| To better apply the self-adaptive micro-tubule dynamic membrane module as commercial productions, in the present study, the operation characteristics of the membrane module for the textile wastewater treatment were examined. Moreover, the characteristics were compared with the operation characteristics of the membrane module using for the municipal wastewater treatment. The screening of the key parameters for flux enhancement were conducted. The long-term application and actual effect of the self-forming dynamic membrane bioreactor were investigated to evaluate the performance of dynamic membrane. The main studies and conclusions are as follows:The comparison among operation characteristics of the textile wastewater treatment and the municipal wastewater treatment were investigated. At the same head loss, when compared with operation characteristics of municipal wastewater treatment, we found:Considering the operation conditions and treatment efficiency, the flux of the dynamic membrane for textile wastewater treatment dropped rapidly right after the running started, and the membrane had the shorter stable operation time, smaller pores, and blocked easily. However, it has the similar processing efficiency as using in the municipal wastewater treatment. Considering the sludge characteristics and the membrane structures, the textile wastewater treatment led to finer sludge, slower settling, smaller membrane pores, lower membrane flux and easier blocks.The different operating characteristics of head losses and cross-flow velocity were explored and the critical flux of different initial fluxes and sludge concentrations were examined. The higher of the head loss, flux declined faster, the stable operation time was shorter. When the initial flux was within the range of 430L/(m2·h)～600L/(m2·h), dynamic membrane could form quickly within 8 min. Under this formation condition, the dynamic membrane critical flux was 65L/(m2·h)～70L/(m2·h). When the membrane’s initial flux went up, critical flux of dynamic membrane declined. When the concentration of sludge increased, dynamic membrane critical flux decreased, under the concentration of sludge was 3000mg/L～5000mg/L, the critical flux was 65L/(m2·h)～70L/(m2·h).The operation characteristics of four kinds of sub critical flux (15L/(m2·h)、 30L/(m2·h)、45L/(m2·h)、60L/(m2·h)) of dynamic membrane were examined. In the four sub critical fluxes, the pollutant removal of dynamic membrane was not significantly different (p>0.05). Dynamic membrane could contribute to the removal of UV254、COD and NH3-N by itself. And it had no effect on the removal of TP. Under the critical flux of 60L/(m2·h), the highest removal was observed by the membrane itself. The change trends of membrane resistance were similar. However, the membrane resistance showed big differences until the late in operation, which was mainly attributed to the fouling distribution of dynamic membrane modules pores, but not caused by the fouling inside the membrane module.The characteristics of long-term operation under the external dynamic membrane module were studied and the operating parameters were determined. External components run continuously for 30 cycles, and total operation time reached 456h.The longest single cycle was up to 72h, which showed good flux recovery and pollutant removal. The average concentrations of the color, COD and NH3-N in the effluence were 93.2%、3.61%、94.0% respectively. The optimized operation mode was as follows: the operation cycle time was 20 hours and the backwash method was "wash the outside and impulse wash the inside of the membrane tubes". Compared with the wastewater treatment system of the commercial textile factory, the miniature animal community structure of the activated sludge in DMBR was relatively poor, but the DMBR effluent quality was slightly better, turbidity and SS had obvious advantages especially.This study is able to guide engineering design and operation management of the self-adaptive micro-tubule dynamic membrane module using for textile wastewater treatment. |
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