Amit Dhir

Bio: Amit Dhir is an academic researcher from Thapar University. The author has contributed to research in topics: Diesel fuel & Diesel engine. The author has an hindex of 21, co-authored 80 publications receiving 1110 citations.

Treatment of real pharmaceutical wastewater using combined approach of Fenton applications and aerobic biological treatment

Abstract: The pharmaceutical wastewater of different organic loads i.e. high (HSW) and low strength wastewater (LSW) were collected from the bulk pharmaceutical industry and subjected to different applications of Fenton’s treatment followed by subsequent biological treatment. For both the HSW and LSW, applications of Fenton such as, dark-Fenton (DF), solar driven photo-Fenton (PF) and electro-Fenton (EF) were utilized as pre-treatment technologies to improve the biodegradability and reduce the organic load of wastewater by combine oxidation and coagulation. The operational parameters like pH, hydrogen peroxide dosage and iron concentration were optimized in case of DF and PF processes, whereas in case of EF process, applied voltage and hydrogen peroxide dosage were optimized to make water biocompatible for subsequent biological degradation. The use of Fenton applications as a pre-treatment resulted in a significant enhancement in the BOD5/COD ratio validating the production of easily degradable metabolites or secondary products. Overall results indicated that among the utilized Fenton technologies, pre-treatment of pharmaceutical wastewater with PF lead to better COD and TOC removal efficiency with subsequent biological degradation when compared to DF and EF pre-treatment. Overall COD removal efficiency of the combined PF and biological treatment was around 84% for LSW and 82% for HSW. Conclusively, it can be established that combined Fenton applications as pretreatment technology and biological treatment is more effective approach in comparison to single stage oxidation either by Fenton or biological treatment. Cytotoxicity assessment revealed that complete detoxification of wastewaters were achieved indicating that hybrid treatment technology of Fenton’s and biological treatment did not exhibited any toxicity against the selected microbes.

Resistance in the Environment

Abstract: 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.

Anthropogenic aerosols and the weakening of the South Asian summer monsoon

Abstract: Changes in monsoon rainfall are caused by human-produced aerosols slowing the tropical atmospheric circulation. Observations show that South Asia underwent a widespread summertime drying during the second half of the 20th century, but it is unclear whether this trend was due to natural variations or human activities. We used a series of climate model experiments to investigate the South Asian monsoon response to natural and anthropogenic forcings. We find that the observed precipitation decrease can be attributed mainly to human-influenced aerosol emissions. The drying is a robust outcome of a slowdown of the tropical meridional overturning circulation, which compensates for the aerosol-induced energy imbalance between the Northern and Southern Hemispheres. These results provide compelling evidence of the prominent role of aerosols in shaping regional climate change over South Asia.

Production and applications of activated carbons as adsorbents from olive stones

Abstract: Olive stones have been widely used as a renewable energy biowaste source. As they are rich in elemental carbon (40–45 wt%), much research focussed on effectively converting olive stones, as precursors, into activated carbon adsorbents. However, only a few studies have concentrated on summarising the various techniques used to produce activated carbon from olive stone. This article reviews the research undertaken on the production and application of activated carbon as an adsorbent from olive stones for wastewater treatment. Various physical, chemical and physico-chemical treatments to remove heavy metals, organics and dyes are discussed, and the resultant adsorption capacities are reported. In several cases, very high adsorption capacities are recorded. Finally, the future prospects of these materials as adsorbents are discussed, and after further development work, olive stone-derived activated carbons have great potential especially in the area of organic polluted wastewaters.