Micropollutant Removal from Laundry Wastewater in Algal-Activated Sludge Systems: Microbial Studies Aishwarya Pandey & Keerthi Katam & Prasanth Joseph & Satoshi Soda & Toshiyuki Shimizu & Debraj Bhattacharyya Received: 6 February 2020 /Accepted: 7 July 2020 # Springer Nature Switzerland AG 2020 Abstract The main objective of this research was to study the feasibility of using algal and algal-activated sludge systems in treating laundry wastewater. Three different types of systems—green microalgae (system A), diatoms + activated sludge (system B), and green microalgae + activated sludge (system C)—were stud- ied at six different solid retention times (SRT)—6, 8, 10, 12, 14, and 16 days—to evaluate their performance in removal of total organic carbon (TOC), total nitrogen (TN), anionic surfactants, and micropollutants with added trace elements. System B showed relatively better performance in removal of TOC (79%) and TN (90%). A total of 64 compounds were detected in influent when analyzed by LC-MS, of which 19 were grouped under herbicides, pesticides, and insecticides, 25 under phar- maceuticals, and 20 under others. Linear alkylbenzene sulfonate (LAS) was detected only in the effluent of system A and was not detected in both system B and system C. Grotan OX, an anti-microbial, was the com- pound with least removal in all the systems. The bacte- rial LAS degrader/tolerant plate count in system B at 16- day SRT was 2000 CFU/mL, 50 times more than the plate count of system C (40 CFU/mL). The LAS degrader/tolerant bacterial species identified were Aeromonas caviae and Klebsiella pneumonia in both systems B and C. The LAS degrader/tolerant green microalgae plate count at 16-day SRT was 130 CFU/ mL, whereas no LAS degrader/tolerant diatom colonies were observed. Keywords Activated sludge diatoms . Green microalgae . Laundry wastewater . Linear alkylbenzene sulfonate . Micropollutants 1 Introduction Laundry wastewater (LWW) is an important component of grey wastewater. Household greywater can be cate- gorized as wastewater from washbasin, bathroom, and shower (47%), kitchen sink and dishwasher (27%), and laundry and washing machine (26%) (Ghaitidak and Yadav 2013). LWW is the wastewater that comes out of the laundry process and has a high concentration of chemicals from soap water (such as sodium, phospho- rus, surfactants, and nitrogen), bleaches, oils, paints, solvents, and non-biodegradable fibers from clothing (Morel and Diener 2006). Surfactant (mainly anionic) is one of the major constituents of the laundry wastewa- ter. Known environmental effects due to the accumula- tion of these detergent compounds include lowering of the surface tension of the water, a decrease in the Water Air Soil Pollut (2020) 231:374 https://doi.org/10.1007/s11270-020-04749-x A. Pandey : K. Katam : D. Bhattacharyya (*) Department of Civil Engineering, Indian Institute of Technology Hyderabad, Kandi, Telangana 502285, India e-mail: debrajb@iith.ac.in P. Joseph Agilent Technologies India Pvt. Ltd., Whitefield, Bengaluru 560048, India S. Soda : T. Shimizu Department of Environmental Systems Engineering, Ritsumeikan University, Shiga 5258577, Japan