The Effects of UV Treatment on Microbiological Disinfection of Household Greywater

Abstract

The efficiency of Ultraviolet sterilization units to improve the microbial quality of household greywater for recycling of water has become a popular title all around the world. To improve the microbiological quality of household greywater, different volume water were artificially inoculated with approximately 6 log/ml of Escherichia coli, Staphylococcus aureus, Enterococcus feacelis, Bacillus cereus, Aspergillus niger and inactivation of 5W and 11W UV lamps were determined for individual suspensions and mixtures during 1 hour  as a function of time. The performance of disinfection method was evaluated by classical microbiology analysis methods where total aerobic counts and specific agar plates were used. Treatments at 5 W UV lamp is reduced the S.aureus and E. coli to 0-1 log cfu/ml, however inactivation of A. niger and E. feacelis obtained with this lamp was nearly 2.5 log/ml; for the individual inoculations. 11W UV radiation has significant effect on selected microorganisms including both bacterial and fungal species. On the following tests; effect of stainless steel and polypropylene housing was investigated by mixtures of 4 different microorganisms for 11 W UV source. Different housing material didn’t shown to be having significant effect in the test conditions. On the other hand inactivation effect found to be lower when mixture of microorganisms is used. This is thought to be resulting from the higher turbidity of the test solution; which is a very important criteria for UV applications. This project shows UV disinfection treatment has an outstanding inactivation effect on reduction of microorganism in water. For the improved water quality, system parameters (higher power, replacement of lamps, water flow rate and application period, turbidity and initial quality of fed water…) should be investigated in detail. Alternative technologies should also be taken in to consideration for improved applications.