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

Photocatalytic degradation of organic pollutants using TiO2-based photocatalysts: A review

The global use of petroleum hydrocarbons for energy and raw materials in various applications has increased with extensive release of a wide variety of contaminants into the environment, affecting soil, surface water and groundwater. The effect results to numerous health, ecological and environmental issues. However, treatment of contamination and pollution caused by petroleum hydrocarbons is a huge and laborious work. It involves several in situ or ex situ treatments comprising containment, separation and destruction which include biological, chemical, physico-chemical, thermal and heat, electric and electromagnetic, acoustic and ultrasonic treatment methods. These treatment methods involve several other techniques and strategies as listed in this review. The health risks pose by petroleum hydrocarbon pollution have driven scientists to research, develop and implement risk-based remediation strategies for restoration and reclamation of affected environments. To select the best treatment option for remediation, it is important to comprehend the nature, composition, properties, sources of pollution, type of environment, fate, transport and distribution of the pollutants, mechanism of degradation, interaction and relationships with microorganisms, the intrinsic and extrinsic factors affecting remediation. It helps to evaluate and predict the chemical behaviour of the pollutants with the short and long-term effects and mitigate the effects of pollution and limit exposure to the pollutants. Despite the available remediation options for petroleum hydrocarbon management and removal, sufficient and complete remediation can be implemented by adoption of proper approach derived from risk-based management procedure that can be practical, scientifically defensible, widely adapted, sustainable, non-invasive, eco-friendly and cost-efficient. This paper provides an overview of the various remediation and treatment technologies derived from risk-based approaches that are used for isolation, containment, separation, restoration reclamation and remediation of soil, sediments, surface water and groundwater contaminated by petroleum hydrocarbons and organic compounds.

Remediation of soil and water contaminated with petroleum hydrocarbon: A review

The wastewater reclamation is the need of today's world. Advanced oxidation processes (AOPs) are considered as a good option for removing recalcitrant organic materials in wastewater by oxidation reactions with powerful, non-selective hydroxyl radical (OH•). Ozone alone does not cause complete oxidation of some refractory organic compounds and has a low reaction rate. The ozone is combined with H2O2, UV light, catalyst, ultrasound to enhance the generation of hydroxyl radicals to increase the efficiency of the treatment process. The ozone-based AOPs have been proved to be effective in detoxifying an ample range of industrial effluents containing recalcitrant organics, pharmaceutical products, pesticides, phenols, dyes, etc. Ozone based AOP processes such as O3/UV, O3/H2O2, O3/Fe (II), O3/metal oxide catalyst, O3/activated carbon, O3/ultrasound, O3/Fenton, photocatalytic ozonation were discussed. A review of ozone-based AOP processes as a combination of ozonation with other techniques for the degradation and mineralization of recalcitrant organics present in the industrial/municipal wastewater based on the recently published work were reported.

Recent advances in ozone-based advanced oxidation processes for treatment of wastewater- A review

Organophosphates are one of the major constituent of herbicides, pesticides, insecticides and nerve gas. Azinophos-methyl, chlorpyrifos, diazinon, fonofos and disulfoton are well-known organophosph...

Toxicity, monitoring and biodegradation of organophosphate pesticides: A review

This study has focused on the treatment of real tannery effluent using different advanced oxidation processes in lab and pilot scale studies. Periodic monitoring was conducted for five months to identify the performance at different stages of treatment in the CETP. Monthly monitoring analysis shows that ratio of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were about 0.1–0.25. It was observed that even after physicochemical treatment the sample had a low biodegradability index (BDI). For this reason, more efficient methods of advanced oxidation processes like Fenton, Ozonation have been experimented with primary settling tank (PST) effluent to improve the biodegradation in the successive activated sludge process and secondary settling tank (SST) effluent to remove the residual inorganics. Sample collection and analysis were performed using standard methods of analysis. Pollutant removal efficiency was measured in terms of reduction in COD and Total Organic Carbon (TOC). The purification effect obtained by Advanced Oxidation Processes (AOPs) was better in Ozone when compared to Fenton. A three step process of (coagulation + aeration + O 3 ) resulted in 80–90% reduction of COD. Coagulation, extended aeration followed by ozonation was recognized as the best method of treatment of tannery wastewater. Lab scale and pilot scale studies were done with real tannery wastewater effluents and the economics of the treatment processes were evaluated.

Advanced oxidation processes for the treatment of tannery wastewater

Antibiotics are majorly used in food animals for growth promotion and prophylactic purposes in public health and environment. The aim of this review is mainly to discuss about the antibiotics usage in poultry, livestock and aquaculture sectors, particularly in India, and the identification of antibiotic resistance in animals, their corresponding antibiotic resistance genes (ARGs) (if investigated) and their dissemination among environmental compartments in various parts of the country. It also discusses about the classification and mechanism of action of different antibiotics. It reports the risks, benefits, ARGs development mechanisms from food animals to humans and to the environment. Most of the current studies are done in the medical field on regulating/restricting antibiotic usage and tracking the propagation of ARGs in bacterial samples of sick patients and also report the identification of antibiotics and ARGs in wastewater treatment plant effluents across various countries. This study mainly reviews the evolution and transportation of ARGs in detail for Indian scenario.

K. Sivagami

Papers

Advanced oxidation processes for the treatment of tannery wastewater

Antibiotic usage, residues and resistance genes from food animals to human and environment: An Indian scenario

Treatment of petroleum oil spill sludge using the combined ultrasound and Fenton oxidation process

Chlorpyrifos and Endosulfan degradation studies in an annular slurry photo reactor.

Catalytic pyrolysis of polyoleﬁn and multilayer packaging based waste plastics: A pilot scale study