| With the leapfrog development of Chinese industry, water pollution caused by industrial issues has seriously hampered the contemporary economic development and serious threats to the people’s health. The wastewater, generated in the process of manufacturing petroleum cracking catalysts, contains a large amount of ammonia and suspended solids. The currently process of wastewater treatment has the problem of high aeration energy consumption, the amount of alkali dosage, high operation costs, high capital costs, low removal efficiency of nutrients(N), et al. For petrochemical enterprises, the problem of how to efficiently pretreat wastewater and denitrification are needed to solve. Petroleum cracking catalyst wastewater as the research object, the optimum operating parameters of pretreatment of electrocoagulation(EC) was studied. The start-up parameters, the nitrogen removal characteristics of CANON process were investigated with the pretreatment process of electrocoagulation(EC). Analog seasonal temperature changes of sewage treatment plant, the performance of the reactor affected by the temperature changes was researched. It also studied economic benefit evaluation of the integrated process and current wastewater treatment process.Results showed that: EC had great advantage in treatment efficiency, fighting against fluctuations of raw water quality, reducing the loading rate on subsequent biological treatment unit. The optimal parameters were p H of 9.0, 1.5cm of electrode distance, current density of 25 m A/cm2 and 25 min of electrolysis time, treating petroleum cracking catalyst prodution wastewater. Under the optimal experimental conditions, the quality of effluent was high by the pretreatment of electrocogulation, and the removal rates of COD and turbidity were up to 30%, 97%; the main cost of EC was the aluminum loss, which was 0.0935kg/m3 and accounted for 59.57% of the total cost.CANON process was started by the addition of nitrification sludge into EGSB anaerobic ammonia granular sludge oxidation reactor, under the condition of micro-oxygen aeration. Under the condition of T(30±0.5)℃, DO(0.5±0.05)mg/L, p H7.5~8.2, CANON process was start-up, successfully. TN removal efficiency was 62%, and TN removal rate of was 0.189 kg N/(m3?d). Applying EC-CANON process to treating petroleum cracking catalysts wastewater, COD removal efficiency achieved 60.03%, the average total nitrogen removal efficiency was 67.3% and the average total nitrogen removal rate was 0.07 kg N/(m3?d). The concentration of COD and ammonia of effluent of EGSB was less than 100 mg/Land 10 mg/L.Simulating the change of seasonal temperature of sewage treatment plant, operation performance of combined process was researched under different temperature conditions(28, 30, 33 ℃). The results showed that: under different temperature conditions, the effluent quality of combined process could meet the emissions standards of petrochemical enterprises. Compared with 28℃, 30℃, under the conditions 33℃, the nitrogen removal efficiency of CANON process was the highest. Ammonia removal load was mean to 0.14 kg N/(m3?d) of average value.Total nitrogen load is relatively high, up to 0.15 kg N/(m3?d), 0.12 kg N/(m3?d) of average value, total nitrogen removal rate was 67.6% of average value.Engineering economic analysis showed that: compared with the current treatment process of sewage treatment plant, EC-CANON process has a great advantage in the capital costs and operating costs, which could reduce the floor space of 1740m3, save 64.67% of project cost, cut down 3.74 million RMB/a of operation costs. It is a very promising treatment process. |
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