Chapter 20: CE 477 Solid Waste Management

Paper Recycling

1. *about 30-40% of MSW is paper* and about 15% (approximately half) is newspaper 2. the market value of waste paper varies considerably. *it can range from $5 to $80 per ton*. In the late 1980's, there was an increased public interest in in recycling, which created a "glut" (his word, not mine) that drove the prices down a lot. This meant that communities paid as much as $30 per ton to hire someone to take their "recycled" paper to landfills. 3. Separate collection is marginally profitable, but there is uncertainty to future prices, which makes officials reluctant to implement recycling and paper companies reluctant to make major investments. 4. Between 1990 and 1995, the US paper industry planned a multi-billion dollar investment to increase it's recycling capacity. If Randtke left the 1900's, I would tell you if this worked or not. 5. The quality of recycled paper is generally inferior to virgin paper, and the cost may also be higher. *Weirdly, increased use of paper products would help create a better market for recycled paper, but decreased use of paper would result in greater benefit to the environment.* 6. "Environmentalists" often promote paper recycling as a means of "saving trees", but this is misleading. Some products made from recycled paper, such as insulation and soil conditioners, would not be made from trees in the absence of recycled paper. Many of the trees used to make virgin paper are grown for that purpose. *The number of trees in the US has been significantly increasing for the past 25 years, despite the large number used to make paper. 7. Paper recycling can have environmental benefits, but is should not be viewed as an end goal. *The goal should be to maximize the use of resources and minimize costs.* Some virgin material must be used, since the paper fibers become shorter each time each time they are recycled and eventually become too short to use.

Alcohol Production

1. Acid hydrolysis converts cellulose (from paper, yard wastes) to glucose, which yields alcohol upon fermentation. However, one must first separate out the cellulosic materials, slurry them, add acid, then heat the mixture and ferment it. 2. The cost of alcohol from MSW is greater than cost of gasoline, so there is little incentive to produce it. 3. The process produces a waste slurry, which needs to be dewatered and then disposed of.

Tires

1. Between 200 and 250 million passenger-car tires are discarded each year. 2. Tires cause a problem in landfills. No matter how deep they are buried, they tend to float to the surface, which produces a breeding area for mosquitoes. 3. Some governments banned tires from landfills. This means that there is nowhere to dispose of them. 4. In areas where tires are banned from landfills, the disposal method of choice has often been to place them in "temporary" tire piles for storage. This creates two serious problems: 1) the tires are "hot-tub condos" for mosquitoes, generating about 4,000 times as many mosquitoes as an equal area of natural habitat; and 2) they pose a huge fire hazard. 5. In 1988, the largest tire stockpile in the US, containing *35 million tires* was located in CA. A tire-to-energy plant was to be built to deplete tires at the rate of 4 million per year. Tire-to-energy plants is a much more rational approach to tire disposal than landfills or banning tires. 6. Other potential uses for used tires include fuel for cement kilns and electric utilities, retreaded tires, crumb rubber for asphalt, roadbed material, carpet backing, dock bumpers, and construction of offshore artificial reefs.

Six Steps in the Recycling Process

1. Collection 2. Storage 3. Transport 4. Processing 5. Marketing 6. Utilization The public focuses on the first step (collection) and consider it to be synonymous with recycling. Because of this, the true costs of recycling are often ignored, and the benefits are often greatly exaggerated.

Metals and Glass

1. Ferrous metals are recoverable by magnetic separators, and this is economically feasible when the waste is shredded for another reason. Large ferrous waste products (cars, appliances) are readily recycled via scrap metal dealers, steel mills, and foundries. 2. Aluminum is difficult to recover mechanically, but has a high value. *Most recycled aluminum is recovered through collection centers and not separated by mechanical means*. 3. Recovery of glass from mixed wastes produces mixed-color cullet, which can be used in making foamed glass insulation, bricks, or paving materials, *but the market is poor and uncertain*.

Landfill Moisture

A landfill is a biological waste treatment system, and it is primarily anaerobic during much of its active life. Landfills can be economically utilized to recover energy in the form of methane gas. Landfills require moisture to function properly. If a landfill is designed "too well", it can become too dry to support a healthy population of microbes. If MSW is too valuable to be discarded, as some believe, then a landfill could be viewed as a warehouse or mine, where biodegradable components are converted to methane gas (energy), and non-biodegradable components are awaiting the development of an economical means of recovering them.

Composition of MSW Continued

All forms of plastics account for 12 wt% of MSW Approximately 0.25% is contributed by fast-food wrappers Less that 0.25% is Styrofoam (despite negative publicity) Composition determines the potential for recovery of materials or energy Composition varies seasonally and geographically (ex. more grass clippings in warm months, in Santiago, Chile, the MSW was 80% bones at one point). It can also vary over time

Composition of MSW

Basically, table 11-2 in the book breaks down what classifies as what based on composition. *Trash* = highly combustible waste, paper, wood, cardboard (up to 10% treated paper), plastic or rubber scraps, *commercial and industrial sources* *Rubbish* = combustible waste, paper, cartons, rages, wood scraps, combustible floor sweepings, *domestic, commercial and industrial sources* *Refuse* = 50% rubbish and 50% garbage, *residential sources* *Garbage* = animal and vegetable wastes, *institutional, commercial, and club sources* *Animal solids and organic wastes* (ew) = carcasses, organs, solid or organic wastes, *hospital, laboratory, animal pounds, and similar sources* *Gaseous, liquid, or semi-liquid wastes* = industrial process waste *Semi-solid and solid wastes* = combustibles, requiring hearth or grate burning equipment

Pyrolysis

Burning of MSW without oxygen produces combustible gas, tar, and charcoal, which are supposedly usable as chemical feed stocks, but the materials are dirty (unrefined) and generally unmarketable. *This is very rarely used and is considered by experts to offer little hope for the future*

Collection and Transport of MSW

MSW must be picked up and hauled to the disposal site (whether by public or private haulers). In the 70s and 80s, this was 80% of the total disposal cost. The costs have been increasing (although, since his stuff is 20 years out of date, I don't know if it still is) Factors influencing collection cost include: collection equipment purchase, maintenance, and replacement; collection efficiency (point of collection, manpower per collecting unit, routing, collecting time vs. transport time, working conditions, and pay), and frequency of collection. City engineers and administrators should work to minimize collection costs while providing adequate service to minimize odor protection and unsanitary conditions.

Central Separation

involves mechanical separation of MSW at a central processing plant, generally employing shredders, air classifiers, and magnetic separators. Equipment is expensive and troublesome. Typical products are metals (usually only ferrous), mixed glass, and refuse derived fuel

Hazardous Waste

solid wastes that are legally defined to be hazardous

Landfill Cost

"Tipping Fees" are the charges levied by the owners of the landfill. They artificially created a shortage of landfills, causing prices to raise rapidly. The cost of landfill disposal is strongly influenced by the distance to the landfill.

Definition of Solid Waste

"any garbage, refuse, sludge from a waste treatment plant, water supply treatment plant, or air pollution control facility, and other discarded material, including solid, liquid, semisolid, or contained gaseous material resulting from industrial, commercial, mining, and agricultural operations, and from community activities, but does not include solid or dissolved material in domestic sewage" basically solid waste is a synonym for refuse. this can kinda include anything, so it depends on how you want to define it. You can define solid waste using point of origin (domestic, commercial, etc), nature of the material (organic, combustible, etc), and heat content of the waste

The KU Styrofoam Ban

1. In 1989, Styrofoam came under attack at KU. The UDK and some student groups petitioned to ban Styrofoam based on "environmental concern", emotion, coercion, and rhetoric, rather than a thorough, scientific, and rational evaluation of alternatives. 2. Styrofoam is relatively non-degradable. The only biodegradable alternative is paper cups, but 1) paper cups are manufactured from trees, which remove CO2 from the air, 2) toxic chemicals are used to manufacture them, 3) paper manufacture produces large amounts of toxic wastewater, 4) biodegration of paper products in landfills contribures to leachate production, 5) more energy and fossil fuels are used to make paper cups than Styrofoam 3. Blah Blah Blah. There's a lot of info about why a ban on Styrofoam wasn't the best solution. *the gist of this section was that you should look at a problem as a whole, rather than picking a fight. It's kinda like the banning straws thing. It doesn't help as a whole and there are bigger problems to focus on.*

Disposal Options for MSW

1. Incineration 2. Sanitary Landfills 3. Composting 4. Ocean Dumping

Methane Production

1. MSW can be slurried and then digested anaerobically to produce methane gas. This requires separation of the degradable materials, a large capital investment, and handling and disposal of the residual sludge. Also, the gas might have to be purified before use. 2. Gas recovery from landfills is rapidly increasing. Landfill gas not only represents a threat to nearby property owners, but it also contributes to global warming. Landfill gas can be recovered by sinking ventilation shafts into the landfill and the gas can be flared, burned to generate electricity, or upgraded to pipeline grade natural gas. 3. Codisposal, anaerobic digestion of a mixture of MSW and sewage sludge to produce methane, is also being tired in some locations.

Plastics

1. Plastics are relatively non-biodegradable, so they do not generate much leachate and are otherwise non-polluting when properly managed. *The major problem with plastics is littering.* 2. Plastics account for about 12% of MSW by weight, but account for a much larger percentage by volume (think of a gallon milk container). 3. Plastics are combustible and can be burned as fuel along with other MSW components. Some plastics, such as PVC, contain chlorine, which may be converted into hydrochloric acid or chlorinated organic compounds. These can be removed by scrubbing. 4. There are many types of plastics. Most are not compatible with other plastics when recycled and some can not be reformed into the same product again. Individual plastics have historically comprised only a tiny fraction of MSW, making recycling infeasible. 5. There is lots of research on new plastics and ways to recycle them. 6. There are "degradable" plastics, which break down when exposed to sunlight. These materials are not readily degradable in landfills, and they may be incompatible with recyclable plastics, which interferes with recycling efforts. Degradable plastics are also weaker than non-degradable plastics, so extra plastic must be used to create a product of similar strength. This means that more non-renewable resources are being used.

The Scrap Processing Industry

1. The Institute of Scrap Recycling Industries (ISRA) has more than 1800 members who process, broker, and consume materials that are not considered part of the municipal waste stream. In 1988, they recycled 80 million pounds of material. 2. Scrap dealers provide a lot of the US's aluminum, iron, steel, lead, etc.

Steam Generating Incinerators

1. The technology dates back to the 1890s. It can be designed to produce steam heat or electricity. 2. Their use has increased due to resistance to landfill construction. 3. They require a good supply of MSW, compliance with air pollution control regulations, landfilling of waste ash, a large capital investment, etc. There is also strong opposition to the siting of these facilities by neighbors concerned about "toxic emissions" 4. *Cogeneration: coal or oil is supplemented with MSW or RDF (refuse-dereived-fuel) or dried sewage sludge* 5. Recycling of yard waste, paper, plastics, and other combustible materials reduces the fuel value of MSW and thereby interferes with waste-to-energy projects.

State and Local Regulations

1. anxious to make "progress", many state and local governments have developed new regulatory approaches to their MSW problems 2. Many cities have adopted recycling goals, but some, including NYC, have made the goals mandatory. 3. In 1986, Rhode Island became the first state to legislate mandatory recycling. The state opened a $5M recycling facility designed to process 168 tons/day of newspaper and 210 tons/day of mixed recyclables.

Recycling of Beverage Containers (why is there a whole section on this??)

1. decades ago, almost 100% of glass bottles were recycled. They were quite heavy and the transportation costs were high. The aluminum can developed as an energy saving alternative and was marketed to the public as a much more convenient container precisely because it was non-returnable 2. Due to the high value of aluminum, recycling centers began to purchase used aluminum cans (yay). An increase in energy prices in the 70s increased the value of aluminum, prompting more recycling 3. The recycling of non-returnable containers has been encouraged by the beverage industry. The energy savings obtained by recycling non-refillable containers are not much different than those obtained by using refillable containers. 4. Recycling saves about 95% of the energy required to make a new can (yay!). 5. *aluminum is the single most valuable component of MSW*. Proponents of mandatory recycling generally exaggerate its worth. 6. ferrous metal cans are easily recovered by magnetic separation

Obstacles to Recycling

1. lack of cooperation by the public 2. resource recovery requires both a market for the recovered material and a means of recovering the material economically 3. MSW is a non-uniform material and therefore requires a separation for recovery of the resources within it 4. the material in MSW is worth only about $5/ton *after* separation and MSW typically costs only about $15-20/ton to dispose of in a landfill, so there is little opportunity for economical recovery of resources 5. the technology for recovering materials from MSW (in the absence of source separation) is generally quite expensive and often unreliable 6. the market for many of the products that might be recovered from MSW is unreliable (lack of long term markets, fluctuations in demand, uncertainty of supply) 7. the public and their representatives often fail to recognize the potential benefits of resource recovery or the opportunities that are available for economical recovery of resources

Landfill Design

Daily cells 6-8' thick covered with 6" of dirt, a 2' cover (sloped for good drainage). Most commonly used liner is clay, but bitumen or plastic may be used. Some factors to consider: soil permeability, drainage, wind direction, hauling distance, size, potential use after landfill is full, and the "not in my back yard" (NIMBY) problem Leachate, the liquid that drains from the bottom of the landfill is highly polluted and contains large amounts of BOD, COD, NH3, TDS, and metals

1970 Resource Recovery Act

Funded planning, research, and demonstration grants to promote recovery of resources from solid wastes

Management Options for MSW

Per Professor Rathje: "dump it, burn it, convert it, minimize it" Per Mr. Bill Franklin: "reuse, recycle, compost, burn, landfill" The "three Rs": reduce, reuse, recycle

Recovery of Materials from MSW (ex. recycling)

Recycling is centuries old. It is much easier to recycle in densely populated areas due to economies of scale and transportation costs. (Ex. easier and more cost-effective to recycle the New York Times than some rural town) Recycling is often driven by economic factors. The best recycling efforts have been during times of economic distress (the Great Depression, WWII). Recycling has been increasing recently, since the standard of living has been falling, and the public is deeply concerned about the environment. Policy makers are beginning to include the costs of environmental damages in decisions about recycling efforts.

Catch-22 of Recycling

Recycling will not be economical without a good market for the material, but a stable market will not develop without a steady flow of recyclable material. Some have attempted to solve the problem by mandating recycling in the hope that markets will develop, but such action can destabilize an already weak market. In some cases, when markets for recycled materials become saturated, the materials collected for recycling have had to be hauled off (*at a cost*) to a landfill.

Primary Goal of Recycling

The primary goal is to minimize the total cost to society (including environmental costs). Recycling has achieved a status similar to that of "motherhood and apple pie", meaning that it has become the goal, rather than a means to an end. Basically, the goal shouldn't be to recycle if the costs exceed the benefits or if net damage to the environment results from failure to include the environmental costs associated with transport, processing, and marketing. Many recycling efforts are heavily subsidized by government grants, volunteer labor (at the recycling center or by the public), benefit concerts, etc. If such subsidies are not properly accounted for in examining the economics of a recycling project, erroneous conclusions may be drawn regarding the true costs and benefits of recycling.

Quantity of MSW (the MSW "crisis")

The problem of MSW is growing, but only because the population is growing. Per capita waste production has not increased significantly during this century (meaning the 1900's cause Randtke is old...his data is from 1903 to 1988) Lots of the reasons that this appears to be a crisis is that the number of disposal facilities dropped abruptly. Recycling is proposed as a solution, but only 20-50% of MSW has potential to be recycled, and the rest still needs to be disposed of.

Products and Product Packaging

There is increasing public and legislate pressure on manufacturers to make products and packaging out of recycled materials and to create designs that are more readily recyclable. Terms associated with such efforts include: "green design", "take-back programs" and "extended producer responsibility"

1965 Solid Waste Disposal Act

This act was directed primarily at municipal solid waste problems, especially open burning in dumps that was creating air pollution. The act authorized a survey of the problem, grants, and funds for research.

1976 Resource Conservation and Recovery Act (RCRA)

This was a comprehensive piece of legislation addressing solid and hazardous waste problems; the act (*amended in 1984*) governs management of MSW as well as hazardous waste that is currently being generated. Provided technical and financial assistance to develop plans and facilities for the recovery of energy and other resources from discarded materials. Authorized EPA to set guidelines for the design, operation, and performance of sanitary landfills, addressing such problems as location of landfills in floodplains, destruction of the habitat of endangered species, contamination of surface and ground water by leachate and site runoff, degradation of air quality, and threats to the health and safety of workers and nearby citizens.

1990 Clean Air Act

Under the authority of this act, the US EPA, in September 1991, proposed new standards and guidelines for landfills. 620 existing and 90 proposed landfills handling at least 100,000 metric tons per year were to be required to install gas collection systems. The cost of compliance with the rule was estimated to be about $240 million.

Landfill Space

We aren't running out of landfill space. It is just a NIMBY problem. Old landfill space normally is turned into parks or golf courses.

Composting

an aerobic digestion process. Only the biodegradable components of MSW (newspaper, food waste, etc) undergo a significant transformation during composting. Composting yard wastes can reduce MSW disposal costs, and many communities (like Lawrence) required composting of yard waste to extend the life of landfills

Garbage (definition from book, not packet)

animal and vegetable waste resulting from the handling, preparation, cooking, and serving of food

Sanitary Landfills

covered landfills prevented fires, rodents, insects, odors, and disease common with open dumps. Today, sanitary landfills are the best way to dispose of solid waste

Energy Recovery from MSW

energy recovery from MSW can help reduce dependence on fossil fuels and other sources of energy. 100% recovery of fuel value of MSW would supply only 3 to 5% of the nation's energy demand. *energy recovery is an attractive option because it kills two stoned birds by reducing waste and producing energy* This is not usually considered a form of recycling

MSW

municipal solid waste

Incineration

reduces volume by 70-90%, increased energy costs caused many incinerators to be abandoned, steam generating incinerators are increasing

Source Separation

separation by the waste generators (ex. individual households). *This is the cheapest option.* Aluminum, paper, and glass are the most commonly separated items. Cooperation is the biggest problem. Curbside recycling is generally the most effective way to encourage source separation. From 1988 to 1995 (which Randtke thinks is still relevant....) recycling grew. He will probably say it still is, since he doesn't bother to update his material. Curbside recycling is very labor and energy intensive (people have to drive around and pick them up). It also doesn't guarantee net environmental benefits.

Ocean Dumping

used in the past by costal cities, especially in Eastern U.S., but caused extensive pollution ocean dumping of MSW was banned by federal law in 1977