Study On Efficiency Of Hydrolytic Acidification And Modified Nitrogen Removal Process For Electroplating Tail Wastewater Treatment

Electroplating industry consumes large water with serious pollution. The quality ofelectroplating wastewater is various because of the different production technologies. Themain pollutions include heavy metal, acid and alkali, ammonia, organic and so on. Thepollutants will pollute the environment if they are not removed efficiently. Presently, theremoval methods of these pollutants include physical treatment, chemical treatment,physical and chemistry treatment, biological treatment and so on. At this stage, heavymetal, acid and alkali can be removed by chemical method, but the removal of CODCrand nitrogen is not efficient. Based on the biological nitrogen removal method has thecharacteristics of simple process, low cost, easy maintenance and so on compared withother methods, biological nitrogen removal method was used to remove these pollutants.The process consists of hydrolysis acidification reactor and improved A/O reactor. TheA/O reactor is improved by adding fillers and revising the way of liquid recycling. Weinvestigate the removal efficiency of the improved process for electroplating tailwastewater treatment. This experiment uses domestic wastewater as part of the carbonsource to treat the mixture of electroplating tail wastewater and domestic sewage. Themain results are as follows:1． Hydrolysis acidification reactor has good performance on improving thebiodegradable ability. When the ratio of electroplating tail wastewater in mixedwastewater is25%, the acidification rate reaches a maximum value of58%and theremoval rate of SS reaches as high as90%with the hydrolysis acidification HRT of6hours.2．The start-up of the process goes through65days in two stages. The removalperformance of the process is stable at the first stage. The average concentrations ofeffluent CODCr, ammonia nitrogen and total nitrogen are65.5mg/L,5.2mg/L and6.2mg/L, respectively, corresponding with the average removal efficiencies of75%,82%and86%at the end of the first stage. The removal performance of the process is stable atthe second stage. The average concentrations of effluent CODCr, ammonia nitrogen andtotal nitrogen are50mg/L,0.5mg/L and12.7mg/L, respectively, corresponding with theaverage removal efficiencies of80%,92%and80%at the second stage.3．The removal efficiencies are varied with different proportion of electroplating tailwastewater. The removal efficiency is increased with the enhancement of biodegradable ability by adding domestic sewage into electroplating tail wastewater. In comprehensiveconsideration of economic benefits and operation effect, it is recommended that the ratioof electroplating tail wastewater and domestic wastewater is1:3. When the proportion ofelectroplating tail wastewater to domestic sewage is1：3with HRT of24h, the removalefficiencies of CODCr, NH4+-N and TN are83%,98%and80%, respectively.4．The sludge concentration can be increased by adding the volcano rock andcombined filler into the system, preventing the loss of sludge. Thus the removalefficiencies of the organic and ammonia in electroplating tail wastewater can besignificantly enhanced.