填料碳种类对蚯蚓生物工程床净化畜禽养殖污水的影响

蚯蚓对不同种类填料碳的分解转化特征各异,继而影响蚯蚓生物工程床净化养殖污水的效果。为明确填料碳种类对净化畜禽养殖污水的影响特征,以水稻秸秆和水稻秸秆生物炭为生物工程床碳源填料,采用间隙式布料方式,连续22 d监测进水和出水水质。结果表明:秸秆填料的生物工程床对畜禽养殖污水特征污染物平均削减量分别为硝态氮67.2%,氨氮81.4%,总氮79.5%,磷酸盐29.9%,总磷35.2%,COD 21.4%,EC值77.8%;秸秆填料的生物工程床中添加蚯蚓后改变了特征污染物削减量,提升平均削减量分别为氨氮11.1%、总氮10.4%、磷酸盐17.8%、总磷73.9%和COD 27.3%,降低平均削减量分别为硝态氮10.3%和EC值3.4%;生物炭填料的生物工程床对畜禽养殖污水特征污染物平均削减量分别为硝态氮36.8%,氨氮86.2%,总氮53.4%,磷酸盐21.2%,总磷33.3%,COD 33.3%和EC值51.7%;生物碳填料的生物工程床添加蚯蚓后改变特征污染物削减量,削减量平均提升分别为硝态氮0.4%、氨氮1.4%、总氮10.6%、磷酸盐26.0%、总磷29.5%、COD 39.2%和EC值0.7%。秸秆填料和生物炭填料的生物工程床对出水p H值增加量平均为3.1%和7.7%,添加蚯蚓后出水p H值下降,平均下降率为0.1%和7.7%。总之,填料碳种类和蚯蚓活动显著影响生物工程床净化养殖污水的效果,秸秆填料有利于畜禽养殖污水硝态氮、总氮、磷酸盐、总磷和EC值削减;生物炭填料有利于畜禽养殖污水氨氮和COD削减,并显著增加出水p H值。生物工程床添加蚯蚓后明显提高畜禽养殖污水氨氮、总氮、磷酸盐、总磷和COD的削减,但不利于硝态氮削减。

Effects of different types of carbon based filter materials on purification of livestock wastewater by earthworm bioengineering bed

Earthworm is a soil residence animal, which can effectively enrich and remove nutrients in the environment, and its role in the field of ecological environment has gained more and more attention.Earthworm bioengineering bed can efficiently purify various sewages. In such bioengineering, the filter is an important part, and carbon material is the core material of the filler.In order to determine the impact of the carbon types on the earthworm bioengineering bed, in this study, rice straw and biochar were used as carbon source filler, and livestock wastewater was added to the bioengineering bed at different time interval.The inlet and outlet water quality parameters were continuously monitored for 22 d.Results showed that bioengineering bed of rice straw as filler could significantly reduce various pollutants in livestock wastewater.The pollutant reduction was 67.2% of nitrate nitrogen, 81.4% of ammonium nitrogen, 79.5% of total nitrogen, 29.9% of phosphate, 35.2% of total phosphorus, 21.4% of COD (chemical oxygen demand) and 77.8% of EC (electric conductivity) value.The bioengineering bed of rice straw filler changed the pollutant reduction in the addition of earthworms.The increase of average reduction was 11.1% of ammonium nitrogen, 10.4% of total nitrogen, 17.8% of phosphate, 73.9% of total phosphorus and 27.3% of COD, and the average reduction was 10.3% of nitrate nitrogen and 3.4% of EC value.Bioengineering bed of biochar as filler could significantly reduce various pollutants in livestock wastewater, and pollutant reduction was 36.8 % of nitrate nitrogen, 86.2% of ammonium nitrogen, 53.4% of total nitrogen, 21.2% of phosphate, 33.3% of total phosphorus, 33.3% of COD and 51.7% of EC value.The bioengineering bed of biochar filler increased the pollutant reduction in the addition of earthworms, and the increase of average reduction was 0.4% of nitrate nitrogen, 1.4% of ammonium nitrogen, 10.6% of total nitrogen, 26.0% of phosphate, 29.5% of total phosphorus, 39.2% of COD and 0.7% of EC value.After bioengineering bed treatment, average increase of pH value of outlet water was 3.1% for rice straw as filler, and 7.7% for biochar as filler.The average decline rate of pH value of the outlet water in adding earthworms was 0.1% and 7.7%.In summary, the type of carbon and earthworm activity significantly influenced the effect of livestock wastewater purification for the earthworm bioengineering bed.The straw filler was beneficial to the reduction of nitrate nitrogen, total nitrogen, phosphate, total phosphorus and EC of the livestock wastewater.Biochar filler was conducive to the reduction of ammonium nitrogen and COD in livestock wastewater, and significantly increased the pH of outlet water.The removal rate of ammonium nitrogen, total nitrogen, phosphate, total phosphorus and COD was significantly improved after adding earthworm into bioengineering bed, but it was not conducive to the removal of nitrate nitrogen.It was the most conducive to the removal of pollutants in livestock wastewater that adding earthworm into the bioengineering bed filler which was made by the biochar and straw in a certain proportion.