Evaluation of water pollution caused by different pig-farming systems in hungyen province of Vietnam

Abstract

In recent years, pig breeding has developed very fast in Hungyen Province, located in the Red River Delta of Vietnam adjacent to the capital of Hanoi. The following four pig-farming systems are performed there: 1) VAC system: a combination of fruit cultivation, fish culture with pig farming; 2) AC system: a combination of fish culture with pig farming; 3) VC system: a combination of fruit cultivation with pig farming; and 4) C system: only pig farming, respectively. Among these systems, VAC system had the highest occupancy (45.6%), followed by AC system (23.3%) and then by C system (21.5%), and VC system had the lowest occupancy (9.6%) in number in the investigated two districts of the province. The level of the pollution of the surface and groundwater was monitored for the four systems. The monitoring was done six times with a two-month interval during February to December in 2010. As the result, the surface water was evaluated to be strongly polluted in each pig-farming system, i.e. the chemical oxygen demand (COD), biological oxygen demand (BOD), and ammonium-N and phosphate-P concentrations on average exceeded the national technical regulation standard, and the dissolved oxygen (DO) on average was very low. For the groundwater, the average ammonium-N concentration exceeded the standard in each pig-farming system. However, the level of the surface and groundwater pollution was not similar among the pig-farming systems. In general, the level of surface and groundwater pollution was high in C and VC systems, intermediate in VAC system and low in AC system, respectively.