| Recently,large amounts of wastewater were produced every year throughout the country and the volume is still increasing,which imposes great challenges on pollution control and water resource protection.In some region,industrial wastewater is not isolated from domestic wastewater,which puts forward higher requirements for the wastewater treatment plant.This project focused on upgradation and reconstruction of Taizhou Huangyan Jiangkou WWTP targeting at treatment of mixture of industrial wastewater and domestic wastewater.The technical proposal was established by specific experimental results.Technological design was done according to the above results.After upgradation,the effluent reached the local standards（higher than the national standard,level I-A）.According to the upgradation requirement,the current operation situation of Jiangkou WWTP was investigated first.Detailed analysis of water quality including general parameters and heavy metals was conducted on the mixture of municipal wastewater and industrial wastewater after entering the WWTP,industrial wastewater,industrial wastewaters from different industry zones and municipal wastewater.The obtained results showed that the main reasons that affected the effluent quality from this WWTP were excessive discharge of pollutants in industrial wastewater,high concentrations of recalcitrant pollutants,and inhibition of nitrification by heavy metal ions.On this basis,the solution of"incorporate pretreatment for industrial wastewater,reforming current oxidation ditch and incorporate deep treatment module"was determined.Experiments on pretreatment of industrial wastewater,MBBR（Moving Bed Biofilm Reactor）and high efficiency sedimentation tank were carried out in field test.In the pretreatment test of industrial wastewater,after 30 min’s static sedimentation,SS was reduced by 60%～90%,COD and TP could be removed simultaneously.In the MBBR process,the biofilm was formed in a good condition.When the flow rate of influent was stabilized below 1.3 m3/h with NH4+-N concentration in the range of 15～50 mg/L,the NH4+-N in the effluent was below 7mg/L.When the system is impacted by water quality and quantity in a short period of time,the symbiotic system of sludge flocs and biofilm could recover to the normal state quickly.In the deep treatment module,traditional coagulation and precipitation process had a good performance on removal of COD,TP and SS,with 20%～30%and 80%～90%of COD and TP were removed from the secondary sedimentation tank effluent,respectively.Adding powder activated carbon displayed a perfect performance on COD removal;The dosage of flocculant（10%Al2O3 solution）was 10～15 mg/L（active ingredient）.According to the experimental results and the discharge standards,the upgradation and reconstruction proposal was determined as follows:heavily polluted industrial wastewater:fine grille+grit chamber+regulating tank+coagulation and precipitation+hydrolysis and acidification process;Main process for sewage treatment:MBBR process+activated carbon high-efficiency sedimentation tank+V-type filter tank+disinfection.After the proposed upgradation,Jiangkou WWTP worked well in wastewater treatment.The field test achieved expected operation effects and the designed discharging standard.Under the standard operation condition,the effluent water quality stably met the discharging standard.The direct construction cost of this project was RMB 253.33 million yuan.The operation cost（electricity,water,chemicals,etc.）was about RMB 0.89 yuan/m3 wastewater;Powder activated carbon and carbon source agents could be added according to the water quality. |
