This study investigated the application of the deep row entrenchment method under South African conditions with the aim of establishing whether the use of pit latrine and wastewater sludges as a fertilizer substitute for the agro-forestry sector can be recommended and thereby also establishing a safe and beneficial technique for the disposal of faecal and wastewater sludges. The development of the deep row entrenchment method in the 1970s and subsequent studies were reviewed as were the South African guidelines for the utilisation of wastewater sludge. No guidelines currently exist for the classification or utilisation of pit latrine sludge. Pit latrine sludge was buried at different loading rates on a sandy site at a disused oxidation pond in Umlazi, south of Durban, and wastewater sludge from the Howick Wastewater Treatment Works was entrenched at a Sappi research site near Howick. The sites were characterised and monitored over time in order to document the movement of nutrients out of the trenches and changes in groundwater over time. The HYDRUS-2D was used to model the movement of soil-water, phosphorus and nitrate. The fate of pathogens over time was also investigated. Tree growth was monitored in order to document differences in growth rates between trees provided with different loading rates of sludge and control groups. Two smaller studies were also conducted to investigate the impact of sludge on tree growth under controlled conditions and the application of deep row entrenchment for on-site sludge disposal.

Bibliographic information

Still, D., Louton, B., Bakare, B., Taylor, C., Foxon, K., Lorentz, S. (2012). Investigating the potential of deep row entrenchment of pit latrine and waste water sludges for forestry and land rehabilitation purposes WRC Project No. K5/1829 Water Reserach Commission (WRC), South Africa

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Food security and productive sanitation (WG5)Groundwater protection (WG11)Faecal sludge treatment processesFaeces or faecal sludgeEnglish

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