Study On Energy Consumption And Energy-Saving Approaches Of A Municipal Wastewater Treatment Plant Of ZiBo

In recent years, with water pollution becoming more serious, the construction of wastewater treatment plant(WWTP) has also been developed rapidly, however, because of high energy consumption of WWTP operation, some of the WWTPs have a lot of problems such as operation cost deficiencies, sewage treatment facilities not working properly. Therefore, research on the energy saving measures of WWTP to decrease the cost of sewage treatment is of important and practical significance. This paper mainly analyzed the operation and energy consumption situation of a WWTP in Zibo city, summarized the main features and levels of energy consumption of sewage treatment plant units, concluded energy saving measures that each unit could adopt, at the same time, it analyzed the feasibility and effect of energy saving measures, provided reference for the similar WWTP of energy saving work.Industrial wastewater is the main influent source of this WWTP, influent quality shows that concentration of COD is from 350 to 500 milligrams per liter, concentration of ammonia nitrogen is from 35 to 45 milligrams per liter, concentration of suspended solid is from 300 to 500 milligrams per liter, the sewage treatment project uses A~2/O process, water quality of effluent can reach Standard A of the first class, power consumption of per ton water is 0.281kWh/m3 on average, which is slightly lower than that of general WWTP. Electricity is the main component of direct costs of production, accounting for 60% at least; Energy consumption of each process unit from high to low is biochemical treatment unit(accounting for 55.85%), pretreatment unit(accounting for 22.6%), deep processing unit(accounting for 12.4%), sludge processing unit(accounting for 9.l5%); Main power consumption equipment of each process unit is influent pump, blower, secondary lift pump, centrifugal dehydrator, accounting for 20.3%,38.7%,8.46%,8.25%, respectively.Key equipment of the WWTP is the vital point of energy conservation. By changing the impeller diameter of influent pump, operating blower automatically controlled by the dissolved oxygen, discharging excess sludge combined to improve the solid content, effect of energy saving is obvious. After adopting various energy-saving measures, power consumption of per ton water reduce by 15% on average, among which, power consumption of per ton water reduces 0.0012 kWh/m3 by transforming the water pump; gas/water ratio is changed from 3.5 to 2.85 on average after controlling dissolved oxygen automatically, power consumption of per ton water reduces 0.012kWh/m3 after excess sludge processing combined, solid content being into dewatering machine is changed from 6.4% to 10.9%, power consumption of per ton water reduces from 0.025 kWh/m3 to 0.021 kWh/m3 on average. After the modification is done, power consumption of per ton water dropped to 0.239 kWh/m3 averagely reducing 0.042 kWh/m3, operating cost reduced 1.49 million RMB every year achieving a great effect.