Research on Nitrogen and Phosphorus Removal Efficiency and Carbon Emission Characteristics of MBR Process with Low DO Condition
To enhance the efficiency of nitrogen and phosphorus removal and promote the green and low-carbon development,based on the W wastewater treatment plant,the path to reduce the energy consumption and carbon emission intensity of membrane bioreactor(MBR)treatment of domestic wastewater was studied,and the impact of low dissolved oxygen on nitrogen and phosphorus removal was analyzed.The mechanism analysis was conducted in combination with microbial characteristics,and the carbon emission intensity was calculated.The results showed that by dynamically adjusting the dissolved oxygen(DO)in the aerobic zone,maintaining the DO concentration at about 0.5 mg/L and synchronously adjusting the reflux ratio,the effluent quality can reach the local standard stably,and the removal efficiency of TN and TP increased by about 10％and 8％,respectively.The main reason was that the ORP in the anaerobic zone was lower under low DO,and phosphorus release was more sufficient.At the same time,the proportion of denitrifying phosphorus removal bacteria was increased,and the denitrifying phosphorus removal effect was significantly enhanced under this condition.The carbon emission intensity calculation showed that under the low DO,the total carbon,direct carbon and indirect carbon emission intensity decreased by 0.342 kgCO2/m3,0.031 kgCO2/m3 and 0.373 kgCO2/m3,respectively.The increase of direct carbon emission intensity was mainly due to the better and more stable outflow quality,and the increase of direct emissions of N2O.The contribution of the reduction of carbon emission intensity was mainly from the reduction of power consumption in the process of indirect carbon emission.
Sewage treatment plantMBR processlow DOnitrogen and phosphorus removalcarbon emission
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