An antifouling polyether sulphone (PES) microfiltration membrane was developed by physical blending of TiO2 nanoparticle for membrane bioreactor (MBR) treating tannery wastewater. Incorporation of anti-fouling materials into the polymer by physical blending and composite PES membranes were synthesized using TiO2 nanoparticle and the membranes were made by Non-Induced Phase Inversion Method (NIPS). The membrane morphology was studied using scanning electron microscopy (SEM) and the stability of the membranes was measured by calculating the tensile strength. From the results of contact angle measurements, the hydrophilicity of the membranes was found to increase with the PES/ 4% TiO2. From the fouling rate analysis, TiO2 nanoparticle incorporated membrane PES/ TiO2 has a higher antibiofouling effect. The antimicrobial properties of TiO2 guaranteed an anti-bio-fouling effect thus by preventing the microbial growth in the membrane. The percentage of COD removal was found to be 89% and the complete removal of suspended solids has been observed.

Microplastics have become so pervasive that they seem to be present all around us due to the significant environmental threat they pose. Microplastic pollutants have become an issue as global plastic manufacturing has increased. Microplastics are plastic wastes with particulates less than 5 mm in size that are absorbed by sediment, water, the atmosphere, and living beings before affecting health. Moreover, there is a shortage of knowledge on the distribution, sources, toxic effects, analytical techniques, and removal technologies of microplastics. This review examines the distribution and global abundance of microplastics in aquatic and terrestrial environments, analytical methods, remediation technologies, and health risks. The following are included in this review article: (1) sampling, extraction, and analysis techniques for microplastics in sediment, water, and salt; (2) the source, global distribution, and concentration of microplastics; (3) toxicity and consequences of microplastics on human health; and (4) several methods for removing microplastics, grouped into three categories: engineered, biopolymer, and bioengineered approaches. The worldwide distribution, identification, toxic effects, and remediation technology of microplastics will benefit greatly from this review.

A laboratory-scale membrane bioreactor (MBR) has been developed for textile dyeing wastewater treatment using fine-tuned polyvinilidinedifluoride (PVDF) composite microfiltration membrane combined with ozonation. These composite membranes were prepared by blending PVDF with Polyetherimide (PEI) and tungsten oxide via phase inversion method. The composite membrane characterizations such as morphology, water uptake, surface roughness, hydrophilicity and porosity were investigated. Contact angle measurements indicated that the hydrophilic property of the PVDF/PEI composite membranes have been increased by increasing the PEI concentration in the casting solution. The membrane modules were fabricated and used for the lab scale reactor, having working volume of 20 L. The membrane performance was evaluated by filtering pure water and real textile dyeing wastewater with the hydraulic retention time of 10 h. The dark coloured real combined effluent from the textile dyeing industry has been used for carrying out the treatment systems. The optimized ozone of 250 mg/L has been given as the pre-treatment to MBR. The filtration experiments have been carried out for 15 days continuously to obtain the membrane flux. Pure water flux values have been found to increase with the modified membranes from 19 to 21 LMH. The overall flux recovery ratio has been improved with the fine-tuned membranes. Total suspended solids were removed completely after this filtration. The overall COD and colour removal efficiency achieved were 92% and 90%.

Microplastic debris is found all around us, from the food we eat to the water we drink. They primarily originate from macroplastic waste, which breaks down into tiny fragments. In this study, lakeshore sediments and lake water have been identified, characterized, and quantified to investigate the distribution of (MPs) particles. From 44 lakes, the lakeshore sediment and lake water samples have been collected. Fourier-transform infrared spectroscopy and a Leica stereo-microscope were used to identify and visually count microplastic particles. According to the findings, 25 particles in 5 g of dry sediments (d. s.) and 57 particles in 1 l of microplastics have been found on average. At all the sampling locations, microplastics with a size of 1 mm-500 & mu;m were the most prevalent. Based on the FT-IR results, it was found that plastic polymers such as nylon, PE, PS, PVC, PETE, PC, PMMA, PU, and PP were present in lakeshore sediment and water samples. From the present research findings, it is found that the lake water and shore sediments of the study region are polluted by the presence of microplastics of various sizes, shapes, and types, which may pose a risk to the lake ecosystem. From the spatial variation map of lake water and shore sediments, it has been revealed that water supply lakes contains high concentration of MPs. The presence of MPs particles can be lifetime cancer risk among the children and adults on consumption of lake water. This study provides the information on the characteristics, quantifi-cation, and health risk assessment of microplastics in surface water environments.

In recent years, the focus of the wastewater management sector has shifted significantly from conventional treatment methods to resource and nutrient recovery techniques to promote a circular economy. The recovery of nutrients such as nitrogen and phosphorus from wastewater marks a sustainable approach to wastewater management and supports ecological and economic sustainability. This chapter includes a comprehensive overview of existing conventional technologies that are used to recover nutrients from different nutrient-rich wastewater generated from domestic, industrial, and agricultural sources as well as from anaerobic digestate. In addition, various advanced methods, such as chemical processes and biological technologies that are used to recover nutrients are also discussed. Furthermore, a few more unique applications of novel futuristic technologies that are in the budding stage or ready for piloting or commercialization are also included. Finally, future perspectives in terms of possible research directions and breakthroughs of a more economic and efficient alternative approach with minimal carbon footprints are also explored.

A laboratory-scale membrane bioreactor (MBR) has been developed for textile dyeing wastewater treatment using fine-tuned polyvinilidinedifluoride (PVDF) composite microfiltration membrane combined with ozonation. These composite membranes were prepared by blending PVDF with Polyetherimide (PEI) and tungsten oxide via phase inversion method. The membrane performance was evaluated by filtering pure water and real textile dyeing wastewater. The composite membrane characterisations such as morphology, water uptake, surface roughness, hydrophilicity and porosity were investigated. Contact angle measurements indicated that the hydrophilic property of the PVDF/PEI composite membranes have been increased by increasing the PEI concentration in the casting solution. The real wastewater used for the experiments were combined effluent which is dark in colour. Optimised ozonation of 5 hours was used in the pre-treatment prior to MBR. The membrane modules were fabricated as modules and submerged into the reactor, having working volume of 20L. The filtration experiments have been carried out for 15 days continuously to obtain the membrane flux. Pure water flux values have been found to increase with the modified membranes from 19LMH to 21 LMH. The hydraulic retention time of 10 hours was given. Total suspended solids were removed completely after this filtration. The overall COD and colour removal efficiency achieved were 92% and 88%.

Novel Polyetherimide (PEI) composite membrane has been investigated to improve the mechanical and antifouling properties. In this study, the preparation and properties of polyetherimide ultrafiltration polymer membranes with pectin as blending additive and tungsten oxide as anti-bacterial agent was studied. The membrane characteristic and performance were investigated by membrane morphology, hydrophilicity, atomic force microscopy, water uptake, zeta potential, pure water flux and antifouling behaviour using model pollutants such as bovine serum albumin, humic acid and real textile wastewater (MBR permeate). It was clearly seen that the biofouling properties were greatly enhanced due to the addition of metal oxide.

The main objective of the present study is evaluation of groundwater aptness for crops and chromium concentration in vegetables from an industrial (leather tanning) sector of South India using geospatial techniques. Seventy groundwater samples were collected from the open and tube wells during November 2017, February 2018, May 2018 and September 2018 to represent northeast (NE) monsoon (October–December), post-monsoon (winter) (January–February), pre-monsoon (summer) (March–May) and southwest (SW) monsoon (June–September) seasons, respectively. In addition, vegetables were also collected during the above-mentioned seasons from the market to assess the level of chromium content in them. All the groundwater samples were tested in the chemical laboratory using the American Public Health Association norms for various physicochemical parameters, viz. TDS, pH, sodium, potassium, calcium, magnesium, bicarbonate, chloride, sulfate, nitrate, fluoride and chromium. Northeast and southwest monsoon season samples mostly represented ‘high to very high saline’ and ‘low alkaline’ categories of irrigation water. However, post- and pre-monsoon samples represented ‘high to very high saline’ and ‘low to medium alkaline’ categories. ‘High saline and low alkaline’ water could be used for irrigation in all types of soil with less problem of exchangeable sodium. However, ‘very high saline’ water should not be applied for the crops having poor salt tolerance and soils having poor internal drainage. The concentration of chromium in groundwater and vegetables was within the permissible limits for human intake prescribed by the World Health Organization standards.

Effluents from leather tanneries and other small-scale industries have caused groundwater contamination in one of the biggest industrial centers (i.e. Vellore) of south India. This study evaluated quality of 70 different open and tube wells for consumption and health risks by collecting groundwater samples in four different seasons between 2017−2018. We compared physicochemical parameters of the groundwater samples with international drinking water standards (World Health Organization) to know their suitability for human consumption. Piper’s trilinear diagram classified most of them as Ca-Cl and mixed Ca-Mg-Cl types. Inverse Distance Weighted (IDW) spatial interpolation showed the spatial distributions of different groundwater quality parameters. These parameters, including the Water Quality Index (WQI), indicated that most of the samples collected during the non-rainfall seasons (post-NE monsoon: 82.8 %; pre-SW monsoon: 78.6 %) were ‘poor’ for consumption. However, the qualities of 40–44.3 % of samples collected during both the rainfall seasons (NE and SW monsoon) were “good”. We evaluated non-carcinogenic health risks for children and adults from consumption of the nitrate-rich groundwater by estimating the Hazard Quotient (HQ). Our results did not suggest any health risk for children and adults during both the rainfall seasons. In the non-rainfall seasons, about 59–63 % of samples posed health risk to children and 37–39 % caused possible health risk to the adult population.

In the present study, impact of precipitation disparity on groundwater level fluctuation was carried out in Vellore district, Tamil Nadu, India, using geospatial techniques. There are five rain gauge stations in the study area in which three rain gauge stations, namely Alangayam, Jolarpettai and Pernampet, receive more precipitation when compared with the average annual precipitation of Tamil Nadu state (920 mm). The other two stations, namely Madanur and Natrampalli, receive less than 920 mm of precipitation annually. The overall average annual precipitation of the study area is 913.6 mm. More than 100 mm precipitation is received in all the five rain gauge stations during southwest (SW) and northeast (NE) monsoon seasons. The maximum monthly precipitation is usually recorded during the month of November and the minimum precipitation is recorded during June. The post-monsoon precipitation is around 10.8 mm, which is almost negligible in the study area. The contribution of precipitation by various seasons is in the following sequence: Southwest monsoon > Northeast monsoon > Pre-monsoon > Post-monsoon. The spatial disparity study indicates that the intensity of average annual, pre-monsoon and post-monsoon precipitations increase towards west in the study area. The intensity of precipitation is more in the northern part during SW monsoon season, whereas the intensity is more in the southern part during NE monsoon season. The spatial disparity analysis of groundwater fluctuation shows that the depth of groundwater (below ground level) increases towards west during all the monsoon seasons. The minimum, mean and maximum depths of occurrence of groundwater in this region are, respectively, 1.6, 9.6 and 21.15 m. Declining trend in the regional groundwater level is observed from December to June because of less precipitation during non-monsoon season. However, the monsoon (both SW and NE monsoon) precipitation recharges the groundwater from June to December to reach the maximum in the month of December.

The novel FeWO4/BiPO4 heterojunction generates an inner electric field to promote electron–hole separation efficiency and is a proficient photocatalyst.

Samarium doped BiPO4 photocatalyst was synthesized by a simple hydrothermal method. The structural, morphological and optical properties were investigated using XRD, FTIR, SEM, EDS, and UV-DRS techniques. The XRD analysis confirms pure hexagonal and well crystallized structure of the synthesized photocatalyst and average crystallite size of the doped catalyst was 23.28 nm. Fourier transform infrared (FTIR) spectra show stretching and bending vibrations of PO4 group corresponding to hexagonal structure. SEM images showed that the samples have spherical like morphology and EDS confirms the presence of samarium metal. The photocatalytic activity of Sm3+-BiPO4 samples were evaluated for the degradation of methylene blue dye in aqueous solution under UV light irradiation. The color removal efficiency of Sm3+-BiPO4 and pure BiPO4 was 97% and 66% after 50 min. irradiation, respectively. The enhanced photocatalytic activity could be mainly attributed to the charge separation. Sm3+ doping improved the photocatalytic activity of BiPO4 in degrading methylene blue.

A novel submerged membrane bioreactor integrated with ozonation and photocatalysis has been developed to treat the real textile wastewater and study the fouling behaviour. This study evaluates the performance efficiency in pilot-scale for the three reactors such as membrane bioreactor, ozonised membrane bioreactor and further clubbed with photocatalysis. The membrane filtration consists of polyvinilidine difluoride hollow fibre membrane module having pore size 0.1 μm. Tungsten oxide, a visible photocatalyst was made into spongy alginate beads and used in photocatalytic reactor. The photocatalyst dose has been optimised as 500 mg/L. About 10% membrane filterability ratio has been achieved by integrating ozone with MBR with the maximal ozone dosage of 5 g/h. It showed better removal efficiency in colour and chemical oxygen demand of 94% and 93% respectively. The biodegradability efficiency also was enhanced from 0.2 to 0.4 with optimised ozone dosage (5 g/h). The study on reversible and irreversible fouling has been done to understand the fouling nature. The important analysis such as microbial community and scanning electron microscopy analysis were done to study the biofouling and extent of fouling after filtration. The treatability studies implemented for textile wastewater showed that integrated MBR systems are suitable in meeting the discharge norms prescribed by the Indian statutory body in terms of chemical oxygen demand, colour and total suspended solids.

This study reports a green and facile hydrothermal method to synthesis α-Fe 2 O 3 /BiPO 4 composite and was used for photocatalytic application under visible light irradiation. The synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectrum (UV–Vis DRS), Fourier transform infrared (FT-IR) spectrum, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmet–Teller (BET) analysis and Photoluminescence (PL), which confirmed the formation of the composite. XRD analysis indicated that all the prepared samples present in pure hexagonal structure without Fe 2 O 3 phases. The photocatalytic studies on methylene blue (MB) and ciprofloxacin (CIP) were evaluated under visible light irradiation and the α-Fe 2 O 3 /BiPO 4 composite exhibited superior photocatalytic activity compared to the BiPO 4 . The results of PL studies substantiated that the enhancement of photocatalytic activity could be mainly attributed to the interaction of α-Fe 2 O 3 and BiPO 4 in the composite during photocatalysis which effectively improve electron–hole separation. The recyclability experiment corroborated the stability of α-Fe 2 O 3 /BiPO 4 composite. Finally, the composite was converted into beads using calcium alginate, a non toxic biopolymer for easy separation of the catalyst from the reaction medium, which also showed equally good results.