Construction and application of comprehensive evaluation index system for waste treatment on intensive livestock farms

Livestock breeding industry is rising rapidly, due to the increasing consumption demand for livestock products, as the improvement of the living standard of Chinese residents in recent years. There is a trend towards intensive, large-scale and professional cultivation in the livestock and poultry sectors, based on both practical experience from other countries, and the guidance of the Chinese government. Consequently, an increasing trend can also be found in the discharge amount of livestock manure, containing most nutrients while harmful ingredients. If these livestock manures were not treated timely, the environment would be polluted seriously, which would also in turn prevent the development of livestock breeding industry. As such, the livestock production has become "one of the three most significant contributors to today's most serious environmental problems". Intensive livestock cultivation has also posed a great challenge on natural ecological system. In this study, taking the manure treatment in intensive livestock farms as the research object, an evaluation index system was established by considering the regional differences, in order to evaluate comprehensive benefit of technical modes for the waste treatment in the current large-scale livestock and poultry manure. An Analytic Hierarchy Process (AHP) method was used to construct the comprehensive evaluation index system, based on the whole production chain, including planning layout, manure collection-storage-transportation, efficient treatment, transformation, and utilization to farmland. Three aspects of the index system can be divided into the technical, economic and environmental indicators, including three first-level index, six second-level index, and 15 third-level index. An expert scoring method was used to determine the weight of each index. Six types of modes for fecal sewage treatment technology were selected to verify the index system in three dominant areas of cow breeding. An example of field experiment was taken as a large-scale dairy farm in Hebei Province. The results showed that: the evaluation method can accurately assess the comprehensive benefits of livestock manure treatment in large-scale farms, covering a practical guidance and good operability. Specifically, the pre-separation composting mode and pre-separation bedding mode were recommended in Northeast China, whereas, the composting mode and pre-separation composting mode were recommended in Northwest China, and the fermentation mode was recommended in North China. It infers that the solid-liquid separation can have a significant impact on the treatment effect in different stages of manure treatment. In Northeast and Northwest China, the performance of pre-separation mode was better than that of the former separation. There was no significant difference in the post-separation mode in North China. The scores of environmental and technical indicators ranked higher at the waste treatment level for the large-scale dairy farm in Hebei Province, indicating a good performance of mode. Some suggestions were also proposed based on the existing conditions in the economic indicators. A case analysis further verified the practical guidance, operability and rationality of the index system. Therefore, this finding can provide a methodology system and theoretical support for the construction of fecal sewage treatment, as well as a sound important reference for the comprehensive benefit evaluation in the waste treatment of intensive livestock farms in the future.