Incidence of Escherichia coli in Vegetable Crops and Soil Profile Drip Irrigated with Primarily Treated Municipal Wastewater in a Semi-Arid Peri Urban Area

This study investigates the incidence of Escherichia coli in cauliflower, bitter gourd and soil profile drip-irrigated with municipal wastewater in a semi-arid peri-urban area in India. There were four treatments: drip irrigation with primarily treated municipal wastewater through inline (non-pressure compensating) surface drip (T1), inline subsurface drip (T2), bioline (pressure compensating) subsurface drip (T3) and bioline surface drip (T4). Results revealed that T1 had the highest concentration of E.coli (35 +/- 2.66 and 25 +/- 2.26 colony forming unit (CFU) g(-1)) and T3 had the lowest concentration of E. coli (29 +/- 2.29 and 18.9 +/- 2.04 CFU g(-1)) for cauliflower and bitter gourd, respectively. In bitter gourd top fruits (1 m above the ground level), the E. coli count was significantly lower (p < 0.05) than in the surface level fruits. There was also a considerable reduction of E. coli counts in bioline drip lateral as compared to the inline drip. A higher concentration of E. coli (470 +/- 70.5 and 410 +/- 36.9 CFU g(-1) soil) was also found in the top soil (0-0.15 m) in T1 treatment, while the minimum (154 +/- 13.86 and 95 +/- 14.25 CFU g(-1)) was observed in T3. Hence, bioline drip lateral may be a better option for wastewater irrigation as compared to inline drip to reduce microbial contamination of crop and soil.