Distribution of Detergent Waste in the Environment and the Removal by Using Photocatalytic Degradation and Coagulation Methods

Aims: This study is aimed to determine the distribution of detergent contamination in the Code River and the ability to remove it from laundry wastewater samples by using photocatalytic degradation and coagulation methods.

Place and Duration of Study: The study was located at the Code River close to Gadjah Mada University, Yogyakarta, and the research was conducted for 6 months (June-November 2013).

Methodology: The water samples used in this study consist of waste water (produced from laundry activities) and river water (before and after the outlet of laundry waste disposal). Analysis of anionic surfactant and phosphate were carried out by UV/visible spectrophotometric methods using methylene blue and ammonium molybdate, respectively as complexing agents. The surfactant removal was studied using photocatalytic degradation and that of phosphate by coagulation methods. The photocataltyic reaction was carried out in batch technique by irradiating the artificial waste in the presence of TiO2 powder as photocatalyst with UV lamp. The coagulation was conducted by batch technique using 3 types of coagulants, that are alum (Al3+), ferroin (Fe3+), and calcium (Ca2+), in which the influence of reaction time was studied.

Results: The results indicate that the river water which is located at the points before and after the disposal point of the laundry waste water contain anionic surfactant and phosphate.The content of the anionic surfactant (198 mg/L) and phosphate (52 mg/L) in the laundry waste water (taken directly from the laundry process) are found to be much higher than the quality standard level (0.2 mg/L and 0.1 mg/L for surfactant and phosphate respectively). Therefore, it is clear that such waste water has to be treated before being disposed. The present study shows that the waste water treatment by photodegradation method catalyzed by TiO2 can decrease the surfactant concentration effectively, and the effectiveness is controlled by TiO2 dose and reaction time. The maximum removal of surfactant (90%) from 50 ml of the waste water can be obtained by using 30 mg of TiO2 for 24 h of reaction time. By using coagulation process, the concentration of phosphate in the waste water can be decreased as much as 10-70%, depending on the type of coagulants. The most active coagulant is Fe3+ followed by Al3+ and Ca2+ due to their affinity in poly nuclear formation.

Conclusion: The water streams in the Code River are found to be contaminated by surfactant and phosphate in low to medium level. The removal of the surfactant in the laundry waste water was successfully carried out by photodegradation method catalyzed by TiO2, while the phosphate concentration can be decreased by coagulation method.