蚯蚓堆肥模式的环境效益评价

Environmental benefits evaluation of vermicomposting

蚯蚓堆肥是废弃物资源化利用的有效途径,为明确规模化蚯蚓处理废弃物过程中碳(C)、氮(N)、磷(P)元素的物质变化规律与环境效益,以工厂化蚯蚓处理牛粪模式为对象,分析各环节物料的属性变化、气体排放规律和养分向堆体下方土壤迁移情况,并量化环境影响值。研究结果显示,蚯蚓处理过程中,固体物料全C、C/N和C/P均表现出降低的趋势,全N含量有所提高,pH和全P无明显变化;蚯蚓粪成品C/N、NH_(4)^(+)和NH_(4)^(+)/NO_(3)^(-)的范围均达到堆肥腐熟的标准。随着蚯蚓堆肥过程的进行,CH_(4)和N_(2)O的排放速率呈降低的趋势,CO_(2)和NH_(3)分别在蚯蚓处理中期和初期排放达到最高;C、N通过气体形式损失率分别为25.2%和10.9%。堆放牛粪后,土壤全N和全P含量主要在0~20 cm深度有所增加,平均增幅分别为23.8%和12.0%;NH_(4)^(+)和NO_(3)^(-)含量在不同土层均有所提高;有效P含量在0~10 cm深度增幅达到3倍以上。蚯蚓处理牛粪的全球变暖潜势、富营养化潜势、酸化潜势分别为181.1 kg CO_(2) eq/t、0.24 kg PO_(4) eq/t和1.29 kg SO_(2) eq/t,整体优于传统的好氧堆肥和厌氧发酵模式。研究结果可为蚯蚓处理过程中的品质控制、气体减排和污染防控提供理论参考,并为蚯蚓堆肥处理废弃物模式的工厂化应用推广提供思路。

Vermicomposting is an effective way in resource recycling.This study focused on the investigation of the changes in carbon(C),nitrogen(N)and phosphorus(P)and the evaluation of the environmental benefits during vermicomposting.Taking the industrial vermicomposting of cow dung for research objects,the characteristics of substrates,the gas emissions,and the nutrient transfer to soil were studied.The results showed that the total C,C/N and C/P of substrates presented a decrease trend,the total N content presented an increase trend,the pH and total P had no significant change during vermicomposting.The final values of C/N,NH_(4)^(+)and NH_(4)^(+)/NO_(3)^(-)all reached the standard of compost maturity.The greenhouse gas of CH_(4) and N_(2)O emission showed a reducing trend.However,the emission peak of CO_(2) and NH_(3) were at the middle and early stage during vermicomposting,respectively.At the final stage,the loss rate of gaseous C and N were 25.2%and 10.9%,respectively.Under the substrates,soil total N and total P content increased by 23.8%and 12.0%at 0~20 cm depth,respectively.The soil NH_(4)^(+)and NO_(3)^(-)content were all increased to different extents at 0~40 cm depth,and the available P increased over triple at 0~10 cm depth.The global warming potential,eutrophication potential,and acidification potential of vermicomposting were 181.1 kg CO_(2) eq/t,0.24 kg PO_(4) eq/t and 1.29 kg SO_(2) eq/t,respectively.The environmental benefits of vermicomposting were generally better than conventional aerobic composting and anaerobic fermentation.These results provided theory and data support for quality control,gas reduction and pollution prevention during vermicomposting,and provided guidelines to popularize the mode of vermicomposting of cow dung.