Bacteriological quality of urban waste water used in irrigation of vegetables and on the vegetable lettuce (Lactuca Satavi)

Abstract

This study involves the determination of total viable counts, escherichia coli, salmonella and vibrio species in lettuce and the water used for irrigation at some selected farms in Accra by the use of Pour Plate Methods and by means of selective media and subsequent comparison of the levels of contamination of the samples at the selected farming sites. A total of 20 samples thus 10 for the wastewater and the other 10 for the lettuce were taken from five main irrigation farms namely Accra –Tema Motorway I (ATMI), Accra –Tema Motorway II (ATM2), East-Legon, Adjiringanor (E-Legon), Dzorwulu (DL) and CSIR-Head Office (CSIR-H). In June, the total coliforms count of the wastewater and lettuce ranged between 1.209 x10⁵ to 1.96 x 10⁴ and 4.65 x 10⁴ to 3.7 x 10³ cfu/100ml respectively. In July, the values for the wastewater and lettuce raged from7.44 x10⁴ to 5.0 x 10² cfu/100ml respectively. In June, the population of E. Coli in the wastewater and lettuce ranged between 1.023 x 10⁵ and absent (0)cfu/100ml respectively. In July, the population of E.coli was between 6.51 x 10⁴ and 2.0 x 10³ cfu/100ml for the wastewater and lettuce cfu/100ml respectively. In June, the population of salmonella spp in the wastewater and lettuce ranged between 1.65 x 10⁴ to absent (0) and 2.79 x10⁴ to 1.7 x103cfu/100ml respectively. In July, the population of salmonella spp for the wastewater and lettuce raged from 3.5 x 10³ to 9.3 x 10³ and 2.76 x10⁴ to 2.0 x10³ cfu/100ml respectively. In June, the population of Vibrio spp in the wastewater and lettuce ranged between 6.7x10³ to 3.2x10³ and 1.52x10⁴ to absent (0)cfu/100ml respectively. In July, the population of Vibrio spp was between 6.7 x 10³ to 3.2 x 10³ and 4.1 x 10³ to 1.5 x 10³ cfu/100ml for the wastewater and lettuce respectively. In conclusion, the wastewater used for the irrigation of vegetables in most parts of the Accra metropolitan is contaminated with bacteria’s most especially E. coli, Salmonella and Vibrio spps