Water resources scarcity and aqueous environmental problems have become the bottle neck to limit the country’s social and economic development. Major sources of aqueous environmental pollution include point sources, e.g. industrial wastewater, municipal wastewater, and non-point sources like rural domestic wastewater and agricultural runoff. To address these problems, three major research areas are covered by the Department, namely municipal wastewater, industrial wastewater, and control and remediation of watershed pollution.
1、Theory and technology in biological treatment processes for municipal wastewater
Multiple choices are available for the treatment of municipal wastewater, among which biological processes are featured by their advantages of lower energy consumption, lower operational cost, and potential of total mineralization of pollutants. Therefore biological treatment is the primary choice for most municipal wastewater treatment facilities. In this area, we have conducted long term research and exploration, and have identified the following topics of interest:
1) Study on the mechanism of biological nitrogen and phosphorus removal, and the formation and transformation of cellular polymeric inclusions. For the first time, we elucidated the mechanism of cellular organic polymers formation under aerobic and non-nutrient limited conditions. Four research grants were awarded by agencies of provincial level or above, including the National Science Foundation of China, and several researches have been published by SCI and EI journals. Based on the fundamental knowledge obtained, a new technology “denitrification on intracellular carbon source” has been developed, and successfully applied for national patent.
2) New technology development for high efficiency, low energy consumption anaerobic treatment for municipal wastewater under ambient temperature. To address the problem of high energy consumption in biological municipal wastewater treatment, in-depth study was conducted into the mechanism of anaerobic processes. High efficiency anaerobic reactors were developed, and coupled with the utilization of clean energy, the operation of anaerobic digesters in winter has been much improved. New technology has been developed suitable for treatment of low strength municipal wastewater under ambient temperature, and one research grant has been awarded under National “863 Plan” as a sub-project.
3) Operation study and optimization of large scale wastewater treatment plants: studies include the mechanism of EPS accumulation and its influence on treatment effect in real biological processes; flow pattern in new treatment constructions (e.g. baffle reactors); operational characteristics and optimization of new processes (e.g. 3 pass oxidation ditch); development of stimulation software suitable to the operational conditions and influent water quality in China’s municipal wastewater treatment facilities, to facilitate decision making in retrofit and scaling up of the plants, and their long term efficient and complying operation; treatment and reuse technologies for wastewater and online control systems. One NSFC fund and six projects from large treatment facilities have been granted, and real operational problems have been addressed in Shanghai Zhuyuan municipal wastewater treatment plant (170 m3/d), Shanghai Petrochemical Company water purification plant, and Shanghai Baosteel water purification plant.
4) Application of molecular microbiology in biological treatment processes: the abundance and distribution of microbial populations such as nitrifiers, dinitrifiers, PAOs,and GAOs in biological nutrient removal processes have been analyzed with molecular biology means; strains in anaerobic systems with the function of degrading toxic and harmful organic substances have been isolated and purified; fundamental knowledge has been obtained on molecular level regarding the mechanism of biological nitrogen and phosphorus removal, to support both the development f new bioreactors and operation of large treatment facilities.
2. New technologies development and integration for municipal and industrial pollution treatment and remediation
Fast developments in modern municipal and industrial sectors are accompanied by the production of huge amount of pollutants, which include domestic wastewater and wastewaters from various mining and manufacturing processes. The problems of particular concern are the high strength, recalcitrant and toxic waste streams and sludge. In addition, historical discharge has caused severe accumulation of pollutants in both water and soil environments. To address these concerns, this direction mainly covers the areas of water treatment science and engineering, industrial waste treatment and utilization of biomass resources, and remediation of polluted environments. The focuses include (1) fast start-up, stable operation, pollutant transformation, and application and commercialization of aerobic and anaerobic granular sludge technologies; (2) development of high efficiency and low cost technology for industrial wastes conversion to energy; (3) reaction mechanism study, process simulation and application development of novel types bioreactors; (4) treatment and bioremediation of heavy metal and organics pollutions in soil; (5) schematic design and new technologies integration for industrial wastewater and sludge.
3. Integrated Watershed Pollution Control and Remediation
Most of China’s social and economic activities take place in watersheds, which have undergone serious ecological destruction and environmental pollution. Chinese government has been shifting its water pollution control strategy from the traditional “end-of-pipe” approach solely emphasizing technology and engineering towards an integrated watershed approach. We aim to establish an integrated technology system for watershed pollution control under three guiding principles: (1) controlling pollution from the source; (2) reduction during transport; and (3) intensive treatment in priority areas. So far, we have developed a series of watershed pollution control technologies that meet the special needs of Chinese national conditions
1) Rural Sewage Treatment
Effective rural sewage treatment has different requirements from municipal sewage treatment. On the one hand, it is hard to adopt a centralized approach for rural sewage treatment because of scattered settlement and scarce pipe network in the rural regions. On the other hand, there is a lack of financial, technical, and managerial support for complicated sewage treatment technologies. The research team has developed two promising technologies that are tailored to the characteristics of rural sewage: the Tower Earthworm Ecofilter System suitable for relatively concentrated rural households and the Soil Capillary Infiltration Ditch System for remotely located households. Both technologies have the advantages of low cost and easy maintenance.
2）Rural Waste Reuse and Recycling
Rural waste is one major non-point pollution source in China, which includes crop straws, wastes from animal feedlot operations, and domestic garbage. The research team has developed an anaerobic co-digestion technology for producing biogas from crop straws, which could improve the process’s biological conversion rate from 40% to 70%. Residues from the digestion process could be used to produce high-quality organic fertilizers. In addition, an well-mixed anaerobic digester has been developed to dispose the wastes from large concentrated feedlot operations, solving their dilemma of waste disposal and resource recovery. Finally, a series of technologies for simultaneous treatment of rural sewage and disposal of solid wastes have also been developed.
3) Advanced Treatment of Mildly Polluted Water
Mildly polluted water is discharged from both point (such as discharge from municipal sewage treatment plants) and non-point (such as agricultural runoff) sources. Due to the severe lake eutrophication situation across China, mildly polluted water, if discharged directly without advanced treatment, would aggravate the nutrient enrichment of water bodies and exacerbate their eutrophication conditions. The research team has developed a series of technologies for the advanced treatment of mildly polluted water. For example, biological filters and constructed wetlands have been used for the advanced treatment of discharge from sewage treatment plants. Local landscapes and river networks have been utilized and fortified with various structures such as riparian buffers, ecological ponds, and constructed wetlands for the interception and treatment of mildly polluted water.
So far, the research team has presided a dozen national, provincial, and ministerial projects in integrated watershed pollution control, including three National Science Foundation (NSF) projects, two 863 projects, and one National Key Project in Water Pollution Prevention and Control. Many demonstration projects for integrated watershed pollution control have been successfully completed. In the following are some examples:
1)National Key Project in Water Pollution Prevention and Control: Rural sewage treatment, reduction of nitrogen and phosphorous loads, and project demonstration in the Wujingang watershed
2)Sub-project of the Lake Tai Project under the National Plan of Research and Development in High Technology (the 863 Plan): Rural sewage treatment technologies and project demonstration.
3)Zhenjiang Water Environment Project under the National Plan of Research and Development in High Technology (the 863 Plan): Technologies for building biodiversity and constructing riparian zones
4)Jiangsu Province’s Lake Tai Water Pollution Control Project: Demonstrations of using the Tower Earthworm Eco-filter System for rural sewage treatment
5)Jiangsu Province Science and Technology Supporting Program (Agriculture): Technology demonstration for rural sewage treatment at Taicang City