REMOVAL OF TERATOGENIC 2,4- DICHLOROPHENOXYACETIC ACID USING ACTIVATED CARBON IN BIOSAND FILTERED DRINKING WATER, A CASE OF AHERO IRRIGATION SCHEME

Abstract

Access to safe and clean drinking water is a major challenge to the people living around Ahero Irrigation (AIS). Water source in the area is constantly and increasingly polluted by agrochemical like pesticides from rice farming. Point of use treatment technology is inexpensive and effective in drinking water treatment. Bio-Sand Filter (BSF) is one of such technologies that have been implemented in Kenya and over 20 countries worldwide. While the health benefits of using a BSF in terms of reduction of diarrheal disease have been fairly well documented, little research has focused on the ability of this technology to remove other contaminants in drinking water that pose health concerns especially pesticides. 2,4-dichlorophenoxyacetic acid (2,4-D) is a herbicide extensively used in irrigation scheme. The residues of 2,4-D are present in air, water, soil and edibles. 2,4-D has been known to cause cellular mutations which can lead to cancer. The neurotoxic, immunosuppressive, cytotoxic and hepatoxic effects of 2,4-D have been well documented. But there is a lot of controversy with the teratogenic effects of 2,4-D. Xenopus laevis was used to evaluate the teratogenic effect of this pesticide. Structured questionnaires were administered to the people living around AIS in order to obtain information on their water sources and extent of use of 2,4-D. Then purposive sampling was used to collect water sample from key sources in the study area, then spiked with 2,4-D at different concentrations then passed through BSF, and analyzed for presence of 2,4-D using HPLC. The water that was passed through BSF was then passed through Granular activated carbon (GAC) and locally activated charcoal from bamboo (LACB) each and analyzed for the removal of 2,4-D. BSF was able to remove 2,4-D to a small amount of up to 6.1±0.43% (SE) at 5.4 mg/l initial concentrations, while GAC had the highest removal efficiency of (95.27±0.10%) (SE) and (91.49±0.15%) (SE) for bamboo at 238.7 mg/l 2,4-D initial concentration each. 2,4-D teratogenic index was 1.003. BSF is not effective in the removal of 2,4-D, hence its recommended that the water passed through BSF should be also passed through activated carbon in order to enhance safety of drinking water with respect to both the chemical and microbiological contaminants.