The current practice of livestock wastewater treatment is to separate the waste by solids and liquids, followed by anaerobic or facultative fermentation and aerobic treatment before it's discharged into rivers and irrigation canals. The approach, however, cannot remove nitrogen and phosphorus from the excrement and wastewater. Thus, the rivers are depleted of oxygen and left with a smell. Unfortunately, in order to cut down the cost on wastewater treatment or facility maintenance, some husbandry business owners might choose not to repair malfunctioned facilities or not to use the facilities and bypass the usual outfall to discharge the wastewater into the rivers instead, causing river pollution. Livestock excrement is rich with nitrogen and phosphorus. If it is discharged into rivers instead of being properly utilized, the resources are misplaced.
Given the situation, the Ministry of Environment (MOENV) has set the goal to address the river pollution issues, enhance rural air quality as well as implement the policy of circular economy to recycle livestock excrement and make it into nitrogen fertilizer. Instead of treating excrement as waste which the MOENV used to control and monitor intensively, the MOENV referred to best practices of other countries and started to promote the strategies of "transforming livestock excrement into resources." After the excrement is processed with anaerobic fermentation, the liquor and fiber digestate can be used as nitrogen fertilizers on the farmland. As a result, farmers will be able to cut down the use of chemical fertilizers, while livestock breeders don't need to bear the electricity expense on aerobic treatment (the third step) and save some on the water pollution control fee. Water bodies will be cleaner because less polluted water is discharged. Methane can be collected and used for electricity generation or other purposes. This will facilitate the promotion of circular economy and bring benefits to every party involved.
- Ministry of Environment