LAUSR

Abstract Paper mill wastewater is a complex mixture of different organometallic pollutants with alkaline pH and toxicity to aquatic organisms. This study investigates major physicochemical parameters such as BOD (814.0 ±  2.84), COD (2289.0 ±  3.54), TDS (4128.0 ±  5.21), dissolved solid (3520.0 ±  4.85), suspended solids (608.0 ±  1.53), lignin (628 ±  2.24) and heavy metals along with organometallic pollutants from paper mill wastewater detected by gas chromatography and mass spectrophotometer technique. The organometallic pollutants such as decane, 2,9-dimethyl, eicosane, 2-bromotetradecane, 1,2-dihydro-1,4-diphenylphthalazine, benzene acetic acid, 4-[(trimethylsilyl)oxy]-, trimethylsilyl ester, and docosane were detected via. gas chromatography and mass spectrophotometry (GC–MS). These pollutants are highly toxic and cause significant adverse effects on aquatic organisms. The toxic effects of organometallic pollutants were tested on Heteropneustes fossilis (Stinging catfish) and Tubifex-tubifex (sludge worm) using different concentrations of wastewater (25%, 50%, 75%, and 100%). Due to wastewater exposure Heteropneustes fossilis, toxic effects were observed, showing notable changes in the secondary lamellae (SL); primary lamellae (PL); mucous cell (MC); epithelial cell (EC); chloride cell (CHC). In Tubifex tubifex, minimum toxic effects were noted at the concentration of less than 25% up to 24 h of exposure and maximum at 48 h of exposure at 50% of the wastewater concentration. After 24 h wastewater exposure, the hemoglobin content was decreased, the body’s rear part became white, and body disintegration was observed in worms. In conclusion, the present study investigates that paper mill wastewater is toxic to the aquatic ecosystem and must be treated and assessed before discharge.