Performance of Packing-Anaerobic-Aerobic Digestion and Composite Enzyme Processes for Urban Wastewater Treatment and Sludge Reduction
In response to the increasing requirements of current municipal wastewater treatment,as well as the large amount of sludge produced by the wastewater treatment process which brings difficulties to the subsequent sludge treatment and disposal.This study aimed to develop a sludge reduction technology that could reduce the sludge yield and ensure the sludge settling performance while safeguarding the effluent treatment effect.The sludge reduction effect of aerobic-sedimentation-anaerobic(OSA)process and filler-anaerobic-aerobic digestion process with and without the addition of highly efficient lytic composite enzyme treatment,as well as the removal efficacy of organic matter and nutrient salts from sludge supernatant were investigated through comparative operation tests under constant temperature.The results showed that the sludge reduction rate of the packing-anaerobic-aerobic digestion and complex enzyme process could reach 44.0%after 6 days of the digestion process,with the best sludge reduction effect.In addition,the process could maintain the dissolved chemical oxygen demand(SCODCr)from 180 mg/L to 200 mg/L,the pH value was maintained from 6.8 to 7.0,ammonia nitrogen was maintained from 3 mg/L to 4 mg/L,and NO3--N was maintained from 36 mg/L to 43 mg/L,so to ensure the effluent water quality.Meanwhile,the sludge volumetric index(SVI)value without obvious changes,which ensured the sludge settling performance.