international: Bio-waste: A Disposal Problem or a Resource?

What's a community to do when landfilling bio-waste isn't an option?

Germany's Recycling and Waste Act of October 7, 1996 already requires its citizens to recycle as much of its waste as possible. Incineration and energy recovery are other disposal options. However, the country's new Technical Directive for Built-Up Area Waste means that landfills will have stricter requirements and are likely to accept only non-reactive incineration residues beginning in 2005.

Under this new directive, technical treatment of bio-waste leads to either reusable (usually saleable) products or to incineration. Whether separate bio-organic and inorganic residential collection can be justified is questionable if all the materials end up in the same incinerator.

Consequently, the more logical solution in fitting with the German Recycling Act is to return bio-organic waste to the natural cycle. However, this has to be done without affecting the existing regulations and also must be cost-efficient.

Germany generates approximately 12 million tonnes of bio-waste from households and businesses annually. In addition, large quantities of bio-residues from farms and from the food and beverage industries are generated. Sugar beet processing alone generates more than 20 million tonnes of waste a year, and livestock farming floods the nation with 190 million tonnes of liquid manure (containing 13.5 million tonnes of solids).

To top things off, approximately 3.5 million tonnes p.a. of sewage sludge solids are produced annually by sewage treatment plants.

Between 1993 and 1997, the number of composting facilities had risen from 133 to about 400, which results in approximately 4 million tonnes of bio-waste, garden and park waste being converted into 2 million tonnes of compost.

Composting this large amount is expensive both in production and in monitoring it to maintain a consistent quality level that eliminates pollutants. Composts that cannot be sold or that are of insufficient quality must be disposed of, or, in the future, must be incinerated, which is expensive due to the "double treatment" involved. Many facilities already are experiencing problems in selling their compost because the supply is increasing faster than the demand.

While the potential income from the end-product is falling, composting facilities are becoming more elaborate and expensive, due to increasingly stringent environmental legislation.

Farmers are the largest potential customers for bio-waste fertilizers. However, a substantial proportion of the 3.5 million tonnes of sewage sludge is waiting to be recycled on Germany's farmlands, too. The landfill prohibition of the Technical Directive for Built-Up Area Waste has pulled the rug out from under the arrangements for sewage sludge disposal, and farmers want to receive money for accepting sewage sludge rather than pay for it. Thus, it is nearly impossible to sell compost to this market.

Anaerobic treatment is another solution, whereby:

* biogas is produced, which can be recycled for energy;

* the substances are broken down more thoroughly than by aerobic composting, an advantage when the residues are destined for thermal disposal; and

* the fermentation process is less emission-intensive than aerobic composting.

If all of Germany's bio-organic wastes were aerobically treated, they would produce a biogas potential of 6.9 billion cubic meters per year, or nearly 7 percent of Germany's current natural gas consumption.

While up to 50 percent of the original substances are broken down during composting, fermentation can further reduce the proportion to one third of the original mass. In addition, decomposition takes place inside an enclosed fermenter, and odor-intensive steps, such as acid fermentation as part of aerobic decomposition, are not required.

In the fermentation process' liquid environment, germ-laden dusts are not produced. And if fermentation residues don't need to be composted, then anaerobic facilities will require less ground space than composting plants.

How and where the market for bio-waste treatment techniques will move in Germany's future depends less on technical innovations than on how the statutory framework conditions evolve. However, recent legislation has created more uncertainty, rather than creating stable, calculable conditions for capital investment.

Consequently, many vendors are turning to foreign markets. A substantial demand for modern bio-waste treatment technology is anticipated with the industrialization of the Asiatic NICs, headed by the People's Republic of China.

Test Your Knowledge: Backyard Dos and Don'ts

1. What kinds of materials can be composted?

a) weeds

b) wood chips

c) meat/poultry/fish scraps

d) answers a and b

e) all of the above

2. How large a space do you need for a backyard composting pile?

a) 3' x 3' x 3'

b) 6' x 6'

c) 3' x 6'

d) as large or small a space as you want

e) none of the above

3. Is it best to buy a compost bin or just have an open pile?

a) open pile

b) enclosed bin

c) both of the above

d) none of the above

4. Compost piles attract mice, rats and other animals.

a) true

b) false

5. The pile will emit foul odors.

a) true

b) false

6. You can compost during the winter in cold climates.

a) true

b) false

7. Compost can be used on:

a) lawns

b) container plants

c) landscaping

d) trees and shrubs

e) all of the above

1 - D. Weeds, bread, coffee grounds, fruit and fruit peels, garden clippings, leaves, sawdust, tea leaves, straw, sod, wet paper towels and wood chips all are safe and effective materials. You also can soak nd tear cereal and snack boxes to add to your pile. Butter, bones, cheese, chicken, meat or fish scraps, lard, pet manure, mayonnaise, milk, oils and sour cream should not be added.

2 - A. An effective home compost pile should be at least 3' x 3' x 3' to retain proper heat at its center. The pile should not be larger than 5' x 5' because proper air circulation may not be maintained.

3 - C. Backyard composters have several options. An open compost pile can be effective but is more susceptible to weather conditions. You also can buy or construct your own bin with wire mesh and a few metal stakes to anchor it to the ground. Bins can range from small, partially underground units to large tumblers that agitate organic matter by being rolled. Most bins are made from wood or recycled plastic.

4 - B. If you follow the guidelines on what you put in your pile - only include vegetable scraps, fruit peels and garden clippings - you shouldn't have pest problems. Pests are attracted by high fat and protein foods such as meat, oils, cheese, fish and poultry.

5 - B. If the pile is properly maintained, there shouldn't be odors. Microorganisms that thrive in environments without oxygen (anaerobic) tend to generate bad odors. Those that exist in oxygen-rich (aerobic) environments don't smell bad. You also can improve a compost pile's performance by turning it.

6 - A. Cold climates shouldn't affect the pile too much if it's properly maintained - decomposition may slow down, but the process will continue. Carbon-rich materials such as leaves, twigs and sawdust must be mixed in the pile with nitrogen-rich materials such as grass clippings and fruit peels. During the winter, cover the pile with a piece of plastic to keep it dry.

7 - E. Compost can be applied to lawns, gardens, athletic fields, shrubs and trees, plants, and used in landscaping as a light mulch alternative to straw. It improves the soil structure and helps retain moisture and minerals. In clay or sandy soils, it also increases porosity allowing roots to more easily penetrate soils and allow surface water to drain.

For more information, contact The Composting Council: 4424 Montgomery Ave., Ste. 102, Bethesda, Md. 20814. (301) 913-2885. Fax: (301) 913-9146. Website:

Appointments Med/Waste Inc., Miami Lakes, Fla., has been licensed by the New York City Trade Waste Commission to pick up and transport medical waste.

GAZ GeoEnvironmental Inc., Newton Upper Falls, Mass., has been named engineering technical services provider for Waste Management Inc., Houston.

SSI Shredding Systems Inc., Wilsonville, Ore., has been named exclusive supplier to the Tuas South Incineration Plant, Singapore.

Award Safety Vision Inc., Houston, has been ranked No. 298 on the Inc. 500, a national listing of the top privately held companies.