Study On Organic Wastewater Treatment With Wastewater Land Treatment Technology

The sewage high efficiency naturally purifying technology under plow layer earth is a natural ecological purification technology which uses an ecosystem composed by Soil-Microorganism-Plant to dispose of sewage on the flow through the system, purifying pollutants and improving effluent quality. The pollutant removal mechanism of wastewater land treatment includes adsorption and filtration of the biofilter material inside, absorption of vegetation and decomposition of microorganism. The wastewater land treatment has the following advantages: low construction investment and operating costs, simple management, stable operating, better removal efficiency, great compatibility to loading changing, salient profit of ecological surroundings and society and effluent reusing, etc.The test studies the treatment of organic wastewater by the simulated sewage high efficiency naturally purifying technology. The experiment device consists of two parallel reactor units which are filled with ceramsite and detritus respectively. Adopting the synthetic sewage as influent,the operating parameters are studied which can make the effluent to meet the standard,such as HRT,COD volume loading,adding alkalinity and temperature.Meanwhile,the clean-up effect of different reactor units to organic wastewater is compared. The conclusion is summarized as follow:1. The start-up method of"continuous flow following low concentrate and stationary loading"is adopted in the early experiment.The COD removal rate is tend to be stable on the 15th day under the temperature of 14.2~19.5℃,the design flow rate of 20L/d and the HRT of 144h. It takes about 25 days to succeed in cultivating biofilm. The average of ceramsite unit and detritus unit are 78.4% and 87.9%,the max COD removal rate are 80.02% and 90.66% respectively.The system doesn`t have ability to remove NH4+-N and TP.2. Under the same temperature and influent concentration,more microbial degradation to organic wastewater works with the HRT increasing and COD volume loading decreasing,making the better effluent effect of system.When HRT is 288h and COD volume loading is 0.125kgCOD/(m3 ? d),system has the best operational effect which the COD removal rate of ceramsite and detritus are 83.03% and 82.17% respectively,the BOD5 removal rate are 82.46% and 81.76%.3. The alkalinity factor can affect the system treatment.Under the temperature of 19~23℃,the COD and BOD5 of system effluent didn`t reach the standard of discharging into the city sewers when the alkalinity is not added in the influent,the COD average removal rate of ceramsite and detritus are 27.57% and 32.53% only, the BOD5 average removal rate are 28.99% and 33.53% only;On the other hand,when alkalinity(Na2CO3) is added in the influent whose concentration is 200 mg/L, the COD and BOD5 of system effluent can meet the standard, the COD average removal rate of ceramsite and detritus are up to 76.24% and 72.21%, the BOD5 average removal rate are up to 76.79% and 75.38%.4. The temperature is also an important factor which can effect the unit operation. Under the temperature of 19~23℃, the system works the best and the COD and BOD5 of effluent can reach the standard. The COD average removal rate of ceramsite and detritus units are 78.5% and 75.53% respectively, The BOD5 average removal rate are 77.68 and 77.5%. When the temperature dropped to 4~7℃,neither the COD nor BOD5 of effluent can reach the standard, The COD average removal rate of ceramsite and detritus units dropped to 64% and 51.31% respectively, The BOD5 average removal rate dropped to 62.99% and 51.56% respectively.5. The treatment effect of ceramsite unit to COD and BOD5 is better than detritus unit.The COD average removal rate of ceramsite and units are 71.09% and 64.18% respectively, The BOD5 average removal rate are 70.81% and 65.06% respectively.6. The best operating condition parameters which can make the COD and BOD5 of effluent to reach the requirement of is present as follow:the temperature range is 19~23℃,the HRT is 72h, the alkalinity(Na2CO3)is added in the influent whose concentration is 200 mg/L.7. The biodegradability and water quality`s stability are very important factors which are associated with the system`s decontamination capability.For the readily biodegradable wastewater, the COD average removal rate of ceramsite and units are 89.77% and 82.14% respectively, the BOD5 average removal rate are 89.71% and 82.12%;For the hardly biodegradable wastewater, the COD average removal rate of ceramsite and units are 55.52% and 44.52% respectively, the BOD5 average removal rate are 81.18% and 67.89%.