Study On The Treatment Of Washing Water System

Washing wastewater contained surface active agent, sodium tripolyphosphate, carboxy armour gil element, oil, dust particles and all kinds of microbes and so on. Washing water was large quantity of emission, the number of washings, the high contamination, and many kinds of detergent, which had become a significant source of water pollution. However, present treatment of washing water had the disadvantages of low removal efficiency, the quality indexes of effluent was not up to the standard, high investment and operating cost and so on. The experiment water was from Dalian professional laundry company. Design and study washing water process. Two different craft were designed:coagulation flotation-biological contact oxidation-activated carbon adsorption system, co-coagulation flotation-electro-flocculation system. The results showed that the shock resistance is strong, the adaptive ability was high, the operation was simple, daily operation cost was reasonable, the system running was stable and the effluent is up to standard.The experiments was discussed the different factors influencing coagulation flotation-biological contact oxidation-active carbon adsorption system and co-coagulation flotation-electro-flocculation system. The results revealed that:In the co-coagulation flotation experiment, the removal rate of COD for PAC was best in different coagulants. In the best test conditions, PAC was200mg/L, PAM was5mg/L, pH was7, optimum reflux ratio was50%and HRT was20min. The removal efficiencies of COD NH4+-N TP and SS were around65%40%35%and85%respectively.In the biological contact oxidation process, sewage came from co-coagulation flotation. COD was350～400mg/L, NH4+-N was30-35mg/L, TP was7.5-8mg/L. In the following experimental conditions:pH value was between7and8, aeration rate was0.04m3/h and hydraulic retention was time7.0h. The removal rate of COD was above90%, the ammonia nitrogen removal rate was above60%, the TP removal rate was above50%. The system was strong impact resistance ability.The large specific area of activated carbon is capable of adsorbing the pollutants in wastewater. The flow purified in biological contact oxidation was treated by activated carbon. The result shows that COD removal efficiency is best by powdery carbon adsorption compared with other adsorbents. The best feeding quantity was2500kg/m3and the best contact adsorption time was40min. The COD NH4+-N TP and SS of the effluent adsorbed by active carbon were less than lOmg/L4mg/L lmg/L and3mg/L. The effluent reached national level of emissions standards.In the experiment, using electrocoagulation-flotation treatment to remove the pollutants in washing wastewater. The wastewater was out from coagulation-flotation. Test determined the optimal parameters:pH was7, current density was1.50mA/cm2, plate distance was10mm, time was25min. Under the optical conditions the COD and SS removal efficiencies reached up to90%. The NH4+-N and TP of effluent removal rates were above85%. The COD NH4+-N TP and SS of the effluent were35mg/L4mg/L1mg/L and4mg/L. The effluent meet national level standards.