The Experimental Study On Treatment Of Printing And Dyeing Wastewater With A Hydrolysis-Membrane Bioreactor

Printing and dyeing wastewater from the textile industry contains a wide variety of chemicals which has high color, pH and difficult to be treated. Due to its harm to environment and human body, more and more attentions are paid to its treatment. And the treatment of printing and dyeing wastewater has become one of the most important researches in the field of environmental protection. The membrane bioreactor (MBR), which combines biological treatment and membrane separation, is a new technology for wastewater treatment and reuse, and has a promising application future for the treatment of slow-biodegradable organic wastewater. Its removal effect of the organic contaminants, influence of sludge concentration and flow of aeration, characteristics of the accumulation of organic compounds and the decline and restoring of membrane flux were investigated through treating the wastewater from Tian Xing Printworks in Huiyang District, Huizhou city, Guangdong province in this dissertation. Experimental results showed:When hydraulic retention time (HRT) was 50 hours and the original COD_Cr, BOD₅ and chroma was 506.8mg/L¹275mg/L, 46.1mg/L⁴81.7mg/L and 100multiples⁴00multiples respectively, and the MBR's removal efficiencies were 65%⁸1%, 89.7%⁹9.8% and 50%⁸0%.Sludge concentration decreased from 4.316g/L to 0.868g/L in the testing phase of the experiment. After supplying sludge again, sludge concentration increased and had a stable value of around 5.660g/L due to the effect of hydrolysis.When MLSS was 1.022g/L, 3.812g/L and 5.539g/L, the optimal flow of aeration in the MBR was 0.025m³/h, 0.038m³/h and 0.08m³/h respectively. The fact showed that the flow of aeration increased with MLSS under the optimal conditions.There was a lot of soluble microbial products (SMP) produced in the beginning of operation, and the concentration of organic compounds intercepted by membrane increased rapidly. After reinforcing the effect of hydrolysis, the accumulation of organic compounds obviously lessened. The results showed that reinforcing the effect of hydrolysis helped to improve the biodegradable capability ofSMP.The declining of membrane flux increased with the concentration of sludge. The increasing of aeration amout could slower the course of declining of membrane flux and clearly improve the membrane's filtration capability. Aerating and backwashing helped restoring membrane flux. The sedimentation resistance was the largest of the total fouling resistance(the ratio was 91.2% at the end of the experimentation). Chemical cleaning could thoroughly wipe off the contaminant on the membrane(the flux after cleaning accounted for 99.4% of the original flux).