Recent Patents on Biotechnology - Volume 11, Issue 3, 2017

Background: Synthesis and modification of cost-effective sorbents for removing heavy metals from water resources is an area of significance. It had been reported that materials with biological origins, such as agricultural and animal waste, are excellent alternatives to conventional adsorbents due to their higher affinity, capacity and selectivity towards metal ions. These properties of biomaterials help to reduce or detoxify metal ions concentration in contaminated water to acceptable regulatory standards. Objective: Synthesis of novel, efficient, cost effective, eco-friendly biomaterials for heavy metal adsorption from water is still an area of challenge. Method: In this comprehensive review, acompilation of patents as well as published articles is carried out to outline the properties of different biomaterials based on their precursors along withdetailed description of biomaterial morphology and various surface modification approaches. Results: A detailed study of the performance of adsorbents and the role of physical and chemical modification in terms of enhancing their potential for metal adsorption from water is compiled here. The factors affecting adsorption behavior i.e., capacity and affinity of e biomaterials is also compiled. Conclusion: This paper presents a concise review of reported studies on the synthesis and modification of biomaterials, their use for heavy metal removal from waters and future prospects of this technology.

Background: The global industrialization is fulfilling the demands of modern population at the cost of environmental exposure to various contaminants including heavy metals. These heavy metals affect water and soil quality. Moreover, these enter into the food chain and exhibit their lethal effects on the human health even when present at slightly higher concentration than required for normal metabolism. To the worst of their part, the heavy metals may become carcinogenic. Henceforth, the efficient removal of heavy metals is the demand of sustainable development. Remedy: Bioremediation is the ‘green’ imperative technique for the heavy metal removal without creating secondary metabolites in the ecosystem. The metabolic potential of several bacterial, algal, fungal as well as plant species has the efficiency to exterminate the heavy metals from the contaminated sites. Different strategies like bioaccumulation, biosorption, biotransformation, rhizofilteration, bioextraction and volatilization are employed for removal of heavy metals by the biological species. Bioremediation approach is presenting a splendid alternate for conventional expensive and inefficient methods for the heavy metal removal. Conclusion: The patents granted on the bioremediation of toxic heavy metals are summarized in the present manuscript which supported the applicability of bioremediation technique at commercial scale. However, the implementation of the present information and advanced research are mandatory to further explore the concealed potential of biological species to resume the originality of the environment.

Background: Heavy metal pollution in the environmental samples like soil, water and runoff water is a worldwide problem. Such contamination of environmental matrices by the heavy metals accumulates due to various activities involving human driven sources and industries, although agriculture and sewage disposal are the largest source for the heavy metal contamination. Disposal of heavy metals or waste products containing heavy metals in the environment postures a trivial threat to public safety and health. Heavy metals are persistence and they can also cause biomagnifications and accumulate in food chain. Method: Microbial bioremediation of heavy metal is emerging as an effective technique. Microbial bioremediation is a highly efficient environmental friendly procedure which also reduces the cost of cleanup process associated with heavy metal contamination. New methods for removal of heavy metals from the environmental samples are under development and most recent advancements have been made in exploring the knowledge of metal-microbes interactions and its use for heavy metal remediation. Conclusion: This review paper will focus on the microbial bioremediation process and highlight some of the newly developed patented methods for microbial bioremediation of the heavy metals from the environmental samples using microbial populations.

Background: Patents reveal that heavy metals are natural constituents of the earth's crust, but some heavy metals like cadmium, lead, mercury, arsenic etc. are injurious to living organisms at higher concentration. Nowadays, anthropogenic activities have altered geochemical cycles and biochemical balance of heavy metals. Biomolecules are used nowadays for removal of heavy metals compared to other synthetic biosorbents due to their environmental friendly nature and cost effectiveness. Objective: The goal of this work is to identify the role of biomolecules like polysaccharides, polypeptides, natural compounds containing aromatic acid etc. for heavy metal removal by bio sorption. Discussion: It has been observed that efficiency of biomolecules can be increased by functionalization e.g. cellulose functionalization with EDTA, chitosan with sulphur groups, alginate with carboxyl/ hydroxyl group etc. It was found that the porous structure of aerogel beads improves both sorption and kinetic properties of the material. Out of polypeptides metallothionein has been widely used for removal of heavy metal up to 88% from seawater after a single centrifugation. Conclusion: These cost effective functionalized biomolecules are significantly used for remediation of heavy metals by immobilizing these biomolecules onto materials.

Background: Non-degradable and persistent nature of Cadmium (Cd) poses high toxicity to human, plants and animals. Several industrial processes generated wastes are the main anthropogenic pathway through which Cd enters into the environment. Although, World Health Organization (WHO) has set the limit of Cd in drinking water is 0.005 mg L-1, the industrial activities release much higher concentrations of metal ions to the water stream than the prescribed limits, which leads to the increasing health hazards and environmental pollution. Objective: To address this issue, one of the major applicable solutions is the treatment or purification of contaminated water and effluents. The implantation of wastewater treatment systems aims to minimize environmental impacts, but ultimately generates waste materials, such as sewage sludge, which must be properly recycled. Method: In this review, we focus on the research efforts being made towards the removal of Cd (II) from waste waters using biological means with a special emphasis on the microorganism and agricultural based biosorbents. Results: Mechanistic pathway towards removal of Cd (II) ions from the wastewater, efficiency of the adsorbents and the factors affecting the process have been studied with specific examples. Also the recent patents related to this area have been taken into considerations to understand applicability of microorganism and agricultural based biosorbents. Conclusion: This overview presents various scientific reports towards low-cost microorganism and agricultural based biosorbents for efficient removal of Cd (II) by producing less toxic waste and the future perspective of the process.

Background: In the modern age of globalization and fast industrialization, the environmental matters are fetching more and more annoyance for human being. Patents reveal that heavy metals occur in immobilized form in sediments and as aggregates in nature. However due to the different human activities like ore mining and industrial processes, the natural biogeochemical cycles are disordered instigating amplified deposition of heavy metals in aquatic environments. The most common pollution causing heavy metals are considered to be the mercury, arsenic, lead, copper, silver, cadmium. Objective: The goal of this work is to identify the biological action of heavy metal-contaminated water and sediments which can be categorized into bioaccumulation, biosorption, oxidation/ reduction, leaching, degradation, and phytoremediation. Discussion: Among the various biological methods for decontamination of heavy metals from water, biosorption is known to be the most affordable, economical and efficient option for the management of capacious water bodies encompassing low concentrations of heavy metals. However, the physicochemical properties of the aquatic bodies that would extremely affect the performances of biosorbents should be prudently measured. The precipitation is efficient in decontamination/removal of relatively high concentrations of metals in water. The bioleaching of searched sediments in regulated systems is a speedy process as compared with phytoremediation. Conclusion: In order to decontaminate the heavy metals from water, biological methods are very proficient and useful. These methods can be very efficient in cleaning up environment.