Assessing the quality of sewage sludge as an agricultural soil amendment in Mediterranean habitats

Abstract

Purpose Municipal sewage sludge generated from three operational wastewater treatment plants, located in the Bekaa valley of Lebanon, was assessed for its potential use as agricultural soil amendment. Methods Sludge samples were taken from three treatment plants located in the villages of Iaat, Ablah and Joub Jannine during the summer season of 2018, from June to September, on a monthly basis. The evaluation was based on characterizing the physicochemical parameters such as the metal content, the pathogenic microorganisms (Salmonella, E.Coli, Staphylococcus aureus, Helminth eggs, Ascaris, Acinetobacter) and the phytotoxicity-stability indicators of the sludge samples. Results The obtained results were compared to the Lebanese guidelines for sludge reuse in agriculture. For the physicochemical analysis, all the samples showed a possibility to be used in agriculture due to the high content of minerals and organic matter. Considering the metal content of sludge, Iaat and Ablah sludge were classified as Class A according to the Lebanese guidelines; however, sludge from Joub Janine was classified as B due to its high content of zinc that exceeded the limit of 700 ppm. Helminth eggs and Salmonella were absent in the sludge samples. Pathogenic organisms, mainly E. coli, were detected in Iaat dry sludge, Staphylococcus aureus was present in Joub Jannine sludge and Acinetobacter in Ablah station (> 100 CFU/100 g). Conclusion It is recommended to submit the sludge which did not meet the required criteria, for further treatments, particularly the composting process to reduce the metal content and pathogenic microorganisms for a safer reuse in agriculture.

Phosphate sludge: opportunities for use as a fertilizer in deficient.

“…The results obtained from the physicochemical characterization of PS are shown in Table 1. The pH (8.20) was slightly alkaline, probably due to the high content of water-soluble Ca (Romanos et al, 2019). The EC was low in the range of 0.77 mS/cm, mainly due to the low concentrations of soluble salts such as K + , Na + , PO 4 3-, and SO 4 2-(Table 1).…”

Toward achieving sustainable management of municipal wastewater sludge in Egypt: The current status and future prospective

“…Despite the economic benefits of using sludge for renewable energy production and land reclamation, there is a need to comply with restrictions for pathogens or potentially-pathogenic organisms. Due to the lack of any sludge stabilization facilities in the majority of WWTPs in Egypt, the current excess municipal wastewater sludge is expected to have a high content of pathogens, representing the most critical obstacles for safe use in agriculture [34,35]. For all analyzed samples, Ascaris was not detected; however, the indicator organisms faecal and total coliform were present at relatively high values (1.8 � 10 4 to 1.6 � 10 9 MPN/100 mL), showing the importance for establishing sludge stabilization facilities to achieve high pathogens inactivation for safe reuse.…”

The formation of the leaf surface area and biomass of the miscanthus giganteus plants depending on the sewage sludge rate

“…Municipal sewage sludge considered as potential source of macroelements, which recovered during the production of energy crop biomass [13 -16]. It is composed of a wide range of organic matter (OM), microorganisms, macroand micro-nutrients, non-organic and organic micro pollutants [17] All these components indispensable for proper functioning of plants in optimum quantities and proportions for fertilization purposes [18]. However, sewage sludge also contains heavy metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) [19][20][21].…”