Research On Problems Facing And Technology Optimization Of Coal Chemical Industry Wastewater Treatment Technology

With the rapid development of coal chemical industry and gradually enhanced environmental protection consciousness in our country, the improvement of social awareness, tighten of the environmental policy,and increasingly strict demands for treatment effect,these all making wastewater treatment become the key factors. Most running typical coal chemical projects are all for demonstration. Although reports or research for a specific project or one particular treatment are numerous, but research on present situation, the facing problems and optimization measures and effect for whole wastewater treatment process of the coal chemical industry has a large gap, no matter considering from the depth, breadth, and the amount. In view of the present coal chemical wastewater treatment is still more chaos, this study based on field survey of the national level of large-scale typical coal chemical projects, and to gain the authentic big data of the operation, then processing and analyzing the data to see the current situation of wastewater generation and treatment, summarize the common problems facing. Finally, the corresponding optimization solutions are put forward, and provide references for existing and new projects.The content mainly includes four parts: source apportionment, analysis of processing status, the problems facing and technology optimization methods.The results of source apportionment for processing, non-recurring, containing salt and high salt wastewater 4 classes, a total of 21 kinds of wastewater showed that: the difficulties and key issues of the current wastewater treatment is the conclusion of broken coal pressure gasification wastewater treatment, for which has largest water quantity, quality and fluctuations; Quantity of containing salt wastewater is 2-5 times to biochemical wastewater, TDS is about 1,000-5,000 mg/L; High salt water accounts for 10-40% of salt water, TDS is about 10,000-50,000 mg/L; The salt sources of containing salt wastewater contains raw water, raw material coal and wastewater of production process and medicament added between treatment process.Based on the field survey data, described the processing status from five parts of phenol ammonia recovery, gas pretreatment, biochemical processing, deep processing, recycling treatment and high salt water treatment: Process of "first deamination again removing phenol", and use ketone(MIBK) as extraction solvent, both improved the phenol ammonia recovery effect; Air flotation process design should pay attention to the oil content match with the actual value; Biochemical treatment using "anaerobic + multistage aerobic" process more, who’s HRT was set higher than 100 hours, but it’s hard to keeping stable operation; "Ozone + BAF" is the most commonly used and the relatively mature process in advanced treatment. Reuse treatment commonly using " ultrafiltration + reverse osmosis method" process; Evaporation crystallization technology of high salt wastewater can realize zero discharge of the "water", But the fractional crystallization salt process and the resource utilization of those salt needs further engineering verification.Starting with the wastewater treatment of 10 typical projects including type coal-to-gas, coal-to-oil, coal-to-olefin and else, to find the main problems existing, and then summarized the common problems of coal chemical industry wastewater treatment in our country as follows: Total phenol of domestic phenol ammonia water content is generally higher than 500-600 mg/L; Air flotation effect of special high oil-bearing water is poor; Treatment effect is not stable, the effluent is not up to the standard, advanced treatment effluent COD, ammonia nitrogen concentration of most enterprise respectively between 100-200 mg/L, 15 to 20 mg/L or higher; Part of the olefin project did not set evaporation crystallization device, so its water reuse rate less than 80%; The production of crystalline salt is large, lack of resources way s, and the annual treatment costs in order to 100 million; Poor equipment reliability and foam and odor control problems.In view of the common problems described above, this research took "Chinacoal Erdos Energy & Chemical Company Limited" as the research objects, which the wastewater treatment system has been kept a long-term stable operation there. Studies have shown that: Special design of nitrogen gas float, EC tower, BE pool, improved multistage A/O process combination optimization, which has been achieved 26 months of stable operation in broken coal pressure gasification wastewater treatment; Through supplements BE pond sludge concentration, additive co-substrates, increasing water back rate, the problem of effluent COD increases can be effectively solved, and the actual effluent COD concentration below 100 mg/L; Optimization of phenol ammonia recovery process, adding the organic and inorganic carbon source can recover ammonia nitrogen treatment effect, effluent ammonia nitrogen concentration stably keeping less than 2 mg/L.This study has established the produce source point, water quality and quantity of kinds of modern coal chemical industry wastewater, summarized the present situation in whole wastewater treatment process of coal chemical industry wastewater treatment technology in China, analyzed the common problems are facing now, Finally gives the technology optimization method which the company has taken aim at these common problems, and come to the conclusion that the optimization technique is feasible, the effect is obvious. The above experience can provide a powerful reference for the planning, design and operation of the wastewater treatment in other built and under construction coal chemical projects.