Ecotoxicological Risk Assessment of Paper Mill Effluent Waste Water

Aquatic ecosystem has been reported to be the universal sufferer of pollution caused by direct exposure of industrial discharges which causes severe genotoxic damages to aquatic flora and fauna. Researchers have found that fish have been extensively harmed by such exposure compared to other aquatic fauna. As living organisms directly depend on fish as a food resource, hence the study of mutagenicity induced have been extensively important not only for safety of aquatic organisms but also for safety of other living organisms too. Micronucleus (MN) assay has been continuously used in the evaluation of DNA damage. Mutagenic and genotoxic studies employed this methodology to evaluate possible carcinogenic risk due to exposure to harmful xenobiotics in including aquatic organisms. The aim of this study was to monitor the level of genotoxicity induced in fishes due to exposure to local paper mill effluent by using micronucleus assay as a biomarker. Fish were exposed to different concentrations of PME as 10%, 25% and 50%. Variation of body weight, survivality rate and percentage of micronucleated PCEs were analyzed. One-way anova was performed and data were expressed as Mean± S.E. Consecutive dose dependent and time dependent increase of toxicity was recorded in PME compared to negative and positive control (Mitomycin C). Our study supported the carcinogenic and chromosomal damage induced in aquatic organisms specially in fishes due to direct exposure of industrial discharges; also, the importance of MN test as an effective indicator for testing genotoxicity in fishes was confirmed.

Degradation of lignin by Bacillus altitudinis SL7 isolated from pulp and paper mill effluent

Lignin is a major by-product of pulp and paper industries, which is resistant to depolymerization due to its heterogeneous structure. Degradation of lignin can be achieved by the use of potential lignin-degrading bacteria. The current study was designed to evaluate the degradation efficiency of newly isolated Bacillus altitudinis SL7 from pulp and paper mill effluent. The degradation efficiency of B. altitudinis SL7 was determined by color reduction, r lignin contents, and ligninolytic activity from degradation medium supplemented with alkali lignin (3 g/L). B. altitudinis SL7 reduced color and lignin contents by 26 and 44%, respectively, on 5th day of the incubation, as evident from the maximum laccase activity. Optimum degradation was observed at 40 °C and pH 8.0. FT-IR spectroscopy and GC-MS analysis confirmed lignin degradation by emergence of the new peaks and identification of low molecular weight compounds in treated samples. The identified compounds such as vanillin, 2-methyoxyhenol, 3-methyl phenol, oxalic acid and ferulic acid suggested the degradation of coniferyl and sinapyl groups of lignin. Degradation efficiency of B. altitudinis SL7 towards high lignin concentration under alkaline pH indicated the potential application of this isolate in biological treatment of the lignin-containing effluents.

Biosynthesis of Zinc Oxide Nanoparticles Using Leaf Extract of Prosopis juliflora as Potential Photocatalyst for the Treatment of Paper Mill Effluent

This paper reports on the manufacture of ZnO nanoparticles (ZnO NPs) from Prosopis juliflora leaf extracts. Various methods of characterization were used, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and transmission electron microscope TEM. ZnO NPs has a hexagonal wurtzite structure with a preferred orientation of 101 planes, according to XRD. The functional groups found in ZnO NPs isolated from leaves are responsible for the FT-IR peaks that correspond to them. The morphology of the produced nanoparticles is a sphere-like form, as shown in the SEM pictures. TEM examination revealed ZnO NPs with a size of 50–55 nm. These ZnO NPs were used to remediate pollutants in paper mill effluents, and they were able to remove 86% of the organic pollutants from the sample at 0.05 mg/L dose and reduce 89% of the organic pollutants during a 5-h reflex time. Meanwhile, for the photocatalysis of paper mill effluents, it has been noted that COD was removed by 74.30%, 63.23%, and 57.96% for the first, second, and third cycles, respectively.

Application of sequencing batch biofilm reactor (SBBR) to recycled paper mill effluent treatment

Paper mill effluent has been characterized as recalcitrant because of containing lignin and its derivatives. Since biofilm system exhibits a notable potential for the removal of recalcitrant contaminants, a sequencing batch biofilm reactor (SBBR) was employed to treat coagulated recycled paper mill effluent in this study. The results indicated that the SBBR removed 91.3 % of chemical oxygen demand (COD), whilst total suspended solid (TSS) and color removal reached 83.1 % and 71.0 %, respectively. The microbial analysis suggested that three typical heterotrophic phyla, Proteobacteria, Bacteroidetes and Acidobacteria are dominant bacteria and reflected the removal of recalcitrant contaminants. The COD removal rate of SBBR is evidently superior to conventional activated sludge process due to high sludge concentration as well as long sludge retention time (SRT). Whilst the problem of sludge bulking can be successfully avoided, the blockage of reactor caused by TSS accumulation and microbial growth deserve further investigation.

Effect of Paper Mill Effluent on Lipid Profile of Freshwater Snake Headed Fish, Channa punctatus (Bloch, 1793)

Industrial effluents reaching the aquatic ecosystem through various routes like run-off, leaching, and direct discharge from factories are major causes of environmental pollution. These were reported to have a negative metabolic impact on different non-target aquatic organisms. Fish is a close inhabitant of the aquatic environment, serves as a useful model for assessing the effect of chemicals mixed in the aquatic environment. Channa punctatus Bloch (Actinopterygii: Channidae), one of the most common edible fish, if exposed to industrial effluents containing harmful substances, maybe a serious threat to human health. In the present study, an attempt was made to understand the effect of sublethal concentrations of paper mill effluent on lipid profiles of Channa punctatus after exposure to 96 hours. A significant increase was observed in total serum lipid, cholesterol, and phospholipid with decreased triglyceride levels. A significant increase was observed in the cholesterol and triglycerides levels, whereas total lipids and phospholipid levels showed a marked decline in the liver. Thus present study concludes that the estimation of the lipids profile of fish will certainly detect early signs of stress physiology concerning their habitat.

Performance of Modified Anaerobic Hybrid Baffled (MAHB) bioreactor treating recycled paper mill effluent: Effects of organic loading rates

The performance of modified anaerobic hybrid baffled (MAHB) bioreactor treating recycled paper mill effluent (RPME) was investigated at various organic loading rates (OLR) of 1, 2, 3 and 4 g COD/ L.day. The bioreactor was operated continuously at constant hydraulic retention time (HRT) of a day without effluent recycled and chemicals adjustment/addition. Throughout 70 days of operation, a maximum removal efficiency up to 97% of chemical oxygen demand (COD) and 98% of volatile fatty acid, biogas production of 12.51 L/day equivalent to methane (CH4) yield of 0.108L CH4/ g COD and a stable pH system between 6.6 to 7.2 were achieved. Additionally, alkalinity of the bioreactor system shows a stable profile that indicates the whole system was well buffered with a quit high degradation of volatile solid (VS) up to 18%. These results indicated that MAHB bioreactor has been successfully treated RPME at various OLR.

Silica Removal from a Paper Mill Effluent by Adsorption on Pseudoboehmite and γ-Al2O3

Effluent reuse is a common practice for sustainable industrial water use. Salt removal is usually carried out by a combination of membrane processes with a final reverse osmosis (RO). However, the presence of silica limits the RO efficiency due to its high scaling potential and the difficulty of cleaning the fouled membranes. Silica adsorption has many advantages compared to coagulation and precipitation at high pHs: pH adjustment is not necessary, the conductivity of treated waters is not increased, and there is no sludge generation. Therefore, this study investigates the feasibility of using pseudoboehmite and its calcination product (γ-Al2O3) for silica adsorption from a paper mill effluent. The effect of sorbent dosage, pH, and temperature, including both equilibrium and kinetics studies, were studied. γ-Al2O3 was clearly more efficient than pseudoboehmite, with optimal dosages around 2.5–5 g/L vs. 7.5–15 g/L. The optimum pH is around 8.5–10, which fits well with the initial pH of the effluent. The kinetics of silica adsorption is fast, especially at high dosages and temperatures: 80–90% of the removable silica is removed in 1 h. At these conditions, silica removal is around 75–85% (<50 mg/L SiO2 in the treated water).