THE DIFFERENT CONCENTRATION INFLUENCES OF WASTEWATER TREATMENT PLANT (WWTP) EFFLUENT ON Chlorella vulgaris DENSITY AND GROWTH RATE
Siti Siwi Wulandari (1), Tri Retnaningsih Soeprobowati (2), Kismartini (3)

1Master of Environmental Science, School of Postgraduate, 1) Diponegoro University- email: sitisiwiwulandari[at]gmail.com
2) Biology Departement, Faculty of Science and Mathematics, School of Postgraduate, Diponegoro University- Cluster of Paleolimnology (Cpalim)
3) Department of Public Administration, Faculty of Social and Political Sciences, Diponegoro University

Abstract

Household wastewater processing in the Communal Wastewater Treatment Plant (WWTP) by Guyub Rukun Community at Tegalsari Hamlet, Salatiga City, Indonesia, is expected to reduce water pollution in the Cengek River. However, according to effluent testing, high concentrations of TP, COD, and BOD were found. This study aims to conduct laboratory-scale phycoremediation experiments using Chlorella vulgaris with media mixed using Communal WWTP effluent. Samples were taken from the outlet pipe to obtain household wastewater treatment effluent. Sampling was done using the grab sampling method at 2 PM during high sanitation activity. Based on laboratory tests, the highest Chlorella vulgaris density for 0% effluent concentration was 77.75 x 104 cells/mL (day 7), 66.13 x 104 cells/mL (day 6) in 20%, 126.13 x 104 cells/mL (day 7) in 40%, 69.38 x 104 cells/mL (day 6) in 60%, 188.88 x 104 cells/mL (day 6) in 80%, and 232 x 104 cells/mL (day 8) in 100%. The best growth rate at 0% effluent concentration was 3.87 cells/mL/day (day 6), 3.52 cells/mL/day (day 6) in 20%, 4.25 cells/mL/day (day 6) in 40%, 3.56 cells/mL/day (day 5) in 60%, 4.69 cells/mL/day (day 6) in 80%, and 4.99 cells/mL/day (day 7) in 100%. The results showed that the best density and growth rate of Chlorella vulgaris were at 100% effluent concentration, followed by 80%, 40%, 0%, 60%, and 20% effluent concentrations. The TP, TN, and Nitrate content in the effluent of Communal WWTP can be utilized as macronutrients in microalgae growth.

Keywords: Effluent, Microalgae, Phosphate, Nutrient, Density, Growth

Topic: Interdisciplinary Earth Science and Technology