Evaluation of the reaction capacity of wastewater coliforms to photocatalysis with dip coating techniques

Abstract

Introduction: The presence of fecal and total coliforms in wastewater are indicators of water quality and the degree of exposure and impact of human activities on it. Objective: Apply photocatalysis processes with sunlight and the Dip - Coating method for the reduction of coliforms in wastewater. Objective: Apply photocatalysis processes with sunlight and the Dip - Coating method for the reduction of coliforms in wastewater. Methodology: The process included perpendicular immersion and subsequent extraction of the substrate at a controlled speed in a solution prepared for the formation of the Titanium Dioxide film, drainage in the same equipment, evaporation and drying known as the DIP_coating method together with the solar disinfection of the water (SODIS) that used solar energy to destroy pathogenic microorganisms that cause water-borne diseases, relating UV-A radiation, which had a germicidal effect, and infrared radiation, responsible for raising the temperature of the water. The combined use of UV-A radiation and heat produced a synergistic effect that increased the efficiency of the process. Four experimental units were used: two were applied by the SODIS method and the other two applied SODIS with TIO2 in the Dip-coating method. The residual water samples were placed in PET plastic bottles prepared in three solutions (10^-1, 10^-2 and 10^-3), performing the microbiological analysis_quantification of coliforms in Compact Dry EC plates incubated for 24 hours at 35 ° C. Results: A significant reduction was evidenced, especially in the 10^-3 dilution, accounting for the case of fecal coliforms in the SODIS method: 3900 MPN / 100ml and DIP-COATING: 100 MPN / 100ml; and for total coliforms in SODIS: 12500 NMP / 100ml and DIP-COATING: 1100 NMP / 100ml, at optimal treatment conditions of 180 min at 42 ° C. Conclusions: the exposed conditions and suitable climatic conditions give the maximum reduction effect by combining the two SODIS / DIP-Coating methodologies where the photocatalysis process with sunlight microbiologically improved the water quality where titanium dioxide was a low-cost semiconductor , easy accessibility, low toxicity, resistance to photo corrosion and catalytic efficiency