A review of the environmental pollution originating from the piggery industry and of the available mitigation technologies: towards the simultaneous biofiltration of swine slurry and methane

Abstract

In Canada, the piggery industry is an essential part of the agricultural sector, but the main waste product of this industry, swine slurry, is particularly harmful to the environment. The anaerobic storage conditions and the excessive use of slurry for agricultural fertilization contribute, respectively, to the emission of greenhouse gases and to aquatic pollution. This paper provides a review of these environmental concerns and of the existing mitigation technologies. Water pollution from swine slurry is associated with the nutrients it contains, such as nitrogen and phosphorous, while the main greenhouse gases produced by the piggery industry are methane and nitrous oxide. Available technologies can valorize the slurry through agricultural fertilization, reduce greenhouse gas emissions, by limiting nutrient availability for example, or treat the effluents using solid – liquid separation, flaring or biological processes. Specific attention is paid to biofiltration due to its potential to simultaneously treat these two types of pollution.

Dynamics of bacterial metabolic profile and community structure during the mineralization of organic carbon in intensive swine farm wastewater

“…Intensive swine industry has rapidly developed in the past few years (Deng et al, 2007;Bernet and Béline, 2009;Girard et al, 2009;Fernandes et al, 2012) and generates large amounts of excrements and wastewater in concentrated areas. One of the most common waste management practices is the land application of swine wastewater as fertilizer or, in some regions, discharge of wastewater to nearby fields and water bodies after simple treatment (Zhou et al, 2013).…”

Function and limits of biofilters for the removal of methane in exhaust gases from the pig industry

“…With the intent to satisfy the demand, the Canadian agriculture sector supplies up to 80 % of the pork imported in the USA (United States Department of Agriculture 2009), which corresponded to 308,000 tons of pork in 2008 (Agriculture and Agri-Food Canada 2010). In Canada, this industry generated 7 % of annual agriculture revenues in 2009 with more than 2.9 billion dollars (Statistics Canada 2011) and sustained 64,000 direct and indirect jobs in 2007 (Girard et al 2009). …”

“…For example, the legislation in the province of Quebec allows farmers to spread their manure between April 1 and October 1 of each year (Government of Quebec 2005). It is estimated that a pig can produce 1 m 3 of slurry during its lifetime (Girard et al 2009). With an average number of 2010 pigs per farm in Quebec (Canadian Pork Council 2011), slurry storage generates large volumes of slurry.…”

Simultaneous treatment of methane and swine slurry by biofiltration

“…7 Swine slurry can also be treated by different physico-chemical methods, but biological processes, both aerobic and anaerobic, are generally used. 8 Methane can be treated by flaring, but a concentration above 130 g m −3 is required for direct combustion, 9 which is not usually found on pig farms. Biological oxidation of CH 4 is also possible and it can be carried out directly in slurry storage reservoirs by adding a surface crust.…”

“…Biofiltration, which uses microorganisms immobilized on a filter bed, has the potential to treat both swine slurry and CH 4 within the same bioreactor. 8 For the treatment of municipal and industrial wastewaters, biofiltration has been used for nearly 100 years, 13 but it has only recently been applied to swine slurry. 14 The biofiltration of CH 4 has been widely studied for sanitary landfills, 15 but there is little research for the treatment of CH 4 from the piggery industry.…”