Modeling the contribution of pig farming to pollution of the Thachin River

Rapid growth of the livestock production sector in South-East Asia during recent decades has led to a widespread degradation of ground and surface waters. The Thachin River Basin in Central Thailand serves as a case study for investigating the origins and pathways of nutrient loads produced by intensive pig farming. A mathematical material flow analysis is used to identify key nitrogen flows and the main parameters determining them. Scenarios of the potential for reducing these flows and achieving compliance with current discharge regulations are investigated. The results show that liquid waste discharged from large pig farms and directly discharged waste from small farms are the key nitrogen flows to the river system. The key driving forces are not only the treatment coverage and efficiencies but also the rate of reuse and recycling of the treated product.