A Case Study On The Sewage Treatment Technology Of Shandong Dongming Petrochem Group

With the development of the national economy, the demand of water in industry, agriculture and daily life is increasing. It brooks no delay to protect our limited water resources and save water. With the development of science and technology, the wastewater treatment technology is also developed and innovated. The national environment policy was deflation in 2007 and a higher requirement was put forward in local standard of Shandong province (DB37/599-2006) based on the strictest requirements of the national standard. Shandong Dongming Petrochemical Group -one of the pollutant discharging units along the East-Route of South-to-North Water Transfer Project, has the unshirkable responsibility and obligation in transforming the existing wastewater treatment technology, improving the wastewater treatment efficiency and enhancing resusing proportion of reclaimed water under the background above. The group has achieved good economic and environmental benefits by increasing the investment in environmental protection.The reconstruction project of wastewater treatment technology of Shandong Dongming Petrochem Group is studied in this paper. Numerous examples of petrochemical wastewater treatment and the application of new technology at home and abroad were referenced. The reason that the CODcr and ammonia nitrogen is not meet the standard before the transformation of technology is analyzed based on the principle of sufficient utilization of the existing facilities, comprehensive consideration and adaptation to local conditions. The problems and its reasons existing in the flotation section and the biochemical section is analyzed deeply. Particularly, some optimizing and transforming measures of technology of biochemical section are carried out. So the thesis provides some source materials and experience for technological development of wastewater disposal in the petrochemical industry. The reconstruction project is a successful project and it improved the wastewater disposal ability of Shandong Dongming Petrochem Group and made its discharged water meet the standard of Comprehensive Discharge Standard along Shandong South-to-North Water Transfer Project. Take the main pollutants in discharge water as example, before the technical transformation, the indexes of CODcr and ammoniac nitrogen are respectively over 120mg/L and 40mg/L; but after the transformation, they are respectively under 40mg/L and 1mg/L. Moreover, the result of the detection of COD and ammoniac nitrogen in discharge water during Feb. 19 to Mar. 25, 2008 also shows that the indexes of COD and ammoniac nitrogen in discharge water after transformation are under the specified value of Comprehensive Discharge Standard along Shandong South-to-North Water Transfer Project. Therefore the transformation is a successful one with good effect and right processes. The transformation also lays a good foundation for the the recycling of wastewater and the increase of the group's economical and social benefits.The innovation lasted for more than one year with the old disposal processes completely abolished and sour water stripping units constructed. A lot of new technology and new processes in petrochemical wastewater treatment were also introduced. They are: 1) replacing the original A/O2 process with double HO process; 2) newly constructed up-flow biological aerated filter; 3) removing COD and ammoniac nitrogen in secondary biochemical effluent in order to standardize the discharge water; 4) changing the anoxic pond into two-state hydrolysis-acidification pool; changing the horizontal-flow water distribution into up-flow; 5) enhancing the bioavailability of activated sludge in aeration pond to improve the adaptability and anti-shock loading capability of flora; 6) adding biological preparation into plug-flow pond: before the biological preparation added, the secondary aging sludge was reduced by one third, and during the adding process, the DO in plug-flow pond was controlled to suitable concentration; 7) controlling the nutritive ratio of C:N:P in microorganism; 8) introducing Advanced Wastewater Treatment Process—the process of biological activated carbon. By these measures, the insufficient ability and inadequate treatment of the water in the original wastewater plant was solved radically.This innovation has an extensional significance, fitting for the global development of the era and the development of the group. The Group has economically benefits from the transformation. Sour water stripping unit alone can produce 59.6 ton of purified water, 0.38 ton of sour gas and 1.79 ton of industrial ammonia. And the recovery of sulfur is up to annually 20,000 ton. What's more, the renovation of wastewater is also implemented. Now the treatment of 200 ton of wastewater per hour is realized. About 30% of the water is for greening and washing, and the others is discharged to reach standard. Besides the economical benefits, the transformation also brought enormous environmental benefits: the emission of COD is 41.84 ton, with 162 ton lower than that of last year. Therefore, the wastewater treatment has got remarkable achievement.At present, Shandong Dongming Petrochem Group prepares to construct the membrane wastewater treatment process to recycle the treated wastewater into the production. This technical transformation has laid a good foundation for the realization of zero-emission. The case of wastewater transformation studied in this thesis has practical significance on the industry of petrochemical wastewater treatment in the application of new technology and new process.