Otherwise, the O2 in the water could be depleted before the sample has been completely decomposed.

biochemical oxygen demand (BOD)

the amount of O2 required for the microbial decomposition of organic matter in a given sample.

Composting is the process of making compost

the material that results from the controlled decomposition of solid organic material.

indicator organsims

these microbes are routinely found in feces, survive longer than intestinal pathogens, and are relatively easy to detect. Finding them suggests fecal contamination, and therefore a greater chance that intestinal pathogens are also present.--> water testing

how do membrane filters function to trap bacteria

they contain pores so small that bacteria cannot pass through

all the material that flows from household plumbing, including toilet wastes as well as washing and bathing water, is termed

wastewater