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    • cholecystokinin receptor Introduction An estimated of wastew

    2018-10-29

    Introduction An estimated 90% of wastewater in developing countries undergoes no treatment (Corcoran et al., 2010). For example in Kumasi, Ghana, only 8% of the wastewater undergoes some form of treatment (Keraita et al., 2002), while the remaining raw sewage flows to wetlands linked to small streams or is discharged via storm water drains and gutters into surface streams, along which, irrigated vegetable production is practiced (Keraita et al., 2002). An estimated 60% of the formal irrigation (irrigation systems developed and managed by the government) in Ghana is by low quality water collected directly from these streams, rivers or from on-farm ponds containing river or drainage water (Obuobie et al., 2006). The same applies for many other developing countries, where the most commonly used water source for irrigation in urban farming is water from wastewater-contaminated sources (Mateo-Sagasta et al., 2013). Foods produced by irrigation with wastewater are estimated to be consumed by 10% of the world\'s population (Corcoran et al., 2010) and can pose a significant health risk to cholecystokinin receptor and farmers. A major health risk associated with irrigation by feces contaminated waters are pathogens including oocysts of the protozoan parasite Cryptosporidium. Protozoan parasites are commonly found in different freshwater sources. For instance, Amoros et al. (2010) demonstrated 47.5oocystsL in water used for irrigation of lettuce in Spain and in Mexico, 98% of irrigation water samples contained Cryptosporidium, Giardia or both parasites (Chaidez et al., 2005). Protozoa are transmitted by the fecal oral route, e.g. by consuming (oo)cyst contaminated water, fruit, and vegetables, in particular when produce is consumed raw. Cryptosporidium spp. can cause severe or life-threatening gastrointestinal disease in humans as well as animals, in all regions of the world (O\'Donoghue, 1995; Okhuysen et al., 1999). The importance of irrigation water as a source of Cryptosporidium contamination is underlined by findings of oocysts on vegetables irrigated with low quality water. A study determining the level of Cryptosporidium-contamination on 496 vegetable samples from 115 farms around Tehran, Iran, found that 6.6% of the samples were contaminated with Cryptosporidium. The irrigation water was associated with the contamination rate, and the Cryptosporidium contamination was 33.3% higher when wastewater rather than well water was used for irrigation (Ranjbar-Bahadori et al., 2013). In Ghana, Cryptosporidium oocysts were found on 43% of freshly picked lettuce samples from three farms where the irrigation water originated from a nearby stream receiving untreated wastewater from the city of Kumasi (Petersen et al., 2014). In Spain, 63% of lettuce irrigated with water from a wastewater-fed irrigation canal contained Cryptosporidium (Amoros et al., 2010). Cryptosporidium is likely to survive in or on moist food for months and are infectious at low dosages (Okhuysen et al., 1999). A high degree of oocysts removal is therefore required if contaminated water is to be used safely in irrigated agriculture. Low quality water is usually characterized by high turbidity. For example in Ghana, turbidity levels at approximately 200 and 791 nephelometric turbidity units (NTU) have been reported in water used for irrigation (Keraita et al., 2008; Petersen et al., 2014); and high turbidity has been shown to correlate positively with pathogen levels in water (Dorner et al., 2007; Nnane et al., 2011). Thus, turbidity reduction is an important quality parameter when evaluating the effect of wastewater treatment, and turbidity reduction is expected to correlate with reduction of Cryptosporidium oocyst levels in low quality water as previously observed for helminth eggs (Sengupta et al., 2012b). Turbidity removal is generally achieved using chemical coagulants, but in recent years, there has been a resurgence of interest in the use of natural materials for water treatment due to cost and associated health and environmental concerns of organic polymers and inorganic chemicals commonly used as coagulants (Ghebremichael and Hultman, 2004). Among plant materials, Moringa oleifera (MO) seeds have shown promising qualities as effective coagulants for water treatment (Katayon et al., 2006).