German Composting Grabs International Attention

By John Denlay Composting Feature reprinted from Waste Management and Environment Nov 1992

With up to 1% of municipal waste in Australia being lead, there's definitely room for strong initiatives from local government and state environment protection and waste authorities in organising recycling. The system described in the following article has appeal for all household recyclers (often women and children) and would-be recyclers.

The Germans are getting quite a name in waste minimisation - recyclable cars, refillable P.E.T. bottles and radical new packaging laws. Lesser known, though possibly more important, are the German's composting initiatives.

The Germans have a long, though chequered history in composting. Faced with landfill shortages in the 1970s, numerous mixed waste composting plants were established. Plagued with operational problems and contaminated compost which could not find markets, this quick fix solution soon fell from favour.

After efforts failed to clean up the mixed waste compost by collecting recyclables separately. The Germans realised clean compost could only by produced when the organic materials are collected separately.

In 1982, the village of Witzenhausen was the first to put this into practice. Each household was given an additional 240 litre bin for food and garden materials. Mixed waste and organics are collected on alternate weeks.

The compost produced from separately collected organics meets the compost market's demands of low contamination - in particular, heavy metals, glass and plastics.

Witzenhausen's clean compost renewed German interest in composting. In the last decade, 88 source separated collection programs have been introduced, experimenting with a range of collection systems.

Consistently good results have been found from these programs. For single houses, 70-80% of organics are separated with contamination as low as two to five per cent. Even in the difficult task of collecting food waste from apartments, an impressive figure of 50% separation is obtained.

The German's advances in collection systems are matched by their developments in composting techniques. The open windrow is now only one of a wide range of options available.

A low-cost technique, mattress composting, involves large mats of thinly spread garden materials built to a height of three metres. The material is occasionally loosened during a period of three to four months after which it is piled into tall windrows for a further two to three months.

Enclosed composting systems include rotating vessels and stationary systems. Box composting is a stationary system which involves modular "containers" in which the decomposition is controlled through forced air.

Anaerobic composting is attracting considerable interest. Its main advantage is the capturing of the energy content in the organics through the collection of methane. Proponents claim the energy recovery from organics in anaerobic composting exceeds incineration.

Of all the advances the Germans have made in composting, the country's market creation initiatives are possibly of most significance.

To avoid the situation of compost quality not meeting end user requirements, a co-operative of compost producers and users was formed. This Federal Compost Quality Assurance Organisation - Bundesgutegemeinschaft Kompost - e.V., has set quality criteria for compost which meets the needs of users and is achievable by existing composting techniques using source separated feedstocks.

The Organisation provides a certification for compost quality (see logo). On-going independent monitoring of quality is built into the certification; a feature which gives users confidence in the product. Any compost not meeting the quality criteria will have a hard time finding a market.

Governments have played important roles in these developments. On state, Hessen, has issued a directive requiring all communities to have composting facilities by 1995. The Federal Government is considering legislation which would limit the organic content of waste landfilled to only five per cent.

Governments are also working on national standards for compost quality and compost use. According to the German Federal Environment Agency, these standards will be the first step towards an overall legislation to control input of contaminants to German soils a "soil protection law".