Mathematical Modeling for the Design of Greenbelts for Air Pollution Control: An Engineering Perspective

Addressing transgender health in a Lancet Series and in The Lancet Psychiatry1 constitutes a milestone for health professionals and social scientists. I draw conclusions from some of these papers on how we consider health, disease, and gender, and on the purpose of the nomenclatures we have developed and use

Small hydro and the environmental implications of its extensive utilization

There is a great resurgence of interest all over the world in the development of 'small' hydropower systems (SHS). The surge is essentially propelled by the belief that SHS, which include mini, micro, and picahydel systems, are a source of clean energy with little or no adverse impacts on the environment. This paper presents an overview of SHS and then examines in detail whether the prevalent belief in the great environment-friendliness of SHS is really justified. It is brought out that widespread use of SHS is likely to cause, per kilowatt of power generated, no less significantly adverse environmental impacts than large hydropower systems and some other conventional sources of energy. While supporting the ongoing global efforts to maximize the use of SHS, the authors advocate much greater circumspection than is being exercised at present vis-a-vis SHS. The authors believe that if the likely pitfalls are foreseen before SHS are put to widespread use, and remedial measures taken accordingly, it may save the world from considerable disillusionment and environmental damage.

'Renewable' hydrogen: Prospects and challenges

The increasingly manifest impacts of global warming have made it a global priority to phase out the use of petrol and diesel as transportation fuels in favour of hydrogen. But the production of hydrogen by most existing technologies entails substantial use of fossil fuels and CO2 emissions; indeed as much as 2.5-5 tonnes of carbon is released as CO2 per tonne of hydrogen currently produced by conventional means. Hence the production of hydrogen can be 'carbon-free' only if it is generated by employing genuinely carbon-free renewable energy sources. The present review deals with the options, prospects, and challenges associated with this very high-priority area of global concern.Renewable hydrogen Solar hydrogen Wind-to-hydrogen OTEC hydrogen

Production of clean energy by anaerobic digestion of phytomass--New prospects for a global warming amelioration technology

Anaerobic digestion of animal dung generated combustible gas - this fact has been known since over 130 years and has been gainfully utilized in generating clean energy in the form of methane-rich 'biogas'. During 1970s it was found that aquatic weeds and other phytomass, if anaerobically digested, also produced similarly combustible 'bio' gas. It raised great hopes that anaerobic digestion of phytomass will also enable generation of biogas that too on a much larger scale than is possible with animal manure. This, it was hoped, would also provide a means for utilizing weeds, crop wastes, and biodegradable municipal solid waste which otherwise cause environmental pollution. It appeared to be a 'no lose' possibility; it was hoped that soon the problems of weeds (and other biosolid wastes) as well as energy shortage, would vanish. At that time there was little realization of the global warming (GW) potential of methane nor of the fact that natural degradation of phytomass in the environment is causing massive quantities of GW gas emission. Hence, at that time, the potential benefits from anaerobic digestion of phytomass were perceived only in terms of pollution control and energy generation. But four decades have since elapsed and there is still no economically viable technology with which weeds and phytowastes can be gainfully converted to energy. This paper takes a look at what has happened and why. It also points towards the possibility of success finally emerging on the horizon. It would, hopefully, give a fresh impetus to the entire field of biomethanation R&D because all 'methane capture' technologies also indirectly contribute to very significant reduction in global warming.Anaerobic digestion Biogas Global warming Manure Methane Phytomass

Biomass energy and the environmental impacts associated with its production and utilization

Biomass is the first-ever fuel used by humankind and is also the fuel which was the mainstay of the global fuel economy till the middle of the 18th century. Then fossil fuels took over because fossil fuels were not only more abundant and denser in their energy content, but also generated less pollution when burnt, in comparison to biomass. In recent years there is a resurgence of interest in biomass energy because biomass is perceived as a carbon-neutral source of energy unlike net carbon-emitting fossil fuels of which copious use has led to global warming and ocean acidification. The paper takes stock of the various sources of biomass and the possible ways in which it can be utilized for generating energy. It then examines the environmental impacts, including impact vis a vis greenhouse gas emissions, of different biomass energy generation-utilization options.

Correction: Tabassum Abbasi et al., Modelling Methane and Nitrous Oxide Emissions from Rice Paddy Wetlands in India Using Artificial Neural Networks (ANNs). Water 2019, 11, 2169

The authors wish to make the following corrections to this paper [...

Feasibility of a Novel (SHEFROL) Technology in Pre-Treating Eatery Wastewater at Pilot Scale

The wastewater ensuing from public eateries is higher in its chemical and biological oxygen demand (COD and BOD) as also its oil, grease, and protein content than sewage. For this reason such wastewater is much harder to treat; its content of fats, proteinaceous material, and xenobiotics mounting major challenges. But in most of the developing world about 80% of such wastewater is discharged untreated and the remaining is mixed with sewage going to the treatment plants. This happens due to the prohibitively high cost of treatment that is entailed if these wastewaters are to be treated by conventional activated sludge processes (ASPs) or a combination of anaerobic digestion and ASPs. The practice of allowing eatery wastewater to join sewage en route sewage treatment plants increases the load on the latter, especially due to the high fat and protein content of the former. The present work describes attempts to use the recently developed and patented SHEFROL® technology in affecting treatment of wastewater coming from a typical eatery. After establishing feasibility at bench scale, the process was tested in a case study at pilot plant scale for treating 12,000 litres/day (LPD) of wastewater being generated by the eateries situated in the campus of Pondicherry University, India. The capacity of the pilot plant was then expanded to 30,000 LPD. Despite operating the units at a very low hydraulic retention time (HRT) of 2 ± 0.5 h, due to the limitations of land availability, which translates to a rate about three times faster than a typical ASP, over 50% removal of COD and BOD, and similarly substantial removal of other pollutants was consistently achieved. Given that the SHEFROL units can be set up at a negligible cost, the findings indicate that SHEFROL technology can be used to significantly yet inexpensively pre-treat eatery wastewaters before either sending them for further treatment to conventional sewage treatment plants, higher-end SHEFROL units, or discharging them directly if neither of the other two options is available

Modelling Methane and Nitrous Oxide Emissions from Rice Paddy Wetlands in India Using Artificial Neural Networks (ANNs)

Paddy fields, which are shallow man-made wetlands, are estimated to be responsible for ~11% of the total methane emissions attributed to anthropogenic sources. The role of water use in driving these emissions, and the apportioning of the emissions to individual countries engaged in paddy cultivation, are aspects that have been mired in controversy and disagreement. This is largely due to the fact that methane (CH4) emissions not only change with the cultivar type but also regions, climate, soil type, soil conditions, manner of irrigation, type and quantity of fertilizer added—to name a few. The factors which can influence these aspects also encompass a wide range, and have origins in causes which can be physical, chemical, biological, and combinations of these. Exceedingly complex feedback mechanisms, exerting different magnitudes and types of influences on CH4 emissions under different conditions, are operative. Similar is the case of nitrous oxide (N2O); indeed, the present level of understanding of the factors which influence the quantum of its emission is still more patchy. This makes it difficult to even understand precisely the role of the myriad factors, less so model them. The challenge is made even more daunting by the fact that accurate and precise data on most of these aspects is lacking. This makes it nearly impossible to develop analytical models linking causes with effects vis a vis CH4 and N2O emissions from paddy fields. For situations like this the bioinspired artificial intelligence technique of artificial neural network (ANN), which can model a phenomenon on the basis of past data and without the explicit understanding of the mechanism phenomena, may prove useful. However, no such model for CH4 or N2O has been developed so far. Hence the present work was undertaken. It describes ANN-based models developed by us to predict CH4 and N2O emissions using soil characteristics, fertilizer inputs, and rice cultivar yield as inputs. Upon testing the predictive ability of the models with sets of data not used in model development, it was seen that there was excellent agreement between model forecasts and experimental findings, leading to correlations coefficients of 0.991 and 0.96, and root mean square error (RMSE) of 11.17 and 261.3, respectively, for CH4 and N2O emissions. Thus, the models can be used to estimate CH4 and N2O emissions from all those continuously flooded paddy wetlands for which data on total organic carbon, soil electrical conductivity, applied nitrogen, phosphorous and potassium, NPK, and grain yield is available

A Comparative Study of the Fertilizer-Cum-Pesticide Effect of Vermicomposts Derived from Cowdung and the Toxic Weed Lantana

The effect of vermicomposts, derived either from cowdung or the pernicious invasive plant lantana (Lantana camara), has been assessed on the seed germination, plant growth, fruit yield, quality of the produce, and disease resistance of a common vegetable, ladies finger (Abelmoschus esculentus).Seeds of A. esculentus were germinated and grown in soil fertilized with 0, 2.5, 3.75 and 5 t ha−1 of lantana or cowdung vermicompost for 4 months. It was seen that the lantana vermicompost performed at par or better than the cowdung vermicompost in terms of most of the growth and yield parameters observed. Both the vermicomposts encouraged the germination, growth as well as the yield of ladies fingers. The fruits harvested from the vermicompost-treated plots had greater concentrations of minerals, proteins and carbohydrates than the control plants. Vermicomposts also reduced the incidence of pest attacks on the plants. The results confirm that vermicomposting destroys the harmful ingredients of lantana and turns it into as good a biofertilizer, perhaps even better than the vermicompost of cow-dung. The very large quantities of lantana biomass that is generated in the tropical and sub-tropical regions of the world every year, which presently go to waste, now appear capable of becoming a source of organic fertilizer