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.

Water Quality Assessment of Paper Mills Effluent Discharge Areas

The study attempted to assess the water quality around paper mill effluents discharge areas. Several physicochemical parameters and the Canadian Council of Ministers of the Environment (CCME) Water Quality Index (WQI) were considered to determine the pollution level of surface and groundwater in the selected paper mills areas located in Saidpur, Gobindaganj, and Dupchanchia Upazilas of Bangladesh. Physicochemical characterization of the surface water around the paper mills areas showed that the concentration of EC, TSS, BOD5, COD, phenols, NO3−-N, and K+were exceeded the surface water standard, whereas the DO level ranged from 1.63 to 3.5 were found below the Environmental Conservation Rules (ECR), 1997 standard. Besides, the BOD, COD, and Mn ion concentrations of groundwater exceeded the drinking water standard. In most sampling sites, the WQI of the surface water showed ‘marginal’ category, and the groundwater quality showed 'fair' category. The study observed that the toxic effluents discharged from the paper mills caused harm to the aquatic ecosystem.

Endocrine Disruptor Impacts on Fish From Chile: The Influence of Wastewaters

Industrial wastewaters and urban discharges contain complex mixtures of chemicals capable of impacting reproductive performance in freshwater fish, called endocrine-disrupting compounds (EDCs). In Chile, the issue was highlighted by our group beginning over 15 years ago, by analyzing the impacts of pulp and paper mill effluents (PPME) in the Biobio, Itata, and Cruces River basins. All of the rivers studied are important freshwater ecosystems located in the Mediterranean region of Central Chile, each with a unique fish biodiversity. Sequentially, we developed a strategy based on laboratory assays, semicontrolled-field experiments (e.g., caging) and wild fish population assessments to explore the issue of reproductive impacts on both introduced and native fish in Chile. The integration of watershed, field, and laboratory studies was effective at understanding the endocrine responses in Chilean freshwater systems. The studies demonstrated that regardless of the type of treatment, pulp mill effluents can contain compounds capable of impacting endocrine systems. Urban wastewater treatment plant effluents (WWTP) were also investigated using the same integrated strategy. Although not directly compared, PPME and WWTP effluent seem to cause similar estrogenic effects in fish after waterborne exposure, with differing intensities. This body of work underscores the urgent need for further studies on the basic biology of Chilean native fish species, and an improved understanding on reproductive development and variability across Chilean ecosystems. The lack of knowledge of the ontogeny of Chilean fish, especially maturation and sexual development, with an emphasis on associated habitats and landscapes, are impediment factors for their conservation and protection against the threat of EDCs. The assessment of effects on native species in the receiving environment is critical for supporting and designing protective regulations and remediation strategies, and for conserving the unique Chilean fish biodiversity.

Pulp and paper industry wastewater treatment: use of microbes and their enzymes

Pulp and paper industry is coming under one of the most water polluting industries, and generated wastewater is highly toxic in nature. The paper mill requires huge quantity (~50–60 m3 of water to produce one ton of paper) of water, and accordingly huge quantity of chemical contaminated wastewater is discharged. The paper mill effluents have identified 240–250 chemicals in different stages of paper making. Various chemical constituents such as high chemical oxygen demand, biochemical oxygen demand, AOX, chlorinated compounds, color, suspended materials, lignin and their derivatives are released in the wastewater. The present review study is focused on the paper mill processes, wastewater generation and its effective treatment by microorganisms. The biological treatment has been identified as cost-effective and eco-friendly methods for the degradation of xenobiotic compounds for paper mill wastewater. Various studies have been performed so far to investigate the complex nature of wastewater by the application of bacteria, fungi and their enzymes at industrial scale. Therefore, the article discussed the importance of biological method as an effective technique for the degradation of paper mill wastewater.