Developing zero-discharge pig-farming system: a feasibility study in Malaysia

Abstract

Pig production in many rapidly developing Asian countries evolved from traditional small-family farms without parallel increase in land resource for waste treatment, thus further worsening the already fragile environment. The present paper reports results of a feasibility study on developing a zero-waste discharge pig-farming system in the hot-humid environment such as Malaysia. The approach included (1) reduction in the usage of water, (2) use of micro-algal culture (MAC) system to reduce pollutants in the wastewater and (3) use of constructed wetlands to further clean up wastewater and reduce its volume via evapo-transpiration. Results of the study showed that water usage could be reduced from the current 40–50 to 7.5 L/pig.day. The biological oxygen demand of the effluent was reduced to below 10 mg/L, while other pollutants, such as suspended solid, total nitrogen and total ammonium nitrogen were also reduced to levels that meet the standards required for affluent discharge in most countries in this region. Water-balance study based on a 180-pig experiment showed that 1.15 m³ of water were used daily and this was reduced to 0.38 m³ at the end of the system. Financial projection study based on a farm size of 2000 pigs (which represents a typical pig-farm size in many developing countries, including Malaysia) was conducted to gauge the economical viability of the system. The results showed that the primary challenge to the adoption of this system is its high initial investment costs, estimated to be 1.8 times those for a similar-sized traditional farm with open-sided house and lagoons for wastewater treatment. However, higher productivity is expected from the use of a ventilated close-house that provides a cooler environment for the pigs. This, together with the premium price of the pigs that could be fetched from this eco-friendly production system, would make it a technically and economically viable system in the long run.