Progress is certainly being made in waste-water treatment in China. According to official statistics from the country, last year 57 percent of the waste water generated in the cities was treated. However, more treated waste water means more sludge, and so far in many places in China there is still no suitable way of using or disposing of this material. A clear picture of the problem is presented in a recent report carried out in seven large Chinese cities by German consulting companies. This initiative was funded by the German Ministry for Economic Cooperation and Development (BMZ) via the 'Kreditanstalt für Wiederaufbau (KfW)'. The report states that standard practice so far in parts of China has been to simply deposit the sludge on waste dumps – a method that is reaching its limits because of the high water content of the material and the resulting instability of the mound. The reason why sludge in China is so liquid is because of inadequate dewatering and drying, often the sewage plants in China only have band filter presses or centrifuges which reduce the water content to only 75 percent or even 80 percent. And this is too moist for a substrate that can be sensibly disposed of.
Nor is it feasible in many cases to use the sludge as a fertiliser in agriculture, because of the material often contains a high level of harmful substances. The poisons come mainly from industrial waste water, this is mixed with the sludge in the cleaning process. One result of the unsolved disposal question is that intermediate depots are created, often on the site of the sewage plant itself. Many of these plants have now reached their capacity limits here. Some operators have now gone over to tipping the awkward material back into the rivers or into the sea. From an ecological and in the end also an economic point of view, this is an untenable situation – and yet this is just the start of the landslide of sludge that is moving towards China´s waste-water economy. The country's eleventh Five Year Plan sets out that the treatment ratio for waste water in 656 cities will rise to 70 percent by 2010. Assuming that each person generates around 300 grammes of sewage per day (with 80 percent water content), the figure for the amount of sewage sludge produced in the country each day works out at over 150,000 tonnes.
According to the experts who worked on the KfW report, the main reasons why Chinese sewage plant operators have so far not implemented a sustainable system of sewage-sludge disposal are legal uncertainties, a lack of technical expertise and a lack of clear funding models. The industrialised countries of the world, above all Germany, are supporting China in its search for sensible solutions. At the end of June this year, for example, the 'KfW Entwicklunggsbank' and the Chinese National Development & Reform Commission organised a bilateral workshop in Beijing on sustainable sewage-sludge disposal. The German Environment Ministry also took part. At this workshop it became clear that there would probably be no one standard solution for the sludge question in China, but a mixture of ideas involving dumping, agricultural use and thermal applications. For the sludge to be suitable for dumping, a further reduction of the water content is necessary, using modern system components such as chamber filter presses.
Many participants in the workshop regarded co-combustion in coal-fired power stations, in cement works and in waste-incineration plants as a suitable method of using the sludge. In particular the use in power stations represents tremendous untapped potential, in view of the several hundred coal-fired power stations in China. A prerequisite here, however, from an ecological point of view, is the use of high-performance flue gas dust collectors.
Germany is a world leader in technology for sewage sludge treatment and waste incineration. In November this year the German Ministry of the Environment is organising an information visit to Germany for Chinese decision-makers, so that they can view these systems and plant in action.
IFAT CHINA is the trade fair in Asia covering an extensive range of practical solutions in the areas of water supply, sewage, waste disposal, recycling, air pollution control, environmental technology and natural energy sources. The exhibition offers an effective business and networking platform for Chinese and international professionals in the environmental sector and is accompanied by a first-class technical-scientific conference program. IFAT CHINA 2006 attracted 284 exhibitors from 25 countries, and approximately 10,000 visitors from 66 countries. The 3rd International Trade Fair for Water, Sewage, Refuse, Recycling and Natural Energy Sources is taking place at the Shanghai New International Expo Centre (SNIEC) in China from 23 - 25 September 2008.
Messe München International (MMI, Munich Trade Fairs International Group) is one of the world´s leading trade-fair companies. It organises around 40 trade fairs for capital and consumer goods, and key high-tech industries. Each year over 30,000 exhibitors from more than 100 countries, and over two million visitors from more than 200 countries take part in the events in Munich. In addition, MMI organises trade fairs in Asia, Russia, the Middle East and South America. With six subsidiaries abroad - in Europe and in Asia - and with 66 foreign representatives serving 89 countries, MMI has a truly global network.