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2.4.06 Transferable solutions for special wastewater problems – paper manufacture at the Yellow River

Paper factories are of great economic importance to the Chinese province of Shandong. However, the wastewater production of these factories is extremely high. A new research project supported by the BMBF has examined ways of making China’s paper production more environmentally sustainable.

The Shandong province in the east of the People’s Republic of China accounts for the second highest GDP of all Chinese provinces – and most of this can be attributed to the industrial operations based in the region. These primarily include paper manufacture, distilleries, dye industry and monosodium glutamate production. The Shandong province has long suffered problems with its drinking water supply. In 2003, more than two million people did not have an adequate supply of drinking water. According to the annual report of the Shandong Ministry of Water Resources, more than six million people were without a short-term supply of drinking water, despite the relatively high level of precipitation experienced in 2003. As a result, the problems with the province’s drinking water supply are likely to increase in the coming years.

China’s second largest river – the Yellow River – flows through the Shandong province. Water is channelled from the Yellow River into the “south-north transfer”, particularly to supply the Beijing region with untreated water for drinking water production. In this context, the establishment of sustainable water resource management in the basin of the Yellow River and the transfer is a very important topic. Consequently, a large number of projects have been initiated to tackle this matter. The focus of these initiatives is on the cleaning of industrial wastewater from, for example, distilleries, textile dye works and paper factories in particular.

In 2005, 38 paper factories in Shandong were using straw as a raw material. The wastewater produced by these factories – 416 million cubic metres in 2000 alone – is extremely damaging to the province’s waterways. A production output of some three million tons of paper in 2000 equates to 138 litres of wastewater per single kilogram of paper – by way of comparison, German paper factories produced a mere tenth of this.

To ease the conflict between economic growth and environmental protection and gradually achieve all environmental goals, both the central government in Beijing and local government of the Shandong province issued stricter regulations concerning industrial wastewater disposal. As of 1 January 2011, wastewater fed directly into the receiving waters must not exceed a concentration of 100 mg COD/l (“Integrated Wastewater Discharge Standard in Shandong Peninsula Basin”). This discharge limit is lower than its European counterparts. This made it all the more impossible for the wastewater treatment plants in the Shandong paper factories to meet these requirements, both with regard to the polluting load and the pollutant concentration. It was therefore necessary to develop processes that would allow the factories to comply with the stipulated discharge loads and concentrations in a reliable and cost-effective manner.

Iron bed (foreground), intermediate treatment and final clarification (background)

Iron bed (foreground), intermediate treatment and final clarification (background)
Iron bed (foreground), intermediate treatment and final clarification (background)
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The overall aim of the commissioned research project was to identify purification solutions for the special paper wastewater of the Shandong province and to make initial improvements to general wastewater treatment. Another long-term goal was to optimise process water recirculation to reduce the overall water consumption in Shandong’s factories. The project was also to assess the transferability of the examined procedures to other paper factories in the Shandong province and throughout China.

The initiative can be split into two main steps: in the first part of the project (project phase A), the micro-electrolysis procedure was examined on a laboratory scale at the Technische Universität Darmstadt (Darmstadt Technical University) in order to optimise the biodegradability of wastewater from paper production. The aim was to achieve significant BOD5 and COD reduction and improve biodegradability in subsequent stages. This step supported the later research in the semi-industrial test facility (project phase B), which had been constructed in Shandong’s Qufu factory as part of the Sino-German joint venture.

In the semi-industrial test facility, the paper wastewater was processed in a pre-treatment stage based on the micro-electrolysis procedure and a two-stage biological cleaning process (anaerobic /aerobic or aerobic/aerobic). The micro-electrolysis was used to pre-treat the wastewater, particularly to eliminate lignin compounds, degradation of which is very difficult. In a first basin, the wastewater was then processed in a highly concentrated activated sludge procedure and a subsequent biofilter stage. In the second basin, the wastewater was subjected to anaerobic pre-treatment with a UASB reactor and subsequent aerobic post-treatment using a biofilter. In addition to the semi-industrial test facility, project phase B also involved additional laboratory experiments with a modified treatment stage, in which the various treatment steps were processed in the following sequence: micro-electrolysis, UASB, activated sludge basin and biofilter.

In their tests with the semi-industrial facility, researchers were able to meet the 120 mg COD/l threshold applicable from 1 January 2010, but not the more stringent emission standards that would take effect in 2011. However, the additional laboratory experiments succeeded in reaching these future requirements (less than 100 mg COD/l).

The conducted research showed that it was possible to optimise the wastewater treatment in China’s paper factories by affordable means; however, meeting the required pollutant limits would require the adaptation of procedures to the special wastewater streams and polluting loads. With regard to the transfer of results to other factories, researchers are currently still working on a water balance for the paper factory specified above However, the general assumption is that the employed procedures will be suitable for factories using straw as a raw material. In order to assess suitability for the paper wastewater treatment of factories using other raw materials, consideration and possible further examination of the specific conditions and wastewater composition is required.

Technische Universität Darmstadt
IWAR Institute
Department of Wastewater Technology

Prof. Dr.-Ing. Peter Cornel.
Petersenstraße 13
64287 Darmstadt, Germany
Tel.: +49(0) 61 51/16-21 48
Fax: +49(0) 61 51/16-37 58
E-mail: p.cornel@iwar.tu-darmstadt.de
Internet: www.iwar.bauing.tu-darmstadt.de
Funding reference: 02WA0953
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