Reuse of domestic wastewater treated in macrophyte ponds to irrigate tomato and eggplant in semi-arid West-Africa: Benefits and risks

Abstract

a b s t r a c tThe scarcity of freshwater resources is a critical problem in semi-arid zones and marginal quality water is increasingly being used in agriculture. This paper aimed at evaluating the physico-chemical and biological risks on irrigated soils and fruits of macrophyte treated wastewater (TWW), the nutrients supply, and the effect on tomato and eggplant production in semi-arid Burkina Faso. During three years of experiments, treated wastewater was used, with fresh water as control, in combination with or without mineral fertilizer application at recommended rate (140 kg N/ha + 180 kg P 2 O 5 /ha + 180 kg K 2 O/ha). The study revealed that the treated wastewater provided variable nutrients supply depending on year and element. The treated wastewater without mineral fertilizer improved eggplant yield (40% in average) compared to the freshwater. Both crops responded better to mineral fertilizer (52% for tomato and 82% for eggplant) and the effects of the treated wastewater and fertilizer were additive. As the N supply of TWW was very unsteady (8-227% of crop need), and P 2 O 5 supply did not satisfy in whole crop need (3-58%) during any of the three years of experiment, we recommended that moderate N and P 2 O 5 fertilizers be applied when irrigating with TWW in semi-arid West-Africa. On the contrary, the K 2 O supply was more steady and close to crop requirement (78-126%) over the three years of experiment and no addition of K fertilizer may be needed when irrigated with TWW. Faecal coliforms and helminth eggs were observed in treated wastewater and irrigated soils at rate over the FAO and WHO recommended limits for vegetable to be eaten uncooked. Tomato fruits were observed to be faecal coliform contaminated with the direct onfoliage irrigation with treated wastewater. Our results indicate that treated wastewater can effectively be used as both nutrients source and crop water supply in market gardening in the semi-arid Sub-Saharan West Africa (SSWA) where freshwater and farm income are limiting. Yet consumers should properly cook or disinfect treated-wastewater irrigated vegetables before eating, and market gardeners should also be careful manipulating treated wastewater to avoid direct health contamination in this environment.

Performance of the Municipal Wastewater Treatment Plant for Removal of Listeria monocytogenes

“…According to Kiziloglu et al (2007), wastewater has a high nutritive value that may improve plant growth, reduce fertilizer application rates, and increase productivity of poor fertility soils. Diverse studies have indeed shown that TWW irrigation increases soil organic matter (Mañas et al 2009;Jueschke et al 2008;Kiziloglu et al 2007) as well as the concentrations of different nutrients involved in plant growth such as nitrogen (N), phosphorus, iron, manganese, potassium, calcium, magnesium, and others (Akponikpe et al 2011;Rezapour and Samadi 2011;Sacks and Bernstein 2011;Mañas et al 2009;Gwenzi and Munondo 2008;Kim et al 2007; Kiziloglu et al 2007;Angin et al 2005). Conversely, the use of TWW for irrigation can have detrimental effects on soil quality.…”

“…Perhaps the most evident public health qualms are linked to the presence pathogens. Several studies have reported high count of total coliforms and fecal coliforms in crops irrigated with TWW (Akponikpe et al 2011;Sacks and Bernstein 2011;Mutengu et al 2007;Rai and Tripathi 2007), while others have detected bacterial pathogens such as Salmonella, Streptococci, Clostridium, Shigella, and Vibrio spp. (Mañas et al 2009;Samie et al 2009).…”

Treated Wastewater Irrigation Promotes the Growth and Nodulation of Acacia Species

“…The incensements in the seedling height were 69% and 13% for A. ampliceps and A. origena, respectively, while seedling diameter was 13% and 5.5% for A. ampliceps and A. origena, respectively, in the PTWR treatment than in the MW treatment. Several studies have also showed increasing in the growth parameters of trees and crops after irrigation with treated wastewater (Kiziloglu et al, 2008;Bedbabis et al, 2010;Akponikpèa, 2011;Pandey andSrivastava, 2012, andSelahvarzi andHosseini, 2012). Moreover, Carvalho et al (2012) found that the height and nodulation of Leucaena leucocephala and Mimosa caesalpiniaefolia significantly increased when treated with sewage effluent and inoculated with Rhizobium.…”

Economic Assessment of an Integrated Membrane System for Secondary Effluent Polishing for Unrestricted Reuse

“…It is believed that soon, wastewater treatment levels will be also dictated by the requirements of local recipients and not only by some general regulations [27]. The methods for evaluating the overall design and operation of wastewater treatment systems are therefore important for both economic and environmental considerations [28].…”