Abstract:
Various advanced technologies have been utilized to treat the livestock and poultry manure, and wastewater in the breeding industry in recent years. This study aims to better track the progress of the treatment and utilization of manure and wastewater. A nationwide survey was conducted from 2018 to 2020, covering 3 162 pig, cattle, and poultry farms. The technical pathway and facility construction were fully analyzed from the aspects of the collecting approaches, treatment technologies, and utilization of the farmland. The results show that the dry-dung cleaning was the main way for the manure and wastewater collection in most surveyed farms (89.40%), while the water flushing and deep-pit were frequently adopted in 6.27% and 2.70% of surveyed pig farms. Composting has been widely used for the treatment of solid feces, accounting for 89.44% among surveyed farms. 80.35% of the composting facilities cannot meet the requirement for manure maturity. Besides, the manure maturity depended mainly on the raw material and fermentation in the composting application. Anaerobic fermentation and storage technologies were mainly used in the treatment of wastewater. About 40% of the anaerobic fermentation tanks cannot meet the capacity requirements. Furthermore, the period of storage time should be longer than 6 months to kill all pathogens in storage treatment, but only 31.30% of surveyed farms met the requirement. 21.4% of surveyed farms that adopt the ectopic fermentation beds did not met the standard capacity requirements. Most treated manure and wastewater were used for the fertilizers for the farmland with fruits and vegetables, while the application to the farmland with grain crops was still low. The average dosages of land application of manure and wastewater were 48.3 and 130.5 t/hm2, respectively. The overall dosage using nitrogen demand was relatively higher than that of plant need, leading to water pollution. Meanwhile, manual fertilization was still the major treatment, compared with mechanical fertilization. A prediction was also made on the development trend of technology application of livestock and poultry manure. The guiding concept was shifted from pollution prevention to resource utilization from the perspective of the selection of technology for treatment and disposal. Some approaches were widely used in small and medium-sized breeding farms, such as compost, storage, and anaerobic fermentation for the nearby land application. But the selection of technical modes was still not very effective in some places, leading to some problems, such as high cost, low odor control, and harmless effect. Most of the farms were basically equipped with manure treatment and utilization facilities, particularly for the functions of seepage, rain, and overflow prevention. But some of the facilities cannot match the scale of breeding. The construction and operation of the facilities cannot be standardized on parts of farms. Mechanized fertilization was improved, in terms of manure returning to the field. But the general lacking was the tracking and monitoring of land for the risk of environmental pollution with excessive application of manure. Some recommendations were proposed to improve the treatment and utilization of livestock and poultry manure, and wastewater. The national standardization was considered for the construction of treatment facilities and farmland application, thereby developing the appropriate machinery for organic fertilizer application to farmland. The large-scale livestock and poultry farms can be guided to match the adequate farmland, according to the yields of manure and wastewater.