| The effluent of the membrane bioreactor (MBR) treating the hospital wastewater is good in quality, but the membrane interception can keep the microorganism of the mixed liquid in the reactor. Taken the sludge of the MBR as the object, this aim of the study was to evaluate its characteristics, its disinfection characteristics and its disinfection by-products used sodium hypochlorite and peracetic acid as disinfectants and the sludge reduction.The experimental results indicated that the content of total count, total coliform and faecal coliform in the MBR settling sludge is slightly bigger than that in the supernate. Through the analysis of kinetics the rate of the apparent production coefficient Yobs was 0.118-0.132 kgMLVSS/kgCOD, which is below that of the conventional activated sludge system. MBR is a process of the sludge reduction as well as one of the highly effective sewage treatment technologies.Sulfuric acid, acetic acid, hydrogen peroxide (analytical grade) were used conveniently to produced peracetic acid with its content of approximately 18%. The decomposition of the peracetic acid and the H2O2 conformed to one-grade formula of reaction kinetics, and the half-life is 41.01d and 51.7d, respectively. The temperature has great influence on its stability.The two disinfectants, sodium hypochlorite and peracetic acid,are effective to the disinfection of MBR sludge, and the former is slightly better than the latter. When the concentration of effective chlorine and peracetic acid were 600mg/L and 800mg/L, the lg removal rate of fecal coliform for the former was 4.97-6.03 and that of peracetic acid was 5.02-6.06 after 1h reaction, which ensured that the remaining fecal coliform met the requirement of Discharge standard of water pollutants for medical organization (GB18466-2005), the remainders of the two disinfectants were 19.23 mg/L and 103.33mg/L,respectively. The disinfection of sodium hypochlorite and peracetic acid mainly occured in the first 10min. MLSS had bad effect on disinfections of the two disinfectants, the former is worse than the latter. The disinfecton of total count, total coliform and faecal coliform with two disinfectants accords greatly with Collins-Selleck Model, which reflect the lag and tailing of the disinfection.The main disinfection by-products of sodium hypochlorite were CHCl3. When the chlorine concentration is 600mg/L, THMs is about 9631.6μg/L, and CHCl3 9510.2μg/L after 1h contact time. The disinfection of the peracetic acid did not produced haloform obviously.The deactivation rate of microorganism in the MBR sludge present correlational dependence with the content of nucleic acid. The dissolution rate of MBR sludge used peracetic acid of 100mg/L can achieves 15.3% in 3h.
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