Waste Treatment Lagoons

Primary reference(s)

Spellman, F.R. and R.M. Bieber, 2012. Environmental Health and Science Desk Reference. Government Institutes, 807.

Additional scientific description

Effluents from livestock industrial production are commonly discharged into the environment or stored in ‘lagoons’, from which waste may spill or leak into nearby streams and groundwater supplies. Noxious gases escape into the atmosphere, subjecting downwind neighbours to sickening odours and contributing to atmospheric aerosol formation, build-up of greenhouse gases and acid rain (FAO, 2007).

The term ‘lagoon’ is often misused, mistakenly including manure storage basins as lagoons (Hamilton et al., 2006). Manure storage basins are not meant to provide significant biological treatment or long storage periods (Livestock and Poultry Environmental Learning Community, 2019).

‘Lagoons’ can be anaerobic, aerobic, naturally-aerobic, mechanically aerated and facultative, depending on their loading and design (Miller et al., 2011). Lagoons rely on physical, chemical, and biological processes to degrade manure (Hamilton et al., 2006; Miller et al., 2011).

Metrics and numeric limits

Not available.

Examples of drivers, outcomes and risk management

In recent decades, livestock production (e.g., pig farms, dairies, poultry industry) has increased rapidly. Increased production comes from industrial farms clustered around major urban centres (FAO, 2007). The livestock waste is a major source of greenhouse gases, air pollutants, harmful pathogens and odour (Sorathiya et al., 2014). Concentrations of animals (including intensive farming) and animal wastes close to dense human populations can cause large-scale environmental problems including soil, water, air pollution, and biodiversity loss and may negatively impact human health. It is potentially more dangerous if such concentrated production is conducted in areas near water sources (FAO, 2007).

The environmental and public health risks of industrial feedlots and effluent lagoons can be limited by ensuring that they are not located too close to each other, to streams and aquifers and to densely populated communities. Environmental damage can be reduced further by encouraging and enforcing standards for the design and construction of buildings and lagoons to conform with approved manure management system (FAO, 2007). Meat processing plants produce large amounts of slaughterhouse wastewater, treatment and final disposal (Bustillo-Lecompte and Mehrvar, 2017).

Livestock waste lagoons and manure storage basins may spill or leak into nearby streams and groundwater supplies. Furthermore, cracks, improper construction, increased rainfall, storm or stronger than normal winds can cause lagoon overflow. Ponds or lagoons used to store effluents should be lined to reduce leaching and be big enough to allow for manure storage at times when application on crops is not suitable, such as during the rainy season (FAO, 2007). Overflow can spread harmful bacteria, pesticides, animal antibiotics, additional oestrogens, heavy metals, and protozoa into the groundwater supply and contaminate surrounding areas and these could be identified as socio-economically generated sediments (Sharma and Singh, 2015).

Pollution associated with animal waste management in intensive livestock production include (FAO, 207):

• Leaching of nitrates into groundwater, threatening drinking water supplies.
• Eutrophication of surface water, as nitrogen, phosphorus and other nutrients are discharged or run off into streams, damaging wetlands and fragile coastal ecosystems, and fuelling algae ‘blooms’ that use up oxygen in the water, killing fish and other aquatic life.
• Build-ups of excess nutrients and heavy metals in the soil, damaging soil fertility and shrinking arable land resources.
• Contamination of soil and water resources with pathogens, heavy metals or drug residues.
• Release of ammonia, hydrogen sulphide, methane, carbon dioxide and other gases into the air, some of which can negatively impact health hazards, damage crops and ecosystems.

Effective policies and legislation to regulate intensive livestock operations and support environmentally and economically sustainable approaches, the use of adequate practices and technologies are of high importance for addressing these challenges and mitigating production of the pollutants. Livestock waste is a major source of nutrients and energy which contributes to improving the circular bioeconomy. Proper management and use of livestock waste as a fertiliser or for conversion into biogas, compost and vermicompost is a useful means to increase crop yield, sustainability, and income (Sorathiya et al., 2014).