Decontamination Of Primary Piggery Wastewater Coupling With Lipid Production Based On Chlorella Cultivation

This research used the primary piggery wastewater by cultivating Chlorella,withprompting algae cell growth and oil accumulation.This method provided a kind ofway of the realization of waste water recycling and an conomic way of producingbiolipids.Main contents of the present study are listed as below.Lipids in Chlorella sp. was extracted directly with chloroform-methanol, orextracted with that after grinding or ultrasonic treatment in the present study.Compared with the method of Soxhlet extraction by ether-petroleum solvent, theoptimized ultrasonic extracting method had a much higher extraction rate. Moreover,the convenience in proceeding and the short duration of production provide a basis forextracting biological oil quickly and efficiently.The primary piggery wastewater was obtained through filtered by gauze andhollow fiber membrane and flocculated by flocculating agents. Chlorella pyrenoidosawas cultivated with the three type of wastewater medium. The result showed that theC. pyrenoidosa could grow normally in the primary piggery wastewater filteredthrough hollow fiber membrane and flocculated with chitosan. C. pyrenoidosa grewbetter in the primary piggery wastewater after flocculated with chitosan, in which thecell dry weight and the lipid content were0.567g/L and20.53%respectively. Thefatty acid composition of C. pyrenoidosa varied with the different processing methodof piggery wastewater. In the mean time, C. pyrenoidosa removed the total nitrogen,total phosphorus, ammonia nitrogen and COD(chemical oxygen demand) duringgrowth process in the piggery wastewater.The removal rate of total nitrogen, totalphosphorus, ammonia nitrogen and COD was68.42%,70.35%,83.48%and63.60%,respectively, which showed that the piggery wastewater could be decontaminated byC. pyrenoidosa.The piggery wastewater was disinfected with ozone (O3) to overcome unstablegrowth of C. pyrenoidosa caused by complex microflora of medium. Sterilization rateof97.0%was arrived when the O3residual concentration was2.87mg/L. The growthof C. pyrenoidosa and the water quality were not been influenced by the ozoneaeration. The growth of C. pyrenoidosa grew well and stable cultivated in the initial1000mg/L COD piggery wastewater treated by ozone (O3), which the biomass andlipid content were1.11g/L and22.27%respectively. Meanwhile the removal rate oftotal nitrogen, total phosphorus, ammonia nitrogen and COD was higher and reached85.29%、81.26%、93.82%and74.00%respectively. The continuous access of pure air, continuous access of5%CO2mixed with airand the pure CO2access of constant pH control were coupled with the process ofcultivating the C. pyrenoidosa with primary piggery wastewater.The results showedthat the growth and the polyunsaturate fatty acid of the C. pyrenoidosa increased withthe access of CO2.The growth of C. pyrenoidosa was optimal with the way ofcontinuous access of5%CO2mixed with air, which the biomass and lipid contentwas1.84g/L and28.87%respectively. The removal rate of total nitrogen, totalphosphorus, ammonia nitrogen and COD respectively was85.29%,81.26%,93.82%and74.00%. The cultivate model of microalgae biomass was established thatcombined with CO2conversion and decontamination of the primary piggerywastewater.