Study of the prospects for agricultural utilization of sludge produced from WWTPS in North Central Algeria

• Published in: Desalination and water treatment 2015-07, Vol.55 (5), p.1152-1166
• Main Authors: Nakib, Maamar, Kettab, Ahmed, Berreksi, Ali, Mandi, Laila
• Format: Article
• Language: English
• Subjects: Animal wastes; Cattle manure; Comparative studies; Composts; Fertilizers; Manures; Mineralization; Nitrogen; Organic matter; Organic phosphorus; Recovery; Safety; Sewage sludge; Sludge; Urban studies; Wastewater treatment plants; Water treatment
• ISSN: 1944-3986; 1944-3994; 1944-3986
• DOI: 10.1080/19443994.2014.926260

The objective of this study is to investigate the sewage sludge of six wastewater treatment plants (WWTPs) in North Central Algeria for agricultural reuse. After a brief description of the region (climate, distribution of soils, and crop types), a quantitative and qualitative examination of the sludge produced was conducted in addition to a comparative study of urban compost and cattle manure. The selected agronomic parameters were dryness, percentage of organic matter (OM), as well as the contents of nitrogen, phosphorus, potassium, and calcium. An average OM of soils of 1.3% and a minimum value of 0.2% made it clear that the urgency of providing this type of amendment was warranted. The sewage sludge in this study was characterized by carbon to nitrogen ratios lower than those of manure and compost due to its stabilization process at the WWTPs on one hand, and the presence of recalcitrant lignin compound mineralization in compost and manure, on the other hand. The spreading of sludge in the region covered a very small surface area, not exceeding 0.50% of the overall agricultural area. The quantities of fertilizers produced by sludge were significant and often exceeded agricultural requirements. Yet, due to the insufficient amounts of OM provided by sewage sludge, there was a need to rely on alternate sources such as manure and/or urban compost.