Study On The Monitor Techniques Of Industrial Toxic Pollutants In The Drainage Nets Of Airport Development Area And Their Effect To The WWTP Normal Operation

With the rapid development of the industries in Three Gorges reservoir area, the influence of the wastewater to the reservoir water environment increases seriously. The composition of industrial wastewater is complex, the concentrations of the pollutants are high and it often has some toxic substances such as acid, alkali, heavy metals, toxic organics ect. At present, only the wastewater which have been pretreated and have met the standards can discharge into the urban drainage networks, but due to the accident and excessive discharge by some industries, the receiving WWTPs in the reservoir always have to face the impact of high proportion industrial wastewater. This made the industrial toxic pollutants in the influent of the WWTPs increased, which could bring bad effects to the biological treatment systems of the WWTPs and damage the normal operation of the plant and even lead the systems to be collapsed. This paper paid attention to the issue of the impact of industrial wastewater from Airport Development Area in ChongQing to the biological treatment systems of the receiving plant called ChengBei WWTP, meanwhile it studied and analysised the characteristics of the water quantity and quality about the main industrial enterprises in the Area. Combines the terrain of the Area, arrangement of the drainage network and distribution of the enterprises, the Area was divided into east and west regions and the location of the industrial toxicity pollutants online monitoring points were determined. Through the analysis of the relevance between the toxic indexes and the water quality of the wastewater from the key industrial enterprises and two online mornitoring points, finally pH and conductivity were determined as online monitoring indexes. Through experiments this paper also studied the influence of the typical low pH and high pH industrial wastewater from the Area to the biological treatment systems of ChengBei WWTP.The water quantity and quality investigation of the main industrial enterprises in the Area showed that, enterprises which are easy to bring alkaline wastewater impact to ChengBei WWTP are GuangDa and ZhongYi, the pH value of their wastewater sometimes can reach up to 9.83 and 12.24. While enterprises which are easy to bring acidic wastewater impact are ZaiSheng,YinXiang and FengHua, the pH value of their wastewater sometimes can decrease as low as 2.01,4.74 and 4.36. Abnormal conductivity always accompanied abnormal high concentration pollutants of the wastewater discharge by the enterprises in the Area. Such as ZhongYi, when COD_Cr and TN of its wastewater reached up to 6885 mg/L and 34.41 mg/L, which were 17.9 and 2.0 times of their average values, the conductivity of this wastewater can reached up to 14500μS/cm which was 11.6 times of its average value. So was DianChi, when the concentration of Zn appeared a peak and reached up to 1.2952 mg/L which was 2.6 times of its average value, the conductivity of this wastewater can reached up to 5480μS/cm which was 2.4 times of the average value. The toxic pollutants in the wastewater discharged by ZhongYi include benzene, lubricants and some refractory organics which are complex and difficulty to be degraded, while the toxics pollutants of ZhongNan include benzene series and some alkanes, ect.The analysis of the toxicity of the wastewater discharged by key enterprises and the monitoring points showed that: the average values of the toxicity indexes which include BOD₅/COD_Cr, SOUR, and the Luminous Intensity of luminous bacteria about the monitoring point in western are 0.37, 20 mgO₂/(g·h) and 37%, while the monitoring points in estern are 0.33,18 mgO₂/(g·h) and 35%. And the toxicity indexes of the monitoring points have good liner relationship to pH and conductivity. Therefore, pH and conductivity were chosen as online monitoring indexes to monitor toxicity pollutants of the industrial wastewater in the Area.The experiment results of the influence about abnormal pH industrial wastewater to the biological treatment systems of ChengBei WWTP showed that: the low-pH wastewater from ZaiSheng had significant effect on the activity, sedimentation and biological properties of the sludge in oxidation ditch of ChengBei WWTP. Compared to the city wastewater which haven't added low pH wastewater from ZaiSheng, when the proportion of low pH wastewater increased to 60%, the OUR value of the sludge would fell 6 mgO₂/(g·h) and the SV₃₀ value increased 9%, the sludge activity began to be significantly affected. When the proportion exceeded 90%, the OUR value of the sludge could decreased to less than 8 mgO₂/(g·h) and the sludge began to be poisoned, the SV₃₀ value increased by 20%, and the microbial would reducted sharply. When the MLVSS was 1.93g/L and the proportion were 100%, the OUR value of the sludge would drop to 3.15 mgO₂/(g·h), this indicated the sludge has been seriously poisoned and has lost activity.The high-pH wastewater from ZhongYi and GuangDa had not significant effect on the activity, sedimentation and biological properties of the sludge in oxidation ditch of ChengBei WWTP. Compared to the city wastewater which haven't added high pH wastewater, when the proportion of high pH wastewater increased to 90%, the OUR value of the mixture which had added wastewater of ZhongYi in had decreased 8 mgO₂/(g·h), SV₃₀ value have increased 7%; while the OUR value of the mixture which had added wastewater of GuangDa in had decreased 12 mgO₂/(g·h), SV₃₀ value have increased 8%, indicated that the activity of the sludge began to severely affected, when the proportion exceeded 90%, the OUR value of the sludge began to acceleratly drop down and the settlement performance became deterioration and the number of the microorganisms in the sludge significantly reduced, indicated that the sludge was seriously affected.