Study On Swine Wastewater Treatment By Iron Carbon Microelectrolysis-Physical Absorption-Microalgae Combined

The piggery wastewater discharge is large,and the suspended matter content and organic matter content are high,also the nitrogen and phosphorus content are large.If this kind of wastewater with high concentration of pollutants is discharged without treatment,it will cause serious air,soil,water and other pollution problems.In view of the problem of wastewater pollution caused by swine breeding,the existing single wastewater treatment methods have their own advantages and disadvantages:the physical adsorption process is simple and easy to operate,but it cannot handle high concentration organic wastewater;iron carbon microelectrolysis has a good decolorization effect on wastewater,which can improve the biodegradability of wastewater,but the effluent still does not meet the prescribed discharge standards,and in case it cannot be returned to the field,further processing is required;the microalgae treatment of wastewater is environmentally friendly,and at the same time it can harvest biomass energy,but the wastewater needs to be pretreated to cultivate microalgae.There can be seen that there is a deficiency in the single treatment process,and it is difficult to achieve a good treatment effect.The combined process combines the advantages of various single treatment methods to more effectively solve the problem of difficult treatment of high concentration organic aquaculture wastewater.This test combined iron carbon microelectrolysis,physical adsorption and microalgae processes to treat piggery wastewater.Firstly,the process conditions were determined by single factor test on different pH values,reaction time and iron carbon dosage of iron carbon microelectrolysis.Secondly,the piggery wastewater treated by iron carbon microelectrolysis was subjected to adsorption test to analyze the effect of the removal of pollutants by zeolite and vermiculite in different dosages and reaction time,especially the removal effect of ammonia nitrogen,and then determined the process conditions.Finally,the piggery wastewater treated by iron carbon microelectrolysis?IM group?,the piggery wastewater treated by iron carbon microelectrolysis+zeolite?IZM group?,the piggery wastewater treated by iron carbon microelectrolysis+vermiculite?IVM group?and BG11 medium?BG11 group?cultured Chlorella for 16 days,and then analyzed the pollutant removal effect of wastewater,growth and lipid productivity of Chlorella,and evaluated the iron carbon microelectrolysis-physical adsorption-microalgae combination process,and it can provide a theoretical basis for the treatment of pig wastewater by this process in the future.The main results of the test were as follows:1.The test of different influent pH,reaction time and filler dosage of iron carbon microelectrolysis showed that the influent pH was 3,the reaction time was 150 min,and the iron carbon dosage was 200 g·L^-11 could achieve better processing results.2.The piggery wastewater treated with iron carbon microelectrolysis was further treated with zeolite and vermiculite.The test results show that that the process parameters were better when the dosage of zeolite and vermiculite were 350 g·L^-11 and the adsorption time were 5 h.3.In this test,the COD,total phosphorus?TP?,total nitrogen?TN?and ammonia nitrogen?NH₄⁺-N?contents of the piggery wastewater were 1880.00±42.06 mg·L^-1,48.29±1.03 mg·L^-1,103.79±0.59 mg·L^-11 and 56.73±0.36 mg·L^-1,respectively.The highest removal rates of COD in piggery wastewater by iron carbon microelectrolysis+microalgae?IM?combined process,iron carbon microelectrolysis+zeolite adsorption+microalgae?IZM?combined process and iron carbon microelectrolysis+vermiculite adsorption+microalgae?IVM?combined process were 94.41%,94.13%and 93.79%,respectively,and the effluent quality reached the COD secondary emission standard in the National Integrated Wastewater Discharge Standard?GB8978-1996?.The maximum removal rate of TP in piggery wastewater by IM combined process,IZM combined process and IVM combined process were 99.71%,and the effluent quality reached the TP first-level emission standard in the National Integrated Wastewater Discharge Standard?GB8978-1996?.The highest removal rates of TN in piggery wastewater by IM combined process,IZM combined process and IVM combined process were 52.37%,51.66%and57.93%,respectively.The highest removal rates of NH₄⁺-N in piggery wastewater by IM combined process,IZM combined process and IVM combined process were 93.97%,94.15%and 98.34%,respectively,and the effluent quality reached the national first-level discharge of NH₄⁺-N in the National Integrated Wastewater Discharge Standard?GB8978-1996?.4.Chlorella could grow in piggery wastewaters treated by three different processes.During the culture period,the biomass of the BG11 group showed an upward trend,while the biomass of the IM group,the IZM group and the IVM group began to decline at different times.The initial N content of IZM group and IVM group were lower than that of IM group.In the later stage of culture,the biomass indexes of IZM group and IVM group were significantly lower than those of IM group?p<0.05?.It indicated that the lack of N element in wastewater would inhibit the growth of Chlorella.5.The lipid productivity?LP?of Chlorella from the three different treatment processes from high to low were:IZM group?34.82%?,IM group?31.52%?and IVM group?31.45%?.The difference in LP among the three groups was not significant?p>0.05?,but the LP of the three groups were significantly higher than that of the BG11group?22.74%??p<0.05?.Chlorella has gained more lipid in the IM combined process,the IZM combined process and the IVM combined process.