The controversy related to the environment pollution is increasing in human life and in the eco-system. Especially, the water pollution is growing rapidly due to the wastewater discharge from the industries. The only way to find the new water resource is the reuse of treated wastewater. Several remediation technologies are available which provides a convenience to reuse the reclaimed wastewater. Heavy metals like Zn, Cu, Pb, Ni, Cd, Hg, etc. contributes various environmental problems based on their toxicity. These toxic metals are exposed to human and environment, the accumulation of ions takes place which causes serious health and environmental hazards. Hence, it is a major concern in the environment. Due to this concern, the significance of developing technology for removing heavy metals has been increased. This paper contributes the outline of new literature with two objectives. First, it provides the sketch about treatment technologies followed by their heavy metal capture capacity from industrial effluent. The treatment performance, their remediation capacity and probable environmental and health impacts were deliberated in this review article. Conclusively, this review paper furnishes the information about the important methods incorporated in lab scale studies which are required to identify the feasible and convenient wastewater treatment. Moreover, attempts have been made to confer the emphasis on sequestration of heavy metals from industrial effluent and establish the scientific background for reducing the discharge of heavy metals into the environment.

Efficient techniques for the removal of toxic heavy metals from aquatic environment: A review

Antibiotics, disinfectants and bacteria resistant to them have been detected in environmental compartments such as waste water, surface water, ground water, sediments and soils. Antibiotics are released into the environment after their use in medicine, veterinary medicine and their employment as growth promoters in animal husbandry, fish farming and other fields. There is increasing concern about the growing resistance of pathogenic bacteria in the environment, and their ecotoxic effects. Increasingly, antibiotic resistance is seen as an ecological problem. This includes both the ecology of resistance genes and that of the resistant bacteria themselves. Little is known about the effects of subinhibitory concentrations of antibiotics and disinfectants on environmental bacteria, especially with respect to resistance. According to the present state of our knowledge, the impact on the frequency of resistance transfer by antibacterials present in the environment is questionable. The input of resistant bacteria into the environment seems to be an important source of resistance in the environment. The possible impact of resistant bacteria on the environment is not yet known. Further research into these issues is warranted.

Resistance in the Environment

A review on heavy metal pollution, toxicity and remedial measures: Current trends and future perspectives

Heavy metals like arsenic, copper, cadmium, chromium, nickel, zinc, lead, and mercury are major pollutants of fresh water reservoirs because of their toxic, non-biodegradable, and persistent nature. The industrial growth is the major source of heavy metals introducing such pollutants into different segments of the environment including air, water, soil, and biosphere. Heavy metals are easily absorbed by fishes and vegetables due to their high solubility in the aquatic environments. Hence, they may accumulate in the human body by means of the food chain. Various methods have been developed and used for water and wastewater treatment to decrease heavy metal concentrations. These technologies include membrane filtration, ion-exchange, adsorption, chemical precipitation, nanotechnology treatments, electrochemical and advanced oxidation processes. In this review, the methods as well as their mechanisms and efficiency are discussed.

Removal of Heavy Metals from Industrial Wastewaters: A Review

Graphene and other two-dimensional materials offer a new approach to controlling mass transport at the nanoscale. These materials can sustain nanoscale pores in their rigid lattices and due to their minimum possible material thickness, high mechanical strength and chemical robustness, they could be used to address persistent challenges in membrane separations. Here we discuss theoretical and experimental developments in the emerging field of nanoporous atomically thin membranes, focusing on the fundamental mechanisms of gas- and liquid-phase transport, membrane fabrication techniques and advances towards practical application. We highlight potential functional characteristics of the membranes and discuss applications where they are expected to offer advantages. Finally, we outline the major scientific questions and technological challenges that need to be addressed to bridge the gap from theoretical simulations and proof-of-concept experiments to real-world applications.

Fundamental transport mechanisms, fabrication and potential applications of nanoporous atomically thin membranes

Nanofiltration membranes review: Recent advances and future prospects

New generation nanomaterials for water desalination: A review

Hydrogel is a promising adsorbent for heavy metal removal. In order to conserve the environment by avoiding the hydrogel disposal problem after the adsorption process, this research work was carried out to explore the feasibility in synthesizing biodegradable cellulose hydrogel and cellulose/gelatin composite hydrogel. The effect of cross-linker volume percent and gelatin weight percent towards the adsorption capacity of hydrogels were investigated. Cellulose hydrogel with the lowest cross-linker volume percent, H6 (6 v/v%) has the greatest swelling ability (4650%), highest biodegradability rate (79.5%), and highest adsorption capacity (28.4 mg/g) compared to other cellulose hydrogels. Less compact structure of H6 has the potential to facilitate the movement of Cu2+ ions into the hydrogel network, increased the accessibility of the Cu2+ ions onto the active sites of the hydrogel, and thus enhanced its characteristics and adsorption performance. The addition of gelatin into cellulose hydrogel network has further improved the swelling ability and adsorption capacity of cellulose/gelatin composite hydrogel attributed to the presence of amine group from gelatin which has stronger affinity towards water absorption and presented stronger binding propensity towards Cu2+ ions. The experiment data was fitted better to the Freundlich model, indicating the occurrence of multilayer adsorption. This success of this research study has confirmed the potential application of cellulose hydrogel and cellulose/gelatin composite hydrogel as a more sustainable and environmental-friendly adsorbent for the removal of heavy metal from wastewater.

Synthesis of cellulose hydrogel for copper (II) ions adsorption

In this study, novel polysulfone-Fe 3 O 4 /GO mixed-matrix membrane was prepared by embedding the iron-decorated graphene oxide (Fe 3 O 4 /GO) into polysulfone (PSf) polymer. First, graphene oxide (GO) nanoplates were synthesized using natural graphite powder according to the Hummers method. Fe 3 O 4 /GO was then prepared by mixing both GO and Fe 3 O 4 in the presence of ammonia hydroxide (NH 4 OH) according to co-precipitation method. A series of test, such as X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) were performed to characterize the produced Fe 3 O 4 /GO nano-hybrid. Mixed-matrix membrane was fabricated by casting the pre-mix PSf-Fe 3 O 4 /GO polymer solution mixture using phase inversion method. The performance of both neat PSf membrane and novel polysulfone-Fe 3 O 4 /GO mixed-matrix membrane were evaluated by measuring the membrane permeate flux and humic acid rejection. Experiment demonstrated that the novel polysulfone-Fe 3 O 4 /GO mixed-matrix membrane was having 3 times higher permeate flux than the neat PSf membrane despite the drop in humic acid rejection from 89 ± 2% to 84 ± 2%. However, polysulfone-Fe 3 O 4 /GO mixed-matrix membrane permeability was increased with the compensation of decreasing retention capacity due to pore size enlargement, higher porosity as well as higher hydrophilicity.

Preparation of novel polysulfone-Fe3O4/GO mixed-matrix membrane for humic acid rejection

Nanofiltration (NF) membrane has been applied for the treatment of wastewater owing to its unique features such as higher selectivity towards divalent/polyvalent ions while allowing permeation for monovalent ions and small molecules of less than 100 Da. Thus, the use of NF in wastewater treatment is promising for water recycling, reuse, and recovery of other valuable products in industrial wastewater treatment. This review highlights the current application of NF for water recycling, reuse, and product recovery within multiple industries such as textile, food, oil and gas, mining, tannery, pharmaceutical as well as pulp and paper industry. The performance of NF either as stand-alone or integrated with other processes for improving the overall treatment efficiency and minimizing membrane issues is discussed. Finally, future perspectives for NF applications in industrial wastewater treatment for water recycling, reuse, and product recovery are discussed. • Water recycling and reuse is becoming very important for sustainable development. • Membrane technology can play very important role in water recycling and reuse. • Apart from water recovery, valuable products can also be recovered. • Nanofiltration (NF) membrane is unique and provide opportunities for reuse and recovery. • Integrated technologies with NF membrane can improve efficiency and higher performance. 

Yeit Haan Teow

Papers

Nanofiltration membranes review: Recent advances and future prospects

New generation nanomaterials for water desalination: A review

Synthesis of cellulose hydrogel for copper (II) ions adsorption

Preparation of novel polysulfone-Fe3O4/GO mixed-matrix membrane for humic acid rejection

Nanofiltration membrane processes for water recycling, reuse and product recovery within various industries: A review