Role of livestock effluent suspended particulate in sealing effluent ponds

• Published in: Journal of environmental management Vol. 154; pp. 102 - 109
• Main Authors: Bennett, J. McL, Warren, B.R.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2015; Academic Press Ltd
• Subjects: Aluminum Silicates - analysis; Animals; Biodegradation, Environmental; clay; Colloid; Contamination; Effluents; Feeds; food production; Groundwater; groundwater contamination; hydraulic conductivity; Livestock; Mathematical models; Particulate Matter; Ponds; population growth; Pore blockage; seepage; Soil - chemistry; Threshold electrolyte concentration; topsoil; Waste Disposal, Fluid - methods; Wastewater; Water Pollution - prevention & control; Threshold electrolyte concentration; Pore blockage; Wastewater; Colloid
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2015.02.032

Intensive livestock feed-lots have become more prevalent in recent years to help in meeting the predicted food production targets based on expected population growth. Effluent from these is stored in ponds, representing a potential concern for seepage and contamination of groundwater. Whilst previous literature suggests that effluent particulate can limit seepage adequately in combination with a clay liner, this research addresses potential concerns for sealing of ponds with low concentration fine and then evaluates this against proposed filter-cake based methodologies to describe and predict hydraulic reduction. Short soil cores were compacted to 98% of the maximum dry density and subject to ponded head percolation with unfiltered-sediment-reduced effluent, effluent filtered to <3 μm, and chemically synthesized effluent. Reduction in hydraulic conductivity was observed to be primarily due to the colloidal fraction of the effluent, with larger particulate fractions providing minimal further reduction. Pond sealing was shown to follow mathematical models of filter-cake formation, but without the formation of a physical seal on top of the soil surface. Management considerations based on the results are presented. •Fine colloidal fraction of effluent was responsible for soil seepage reduction.•Effluent fine fraction was comprised of inorganic particulate, likely clay.•Sediment reduced and filtered effluents were effective in reducing pond seepage.•A filter-cake model describes seepage reduction, but without observed filter-cake.•Effluent chemistry was shown to have variable effect on soil permeability.