Residual pollutants in treated pulp paper mill wastewater and their phytotoxicity and cytotoxicity in Allium cepa

Discharged pulp and paper mill wastewater (PPMW) were collected near M/s K. R. pulp and papers Limited, Shahjahanpur, India. Chemical analysis of the wastewater showed high BOD (3653-4180 mg L-1) and COD (17890-19100 mg L-1) values from two different sampling sites. The levels of total phenol were in the range of 389-432 mg L-1, nitrogen (125-234 mg L-1), sulfate (1926-2098 mg L-1), chloride (3.12-5.43 mg L-1) and lignin (38950-39000 mg L-1) along with various heavy metals (Fe, 87-79; Zn, 34-22; Cu, 3.28-2.57; Cd, 1.90- 0.36; Ni, 6-5, and Pb, 41.23-36.54 mg L-1); these were above the permissible limit as recommended by the CPCB and the USEPA. The BOD/COD ratio was <0.2 which indicated very low biodegradability of the organic matters present in the effluent. The organometallic complex generated from the pulp and paper industry persists in the environment and might toxic to the aquatic organism. The organic polymers, lignin, metals and ions present in the PPMW were characterized using SEM, EDAX, FTIR and UV-Vis spectroscopy. The major pollutants detected included: nonacosane, heptacosane, octadecanoic acid, hexadecane, and 6-benzamide- 3- [2- [1-(phenylmethyl)-4-piperidinyl] ethyl] -1, 2-benzisoxazole; as well as a group of plant fatty acids classified as EDCs, and mutagenic pollutants. The cytotoxic and androgenic properties of these complex organics were examined using the seed germination test with Phaseolus mungo and cytotoxicity test with Allium cepa. Results showed that at >20% concentration of PPMW, α-amylase production was inhibited and chromosomal segregation at metaphase and anaphase during cell division was disturbed which resulted in c-mitosis, sticky chromosomes, and laggard chromosomes. In addition, SEM of the root of A. cepa showed fissures and fractured tissues of the root cap, probably due to the inhibition of auxins that were responsible for root cap formation. The findings indicated A. cepa as a good test model for examining the DNA damage and cytotoxicity by PPMW; and the discharged effluent should be treated at the tertiary stage for environmental protection.

This is a post-peer-review, pre-copyedit version of an article published in Environmental Geochemistry and Health. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10653-020-00730-z