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In the context of the absence of any prior art on the vermicomposting of any xerophyte—presumably because xerophytes, in general, are structurally tough and have attributes which help them resist biodegradation—the present work has been undertaken. It has led to a procedure which makes even the highly toxic leaves of prosopis amenable to vermicomposting. Two years long and continuous operation of vermireactors with six different species of earthworms, has shown that the earthworms gradually adapted to prosopis as their exclusive feed, showing a consistently increasing rate of vermicast production while remaining healthy and displaying good fecundity throughout. The work provides an avenue of utilizing prosopis leaves which are generated in very large quantities across the tropical and sub-tropical world. At present no process exists which can make use of prosopis leaves even as the wood of its trees is utilizable. Besides valorizing an otherwise wasted phytomass the present work will also prevent falling of prosopis leaves on soil and their very slow biodegradation during which they toxify the soil with allelochemicals and emit global warming gases.

The potential application of a novel continuous electrocoagulation (EC) reactor for simultaneous removal of color, chemical oxygen demand (COD), turbidity, and alkalinity from a real licorice processing wastewater was investigated. The individual and interactive effects of four key independent variables (electrolysis time, current density, NaCl concentration, and mixing intensity) was evaluated. The results suggested that color and COD removal enhances with increasing electrolysis time, current density, and mixing intensity and remains practically constant by adding higher concentrations of NaCl. The application of continuous EC process under optimal conditions, such as: electrolysis time (81.8 min), current density (350 A/m2), NaCl concentration (300 mg/L), mixing intensity (45 rpm) allows to achieve these promised removal efficiencies: 90.1 % color, 89.4 % COD, 82 % turbidity, and 73.3 % alkalinity.

Majority of the accidents occurring in chemical process industry begin with the accidental spill of one or the other liquid fuel. This makes it important to forecast the areas likely to be covered by the spill of a given fuel on a given surface of a given inclination, and to devise accident prevention strategies on its basis. This work reviews all the reported models for forecasting the area attained by a liquid spill at equilibrium. It then evaluates the efficacy of these models by testing them with available data. It was possible to run four of the six reported models as data was not adequate to operate the remaining two. It is seen that three of the four models thus tested under-predicted the spill area for some liquid―surface combinations and over-predicted it for some others the percentage error covering large ranges. Only one model consistently under-predicted the area and did so in a much narrower error range. After a ‘weight’ or a ‘correction factor’ was attached to that model it was able to forecast spill area with adequate accuracy.

In separate treatments rice (Oryza sativa) of the Chinna Ponni variety was grown either with the application of synthetic fertilizer (SF) containing 120 kg/ha, 60 kg/ha, and 60 kg/ha of nitrogen, phosphorous, and potassium, respectively, or vermicompost (4 t/ha) with equivalent nitrogen content. The objective was to see whether vermicompost performs as well, or better, than the SF in terms of grain length, unit mass, and overall yield of rice. The relative contribution of the two fertilizer applications on the emission of the global warming gas methane was also studied. Direct sowing method was applied for the rice cultivation which spanned 140 days during which intermittent flooding of the plots was done. The average grain yield (2300 kg/ha), grain weight (21 mg), and grain length (6.3 mm) of the vermicompost-fertilized rice were all marginally higher than the corresponding values: 2060 kg/ha, 18 mg, and 6.1 mm, respectively, of the SF-fertilized rice. The overall hourly methane flux in vermicompost-fertilized plots was 111.3 ± 58.3 µg/m2 h in comparison with 71.0 ± 81.0 µg/m2 h emitted by the SF-fertilized plots, but the difference was not statistically significant.

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

Twentyeight accidents involving major fires and/or explosions, which have occurred across the world in tank farms storing flammable liquids, have been studied. The focus has been on determining, a) what were the distances between the tank which failed and the tank(s) which were damaged or could have been damaged due to fire/explosion in the former; b) what were the distances prescribed as safe by prevailing codes/standards/models between the concerned tanks, and c) whether the tanks were relocated in a safer way by the concerned industry after the accident. The study also identifies some of the codes, standards, and models which appear to provide more realistic safe distances for the given tank types/sizes.

The ornamental plant Alternanthera ficoidea (also named A. tenella), which is common and widespread throughout the tropics and is being increasingly regarded as an invasive, problematic weed, has been explored as a bioagent in greywater treatment. In the recently developed SHEFROL® bioreactor, it was seen to treat greywater of varying strengths (250–1,300 mg/L chemical oxygen demand, COD) quickly and substantially to the extent of 75–77%. Biological oxygen demand (BOD), nitrogen, phosphorus, suspended solids, and heavy metals copper, nickel, manganese, and zinc were also removed to the extents of 83.5, 94.9, 33.1, 27.0, 44.8, 27.5, 38.2, and 43.2%, respectively. As all this was achieved in a single pot, single step, and in a simple reactor operation, at hydraulic retention times of a mere 6 h, it shows the process to be several times more efficient as well as potentially less expensive than the conventional treatment systems which utilize macrophytes in tanks or constructed wetlands.

The use of probits is essential for the study of domino effect in chemical process industries, to enable the assessment of the probability of escalation of accidents. This paper reports a more comprehensive and reliable method for formulating the probits than has been accomplished by the earlier reported methods. It is based on a larger data set, a finer level of classification of the equipment and a different method of linking the qualitative description of the damage to the quantitative probability. The probits thus obtained have significantly higher coefficients of determination (R2) than those obtained by the previous authors, indicating a much better interpretation of the past data for calculating the probits. In most cases, the R2 was greater than 0.9.

Characteristics of the highly pernicious weed ipomoea ( Ipomoea carnea ) were studied before and after its vermicomposting by the earthworm ( Eisenia fetida ). The studies, supported by UV–visible and Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) and differential scanning calorimetry (DSC), gas chromatography–mass spectrometry (GC–MS), and scanning electron microscopy (SEM) reveal a drastic change in the characteristics. There was a sharp reduction in the carbon-to-nitrogen ratio from 26.1 to 9.9, and in humification index from 7.7 to 1.9. By all accounts there was substantial mineralization of organic matter. Complex aromatics such as lignin and polyphenols were degraded into simpler carbohydrates and lipids. GC–MS analysis showed significant fragmentation, bio-oxidation and molecular rearrangements of chemical compounds in vermicompost in comparison to those in ipomoea. SEM micrographs of ipomoea vermicompost reflected strongly disaggregated material compared to ipomoea. The phenols and alkaloids which are specifically responsible for the toxicity and allelopathy of ipomoea, were significantly degraded in the course of the weed's vermicomposting, turning it into a plant-friendly organic fertilizer. These findings make it appear possible that millions of tons of ipomoea biomass, which is generated annually but goes to waste, can be transformed into organic fertilizer.

Vermicompost, which had been derived solely by the action of the epigeic earthworm Eisenia fetida on parthenium (Parthenium hysterophorus), was tested for its impact on the germination and early growth of green gram (Vigna radiata), ladies finger (Abelmoschus esculentus) and cucumber (Cucumis sativus). Seedlings were germinated and grown in soil amended with 0 (control), 0.75, 1.5, 2, 4, 8, 20 and 40% (by weight) parthenium vermicompost. Even though parthenium is known to possess strong negative allelopathy, as also plant/animal toxicity in other forms, its vermicompost (VC) manifested none of these attributes. Rather the VC enhanced germination success, introduced plant-friendly physical features in the container media, increased biomass carbon, and was seen to promote early growth as reflected in several morphological and biochemical characteristics in plants which had received parthenium VC in comparison to those which had not. All these effects were statistically significant. Fourier Transform Infrared (FTIR) Spectrometry revealed that the phenols and the sesquiterpene lactones that are responsible for the negative allelopathic impact of parthenium were largely destroyed in the course of vermicomposting. FTIR spectra also indicated that lignin content of parthenium was reduced during its vermicomposting. The findings open up the possibility that several other invasives known for their negative allelopathy and toxicity may also produce vermicompost which may be plant-friendly and soil-friendly. It also makes it appear possible that the huge quantities of phytomass that is generated annually by parthenium can be gainfully utilized in producing organic fertilizer via vermicomposting, thereby providing a means of exercising some control over parthenium's rampant growth and invasion.

In evidently the first study of its kind, vermicompost derived solely from salvinia (Salvinia molesta Mitchell), arguably the world’s most invasive and dominant aquatic weed, has been assessed for its nature and composition. Salvinia is known to contain exceptionally high concentrations of polyphenols, and has unusually ligneous leaves—the two attributes that make it strongly allelopathic and hardy, enabling it to elbow out other vegetation. The present study, supported by UV–vis and FTIR spectrometry, thermogravimetric and differential thermal analysis, and GS-MS analysis, reveals that upon vermicomposting salvinia loses its allelopathy. It happens because chemicals responsible for the alleopathy of salvinia are destroyed, transforming the weed into a potent organic fertilizer. Much of the salvinia’s lignin is also biodegraded. Scanning electron microscopy shows marked disaggregation of the material in the vermicompost as compared to well-formed matrix of salvinia leaves. The findings open up the possibility of utilizing billions of tonnes of salvinia biomass – which not only goes to waste at present but is also a cause of serious harm to the environment – in making organic fertilizer.

We report for the first time the capability of four-leaf clover (Marsilea quadrifolia), a wetland plant which grows rooted in soil, in efficiently treating sewage. The use of M. quadrifolia was made possible because of the special attributes of the SHEFROL® (SHEet Flow ROot Level) bioreactor in which it was employed. This bioreactor enables the use of free-floating aquatic plants as well as terrestrial and rooted-in-soil wetland plants by hydroponics. The plants are staked in narrow channels to enable them to support each other while sewage is made to flow rapidly as a sheet of wastewater at a level that covers only the plant roots (hence the name). It was seen that M. quadrifolia was able to treat sewage of strength varying in the chemical oxygen demand (COD) range of 600–1800 mg/L to the extent of > 80% at a hydraulic retention time (HRT) of just 4.5 h. There was a near total removal of biological oxygen demand and suspended solids while total Kjeldahl nitrogen, soluble phosphorous, and heavy metal zinc were also substantially removed. The macrophyte was equally effective when used indoors under artificial lighting, as well as when used outdoors.

A rapid, reproducible single step method is proposed for synthesizing platinum nanoparticles using an invasive weed lantana (Lantana camara, L). The method involves mixing of platinum (VI) solution, lantana leaf extract and ascorbic acid in appropriate concentrations and keeping the mixture at 95°C for 8 min. The collective action of ascorbic acid and leaf extract reduced the chloroplatinic acid to platinum nanoparticles and leaf extract then served the additional purpose of stabilizing the nanoparticles. The resulting nanoparticles have an average size of 35 nm and crystallized in face centred cubic symmetry. The course of the synthesis was trekked by UV-visible spectrophotometry and the characterization of the nanoparticles was done with scanning electron microscopy and confocal laser Raman spectroscopy. Particle size distribution was estimated by dynamic light scattering and the crystal structure was determined by XRD. The purity of the product was checked by EDAX.

In evidently the first study of its kind, vermicompost derived solely from a weed known to possess plant and animal toxicity was used to assess its impact on the germination and early growth of several plant species. No pre-composting or supplementation of animal manure was done to generate the vermicompost in order to ensure that the impact is clearly attributable to the weed. Whereas the weed used in this study, Lantana (Lantana camara), is known to possess strong negative allelopathy, besides plant/animal toxicity in other forms, its vermicompost was seen to be a good organic fertilizer as it increased germination success and encouraged growth of all the three botanical species explored by the authors - green gram (Vigna radiata), ladies finger (Abelmoschus esculentus) and cucumber (Cucumis sativus). In terms of several physical, chemical and biochemical attributes that were studied, the vermicompost appeared plant-friendly, giving best results in general when employed at concentrations of 1.5% in soil (w/w). Fourier transform infrared spectrometry revealed that the phenols and the sesquiterpene lactones that are responsible for the allelopathic impact of Lantana were largely destroyed in the course of vermicomposting. There is also an indication that lignin content of Lantana was reduced during its vermicomposting. The findings open up the possibility that the billions of tons of phytomass that is generated annually by Lantana and other invasives can be gainfully utilized in generating organic fertilizer via vermicomposting.

We report for the first time the utilization of a highly invasive weed Antigonon leptopus in synthesizing gold nanoparticles. For this purpose, aqueous extracts of the weed's leaves/stem/roots served the dual purpose of reducing gold ions to uncharged metal nanoparticles and then capping the nanoparticles thus formed to stabilize them. The synthesis occurs very swiftly leading to spherical, hexagonal, or triangular nanoparticles. The influence of the key variables that control the shape/size of the gold nanoparticles (AuNPs)—concentrations of the extract relative to Au (III), temperature, interaction time, stirring, and pH-was studied employing UV–visible spectrophotometry, scanning electron microscopy, transmission electron microscopy, energy dispersive analysis of X-rays, dynamic light scattering (DLS), X-ray diffraction, and Fourier transform infrared spectroscopy. Besides being simple and rapid, the present process is distinguished by its ability to gainfully utilize an otherwise harmful plant in a manner which consumes little energy and generates no waste emissions. The AuNPs were found to catalyze the degradation of organic pollutants Congo red and Remazol Brilliant Blue R. © 2015 American Institute of Chemical Engineers Environ Prog, 2015

When two or more pool fires happen to burn so close to each other that they interact, they are termed ‘multiple pool fires’ (MPF). Past accident analysis reveals that MPFs occur quite frequently in chemical process industries. Controlled experiments done so far to study MPFs have indicated that MPFs lead to increase in the fuel burning rate, flame height and heat release rate (HRR) but the nature and the extent of the impacts of different factors on these manifestations is as yet poorly understood. In this context computational fluid dynamics (CFD) appears to be a tool which can enable more detailed and realistic simulation of MPFs than other possible approaches, especially due to its ability to closely approximate the underlying physical phenomena. In tank farms there are situations where different storage tanks are placed at different elevations yet close to each other. If such tanks happen to catch fire, the resulting fires may influence each other in a manner that may be a function of the difference in the tanks’ elevation. However no CFD study has been carried out which addresses this type of situation. Hence an attempt has been made to employ CFD to study MPFs involving two pools with fuel surfaces are at different elevations. Results reveal that good correlation is possible between the experimental findings and the CFD simulations.

Hydroponics, a Greek word which literally means ‘water working’, represents horticulture without the use of soil. It has been attempted since thousands of years and descriptions are available of gardens developed wherein trees and shrubs were grown without any soil support but by supplying nutrient-rich water directly to the plant roots. In recent times, hydroponics has been explored as a means of water treatment in which biochemical, physical, and microbiological processes occurring in plant roots are harnessed to improve the quality of polluted water. Here, we present state of the art of wastewater treatment by hydroponics and introduce a novel bioreactor named SHEFROL® developed by us, of which a patent claim has been registered.

The beneficial effects of vermicast on soil fertility in general, and agriculture in particular, are widely recognized, but there are no reports on the effect of storage on vermicast quality. The present study is an attempt to cover this knowledge gap as it may assist in the formulation of guidelines for packaging and storing of vermicast in a manner that preserves the cast’s fertilizer value. Vermicast generated from paper waste was packed in airtight and partially sealed bags with and without pre-drying for 24 h. Changes in several physical, chemical, and biological properties of the castings were monitored for 3 months with weekly assessments. The results reveal that the beneficial properties of vermicast were the highest when it was fresh. There was deterioration on storage, which can be minimized if the castings are contained in airtight bags after pre-drying the casts.

Even as the world has been unsuccessfully trying to dispose off the rising quantities of its municipal solid waste (MSW) and hazardous waste (HW) in a clean manner, it has been confronted with an even more complex problem—of e-waste. Only a few countries in the developed world are able to scientifically recycle or dispose the e-waste they generate. In other developed countries only a fraction of the e-waste is properly recycled, the rest is either incinerated or sent to landfills—which are solutions that cause serious secondary problems. Worse still, a sizeable portion of the e-waste generated in the developed world is exported to developing countries where it is recycled or dumped without any concern for the gross pollution that is being caused. It can be said that if the situation vis-a-vis e-waste is posing a challenge in most developed counties, it is alarmingly bad in the developing world. In an attempt to contain the e-waste problem most of the developed world and several countries in the developing...

Of all the renewable energy sources (RESs)―except direct solar heat and light―wind energy is believed to have the least adverse environmental impacts. It is also one of the RES which has become economically affordable much before several other RESs have. As a result, next to biomass (and excluding large hydro), wind energy is the RES being most extensively tapped by the world at present. Despite carrying the drawback of intermittency, wind energy has found favor due to its perceived twin virtues of relatively lesser production cost and environment-friendliness. But with increasing use of turbines for harnessing wind energy, the adverse environmental impacts of this RES are increasingly coming to light. The present paper summarizes the current understanding of these impacts and assesses the challenges they are posing. One among the major hurdles has been the NYMBI (not in my backyard) syndrome due to which there is increasing emphasis on installing windfarms several kilometers offshore. But such moves have serious implications for marine life which is already under great stress due to impacts of overfishing, marine pollution, global warming, ozone hole and ocean acidification. Evidence is also emerging that the adverse impacts of wind power plants on wildlife, especially birds and bats, are likely to be much greater than is reflected in the hitherto reported figures of individuals killed per turbine. Likewise recent findings on the impact of noise and flicker generated by the wind turbines indicate that these can have traumatic impacts on individuals who have certain predispositions. But the greatest of emerging concerns is the likely impact of large wind farms on the weather, and possibly the climate. The prospects of wind energy are discussed in the backdrop of these and other rising environmental concerns.

Anaerobic digestion often generates ‘biogas’ – an approximately 3:1 mixture of methane and carbon dioxide – which has been known to be a ‘clean’ fuel since the late 19th century. But a great resurgence of interest in biogas capture – hence methane capture – has occurred in recent years due to the rapidly growing spectre of global warming. Anthropogenic causes which directly or indirectly release methane into the atmosphere, are responsible for as much as a third of the overall additional global warming that is occurring at present. Hence the dual advantage of methane capture – generating energy while controlling global warming – have come to the fore. This paper presents an overview of the natural and the anthropogenic sources that contribute methane to the atmosphere. In this context it underscores the urgency with which the world must develop and enforce methods and practices to enhance methane capture.

Contrary to the popular perception that rainwater harvested from rooftops is nearly as clean as pure water, a number of contaminants can be present in such a water—this is borne out by numerous studies reviewed by the authors. Once this fact is acknowledged, it is possible to control the water quality and to bring it within acceptable levels with simple and inexpensive devices. The authors address these issues. Besides reviewing the status of the quality of harvested rainwater, they trace the pathways by which pollutants can enter in a rainwater harvest. In this backdrop the authors discuss the strategies to manage the water quality at preharvest as well as postharvest stages.

It has always been a widely prevalent belief that renewable energy sources are clean and green in contrast to nonrenewable fossil fuels. The oil price shocks of 1973 and 1979, alongside increasing global awareness towards environmental pollution had stimulated great interest in the development of renewable energy sources during the early 1980s. But as the oil prices came down and few breakthroughs were achieved in that period for making the cost of renewable energy comparable or lesser to fossil fuel energy, the enthusiasm of the early 1980s began to wane. In more recent years the spectres of global warming and ocean acidification, which have been primarily attributed to fossil fuel burning, has caused a resurgence of interest in renewable energy sources. As illustrated in this article, scientists from all over the world are strongly advocating large-scale substitution of conventional energy sources with renewable alternatives on the premise that such a move would substantially reduce environmental degrad...

Ocean acidification is the newest global environmental threat confronting the earth. It is the consequence of the same anthropogenic excess that is responsible for global warming—release of much more CO2 at much faster rates, minute after minute, than the earth's capability to assimilate. Considering that oceans cover almost 70% of the earth's surface, any upset in the balance of forces in the oceans due to anthropogenic CO2 emissions has, potentially, much more massive consequences than the impacts scientists are witnessing on the rest 30% of the earth. Ocean acidification is the name given to the lowering of ocean pH that is beginning to occur because the oceans are being forced to absorb CO2 at a much faster rate during the last few decades than it has been over the previous thousands of years. The term does not imply that the oceans have actually become acidic, or will become acidic in the near future; it signifies a shift of ocean pH toward less alkaline levels. This shift has already threatened cora...

With the world reaching near-total consensus on the seriousness of the global warming impacts, and on the urgency to halt further warming, R & D efforts have intensified many-fold to find ways and means of global warming control. One of the avenues being explored is ‘decarbonization’ of fossil fuel use by either decarbonizing the fuels before they are burnt or by capturing the CO2 they emit on combustion. In this paper the various available options are reviewed in the context of their economic and environmental viability. It emerges that even as the goal is very enchanting, the possibility of it's realization appears remote. It also follows that the only sure method of reducing greenhouse gas emissions presently available to humankind is by reducing consumption of energy and other resources.

Water quality indices (WQIs), which translate numerical values of several water quality characteristics of a sample into a single value, play a very important role in the monitoring, comparison and control of water quality. The WQIs of modern and post-modern times have been almost exclusively based on physical and chemical characteristics, and have seldom included ‘biological’ characteristics other than biochemical oxygen demand (BOD) and faecal coliforms. During the last three decades of the 20th century, indices based on bioassessment have been increasingly used in some developed countries, besides South Africa and Serbia, to complement the conventional WQIs, but the rest of the world continues to base its WQIs predominantly on physical and chemical characteristics. The serious drawbacks of this approach have been elucidated in this paper and, against that background, the state-of-the-art of biotic indices has been summarized. The paper makes a strong case for greater reliance on bioassessment-based WQIs, especially by developing countries, to strengthen the diagnostic value of the conventional WQIs.

Aquatic weeds such as water hyacinth, salvinia, pistia, and lemna have proved to be powerful bioagents which significantly purify wastewater lying under them. Even the performance of conventional oxidation ponds can be greatly enhanced by the simple expedient of introducing one of these aquatic weeds. Weeds absorb certain pollutants. But the contribution of absorption to the overall treatment is only one among several contributory factors. This paper examines the factors responsible for the water‐purifying ability of the weeds.

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.

Vermicomposting of the pre-composted leaf litter of acacia (Acacia auriculiformis) was studied in reactors of identical volume but with surface area: height ratios varying from 4 to 250. In separate sets of experiments with these reactors, epigeic earthworm species Eudrilus eugeniae and anecic earthworm species Lampito mauritii were employed at densities of 75 and 150 adult animals per litre of reactor volume. The results reveal that greater the surface area: volume ratio of the reactor, higher is the vermicast output in terms of vermicast output per animal; the more densely populated reactors were comparatively under-productive. Even as the vermicast production remained consistently high in all the reactors, there was significant earthworm mortality throughout the course of the experiments and the worms who survived, steadily lost weight with time. A detailed investigation of the possible causes revealed that, whereas the C:N ratio of acacia compost was comparable with that of other substrates; the polyphenols and lignin content were much higher. Studies by other authors on leaf litter consumption by earthworms in natural or man-made forests have indicated that leaf litter rich in polyphenols and lignin are not preferred by most species of earthworm. This may perhaps be the reason for the high rate of mortality and weight loss in earthworms forced to feed upon acacia in the experiments conducted by the authors.

One of the most versatile and remunerative techniques for handling biodegradable solid wastes is composting. A large variety of such wastes of plant, animal, and synthetic origins can be gainfully composted, at scales varying from a household bin to a large industry. Compost also has an inexhaustible market as a soil conditioner and fertilizer. Apart from being a source of nitrogen, phosphorus, potassium, and other nutrients for plants, compost is also believed to suppress soil-borne diseases in plants. These virtues make composting an ideal option for processing the enormous quantities of biodegradable solid wastes that are generated in the world. In this article, a review of the state of the art of compost science is presented, encompassing the history, the mechanism, the production, the characteristics, and the effects of composting. It is hoped that this effort would stimulate further interest in composting and in the appreciation of its benefits.

Studies are presented on new types of anaerobic digesters in which chopped or dry crushed Ipomoea carnea was fed without any other pretreatment, in an attempt to develop commercially viable means of utilizing the otherwise very harmful plant. Two types of solid-feed anaerobic digesters (SFADs) were studied. The first type had a single vessel in which the bottom 35% portion was separated from the top portion by a perforated PVC disk. The weed was charged from the top and inoculated with anaerobically digested cowdung-water slurry. The fermentation of the weed in the reactor led to the formation of volatile fatty acids (VFAs) plus some biogas. The leachate, rich in the VFAs, was passed through the perforated PVC sheet and collected in the lower portion of the vessel. The other type of reactors had two vessels, the first one was fully charged with the weed and the second received the VFA leachate. With both types were attached upflow anaerobic filters (UAFs) which converted the leachate into combustible biogas consisting of approximately 70% methane. All SFADs developed very consistent performance in terms of biogas yield within 17 weeks of start. The two-compartment reactors yielded significantly more biogas than the single-compartment reactors of corresponding total volume, and the reactors with which anaerobic filters (AF) were attached yielded more biogas than the ones without AF. The best performing units generated 2.41m(3) of biogas per m(3) of digester volume, as compared to 0.1-0.2m(3) of biogas, m(-3)d(-1), obtainable with conventional digesters. This indicates the viability of this technology. The spent weed can be vermicomposted directly to obtain good soil-conditioner cum fertilizer; earthworm Eudrilus eugeniae produced 540mg vermicast per animal every day, achieving near total conversion of feed to vermicast in 20 days. The proposed systems, thus, makes it possible to accomplish total utilization of ipomoea.

Among the most devastating of accidents likely in chemical process industry is the boiling liquid expanding vapour explosion (BLEVE). It is accompanied by highly destructive blast waves and missiles. In most situations there is also a fireball or a toxic gas cloud. The damaging effect of BLEVEs is reflected in the fact that the 80-odd major BLEVEs that have occurred between 1940 and 2005 have claimed over a 1000 lives and have injured over 10,000 persons besides harming property worth billions of dollars. Release of toxic chemicals like chlorine and phosgene from BLEVEs have damaged large chunks of areas surrounding the BLEVE site. This paper presents an overview of the mechanism, the causes, the consequences, and the preventive strategies associated with BLEVEs.

Dust explosions pose the most serious and widespread of explosion hazards in the process industry alongside vapour cloud explosions (VCE) and boiling liquid expanding vapour explosions (BLEVE). Dust explosions almost always lead to serious financial losses in terms of damage to facilities and down time. They also often cause serious injuries to personnel, and fatalities. We present the gist of the dust explosion state-of-the-art. Illustrative case studies and past accident analyses reflect the high frequency, geographic spread, and damage potential of dust explosions across the world. The sources and triggers of dust explosions, and the measures with which different factors associated with dust explosions can be quantified are reviewed alongside dust explosion mechanism. The rest of the review is focused on the ways available to prevent dust explosion, and on cushioning the impact of a dust explosion by venting when the accident does take place.

The strategies to prevent accidents from occurring in a process industry, or to minimize the harm if an accident does take place, always revolve around forecasting the likely accidents and their impacts. Based on the likely frequency and severity of the accidents, resources are committed towards preventing the accidents. Nearly all techniques of ranking hazardous units, be it the hazard and operability studies, fault tree analysis, hazard indice, etc.--qualitative as well as quantitative--depend essentially on the assessment of the likely frequency and the likely harm accidents in different units may cause. This fact makes it exceedingly important that the forecasting the accidents and their likely impact is done as accurately as possible. In the present study we introduce a new approach to accident forecasting based on the discrete modeling paradigm of cellular automata. In this treatment an accident is modeled as a self-evolving phenomena, the impact of which is strongly influenced by the size, nature, and position of the environmental components which lie in the vicinity of the accident site. The outward propagation of the mass, energy and momentum from the accident epicenter is modeled as a fast diffusion process occurring in discrete space-time coordinates. The quantum of energy and material that would flow into each discrete space element (cell) due to the accidental release is evaluated and the degree of vulnerability posed to the receptors if present in the cell is measured at the end of each time element. This approach is able to effectively take into account the modifications in the flux of energy and material which occur as a result of the heterogeneous environment prevailing between the accident epicenter and the receptor. Consequently, more realistic accident scenarios are generated than possible with the prevailing techniques. The efficacy of the approach has been illustrated with case studies.

Nearly all the techniques, tools and strategies for preventing accidents in chemical process industry revolve round the question: what would happen if a vessel, a conduit, a controller, or a process suddenly fails leading to an accident?’ To answer this question accidental scenarios are developed and, based on the wisdom of hindsight derived from the post-mortem of past accidents, the damage likely in each scenario is assessed. This information provides the key feedback for quantifying and ‘scaling’ hazards: higher the probability-cum-severity of the likely accident, higher the risk posed by the unit whose failure may cause the accident. In other words, assessment of the likely consequences of a likely accident is one of most common and important steps associated with loss prevention and safety promotion in process industry. In the hitherto used approach it is assumed that the blast wave and heat load generated by an explosion or explosion-cum-fire would travel radically outward with equal intensity in all directions from the accident epicentre. It is also assumed that the intensity of the impact felt by a receptor would only be a function of the receptor's distance from the epicentre but shall be independent of the receptor's direction. In real-life situations, however, the flux of energy, mass and momentum ensuing from an accident would not travel with equal intensity in all directions but would be absorbed or attenuated by different objects lying in its path in different directions. In order to foresee a more plausible picture of the ‘risk contours’ of a likely accident it is necessary to develop a methodology which takes cognizance of the site characteristics likely to influence the accident's impact zone. In this paper the technique of cellular automata (CA) has been used, in all probability for the first time ever, as a basis to develop a new methodology for assessing the consequences of an accident occurring in a chemical process industry. CA was originally developed by von Neumann to model life-like processes but until recently its use was very limited due to its need for expensive computer time. The technique is now experiencing a resurgence as the falling cost-capability ratio of computers has made CA increasingly affordable. In the CA-based methodology presented here, we have treated an industrial accident as an event occurring in a hypothetical square-shaped ‘cell’, surrounded on all sides by other square ‘cells’ of identical area. The grid simulates the accidental site and the model correlates all the cells of the grid with each other on the basis of ‘influencing’ or ‘transition’ functions; these functions, in turn, are governed by the cell characteristics—in other words the composition of the fragment of the site represented by that cell. The accident is modeled to proceed in small but discrete time-steps; in each step the impact of the ‘seed cell’ (the one in which the accident occurs) causes the state of the other cells to change in accordance with the appropriate transition function. It is, therefore, possible to take into account the nature of space that lies between the accident epicentre and the receptor in each direction. As a consequence ‘the impact zone’ of any accident can be forecasted much more accurately than possible hitherto. The applicability of the methodology has been demonstrated with the help of an illustrative case study.

Water quality indices are necessary for resolving lengthy, multi-parameter, water analysis reports into single digit scores. This, in turn, is essential for comparing the water quality of different sources and in monitoring the changes in the water quality of a given source as a function of time and other influencing factors. In this paper we present the computer-automated tool QUALIDEX (water QUALIty inDEX), which has been developed by us to generate and operate water quality indices. Several popular indices--such as the Oregon Water Quality Index developed in the 1970s by Oregon Department of Environmental Quality and later updated in 1995, the Aquatic Toxicity Index developed by Wepener and coworkers for protection of aquatic life at the Olifants river, Kruger National Park, South Africa, the water quality index developed by Dinius in 1987, the Overall Index of Pollution (of surface waters) developed at the National Environmental Engineering Research Institute (NEERI), and the water quality index of the Central Pollution Control Board (CPCB)--have also been added to QUALIDEX in modular form. There is also a New water quality index sub-module which enables the user to generate his or her own index and compare its performance with these well-known indices. The package is also capable of analyzing the variations in the water quality of different sites at different times. The software has been coded in Visual C++ and has been integrated with MS Access database.

A procedure has been developed for extracting volatile fatty acids (VFAs) from water hyacinth (WH) using simple and inexpensive equipment of the type commonly available in the rural households of the third world countries. The VFAs thus extracted were used as feed supplement in cow dung-fed floating-dome biogas digesters. As tens of thousands of such digesters are in operation across the third world, the aim of these studies has been to provide for such digesters feed derived from phytomass, especially for use whenever animal dung is in short supply or is unavailable. The VFA extraction was based on aerobic/facultative degradation of water hyacinth and significant quantities were extracted from each WH charge daily for upto 6 days. When cow-dung slurry was fortified with the VFAs and fed to a conventional biogas digester, it yielded about 22% higher quantity of biogas per unit feed than was obtained from equivalent mass (dry weight basis) of the unfortified cow-dung slurry. The technique developed by us enables phytomass to be utilized as feed supplement in biogas digesters without causing the problems of solids accumulation, frothing and clogging known to be associated with phytomass feed. After VFAs have been extracted from it, the ‘spent’ water hyacinth was vermicomposted and used as soil conditioner-cum-fertilizer.

Litter of the mango (Mangifera indica) tree leaves was composted and then converted into vermicast by the action of the earthworm Eudrilus eugeniae Kinberg. After over nine months of continuous operation the vermireactors with 62.5 animals l(-1) generated approximately 13.6g vermicast per litre of reactor volume (l) per day (d) whereas the reactors with 75 animals l(-1) produced approximately 14.9 g vermicast l(-1) d(-1). This difference in performance of the reactors operating in duplicate at the two different earthworm densities was statistically significant (or = 90% confidence level) for most of the nine-month span. The animals grew well in all reactors, increasing their zoomass by approximately 103% and producing approximately 157 offspring. Not a single of the 1100 animals died during the first four months. In the subsequent five months a total of 122 worms died, representing a loss of approximately 2% per month. We attribute this to the normal process of ageing. The ability of the earthworms to survive, grow and breed in the vermireactors fed with composted mango tree leaves, and a rising trend in vermicast output inspite of the death of a few worms after four months of reactor operation, indicate the sustainability of this type of vermireactors. The studies also indicate that even better vermireactor efficiency may be possible by modifying the reactor geometry. Studies on changes in C:N ratio during composting and vermicomposting revealed that whereas composting helped in lowering the ratio due to loss of carbon in bacterial metabolism, vermicomposting had no such effect on the ratio.

Epigeics, such as Eudrilus eugeniae, Eisenia fetida and Perionyx excavatus are humus-feeder earthworms which, in natural environments, mostly dwell in the humus and leaf litter lying over the top soil and have very shallow borrows. In order to make the most of this characteristic of the epigeics, we have simplified the design of epigeic-based vermireactors by doing away with layers of gravel, sand and soil, normally used for maintaining the other types (anecic and endogeic) of earthworms in the vermireactors. Instead, we have laid a moistened cotton cloth at the bottom of the circular vermireaction tank and have laid the feed over it. This arrangement provides the epigeics with a thin, moisture-rich, layer of solids beneath the humus-like compost used in the reactors as feed. The bottom layer mimics the moist soil below the mulch and humus which the epigeics use for their shallow burrows in natural environments. By doing away with the conventionally used elaborate vermibed, which used to take up ∼5% of the vermireactor volume in conventional systems, we have effectively increased the utilizable fraction of the reactor volume, thereby enabling a much higher feed throughput per litre of the reactor. Six month long operation of the conventional and the modified vermireactors in two concurrently run batches – one operating at low density of E. eugeniae and the other in high-rate mode – revealed that vermicast production per litre of reactor volume in both batches of modified reactors was dramatically higher than the output in the corresponding conventional reactors.

The performance of four species of earthworm––Eudrilus eugeniae, Kinberg, Drawida willsi Michaelsen, Lampito mauritii, Kinberg and Perionyx excavatus, Perrier––born and grown in vermireactors fed with paper waste was studied over six months, in terms of vermicast output per unit feed, production of offspring, and increase in worm zoomass. These were compared with the performance of the previous generation which had been raised to adulthood on cowdung as principal feed before shifting them to vermireactors operating on cowdung-spiked paper waste. The results indicated that except with D. willsi of which the second generation performed only a shade better than the first, there was significant improvement in vermicast output, animal growth, and reproduction in the second generation compared to the first. The results indicated that cowdung-spiked paper waste can be an adequate food for successive generations of earthworms and that reactors can be operated indefinitely on this feed. The results also indicated that the earthworm generations born and raised in vermireactors operated on this feed become better vermiconverters of this feed than the parent earthworms.

Greenbelt is a strip of vegetation for which species of trees and shrubs are scientifically chosen and planted to serve a designated purpose such as control of wind erosion, of dust, of noise etc. In the context of air pollution attenuation, greenbelts must be developed around a source of air pollutant in a manner so as to effectively reduce the pollution caused by that source. Design of effective greenbelts involves consideration of meteorological, physico-chemical, biological, and horticultural aspects relevant to pollutant source and the area where greenbelt has to be established. These authors have recently developed mathematical models for effective design of greenbelts. This paper presents an overview of the methodology based on the models, and describes a case study in which the methodology has been applied to design a greenbelt for a real-life situation.

A process for the production of biogas through the anaerobic digestion (AD) of date palm tree waste (DPTW) was developed. The effects of different substrate pretreatments and operating conditions on the yield of biogas and on the chemical composition of DPTW before and after AD were studied. The best results were obtained using alkali pretreatment, with a particle size of 2 to 5 mm, a C:N ratio of 30:1, a digestion temperature of 40 °C, an initial pH of 7.0, and a volatile solids concentration of approximately 10%. The production of flammable biogas containing up to 50% methane started after about one week of operation and continued for approximately 11 weeks. The highest average biogas yield obtained was 342.2 L gas/kg of volatile solids fed to the digester. The highest maximum and average volumetric biogas production rates obtained were 674.5 and 404.4 L/m3 of digester volume per day, respectively. After digestion, there was up to a 58% reduction in the organic matter content of the substrate. Reductions in the contents of cellulose, hemicellulose, and soluble organic compounds were 68.7, 73.4, and 71.9%, respectively, while the ash and lignin contents remained mostly constant. The remaining sludge contained nutrient minerals and some organic matter which qualifies it as a potential soil fertilizer for crop production.

The viability of vermireactors fed with different proportions of water hyacinth (WH) and cowdung (CD) was assessed over six-month trials. All reactors performed sustainably with a steadily rising vermicast output, worm zoomass, and number of offspring. There was no mortality in any of the reactors. A change in the WH:CD ratios from 4:1 to 6:1 had no discernable impact on the reactor performances. Attempts were also made to improve the efficiency of the reactors in terms of vermicast production per unit time and per unit digester volume. These attempts led to the 'high-rate' vermireactor in which 5.6 times greater vermicast was produced per litre of digester volume per day than in the 'low-rate' reactors. The high-rate vermireactors also performed sustainably, with steady vermicast output, animal growth, and reproduction.

Paper waste, spiked with varying proportions of cowdung, was vermicomposted in `low-rate' and `high-rate' reactors. The former type of reactors had earthworm populations and feed loading rates similar to ones recommended by previous workers. The `high-rate' reactors were operated with 12.5 times higher earthworm densities and feed loading rates. All the reactors were studied for six months to assess the vermicast output, survivability, growth and reproduction of the earthworms – hence the sustainability of the reactors – for long-term, continuous operation. The studies revealed the viability of the high-rate vermireactor concept. The high-rate reactors consistently produced over 6.5 times more castings per unit digester volume with no adverse effect on the earthworm population, as reflected by (a) absence of mortality, (b) consistent growth in worm zoomass, and (c) normal rate of reproduction. The studies also revealed that an increase in the cowdung fraction in the feed from 14.3% to 20% (4:1 paper:cowdung blends to 6:1 blends) had little positive impact on the vermicast output or earthworm health. This indicated that spiking of paper feed with ∼14% cowdung, or perhaps an even smaller fraction, might be adequate to support earthworms in the paper-fed vermireactors.

Trees, shrubs, and other vegetation can absorb and assimilate certain air pollutants if the pollutants are present within tolerable levels. This concept is being increasingly used in developing strips of vegetation, often called ‘greenbelts’ around sources of pollution. But several intricacies are associated with the exercise of effective and optimal designing of greenbelts. The pattern of dispersion of air pollutants, as effected by the density of the gaseous plume and the meteorology of the area, must be studied with great precision because these aspects would determine the location and the geometry of the greenbelt. The species composition in the greenbelt should confirm to the pollutants to be attenuated as to the geoclimatic conditions of the region. Decisions on the tree heights, and the sequence of plantation of trees and other vegetation also similarly require complex inputs. In this paper, the authors have addressed these issues and have presented a set of mathematical models, which may help in the rational and optimal design of greenbelts.

Fault tree analysis (FTA) is based on constructing a hypothetical tree of base events (initiating events) branching into numerous other sub-events, propagating the fault and eventually leading to the top event (accident). It has been a powerful technique used traditionally in identifying hazards in nuclear installations and power industries. As the systematic articulation of the fault tree is associated with assigning probabilities to each fault, the exercise is also sometimes called probabilistic risk assessment. But powerful as this technique is, it is also very cumbersome and costly, limiting its area of application. We have developed a new algorithm based on analytical simulation (named as AS-II), which makes the application of FTA simpler, quicker, and cheaper; thus opening up the possibility of its wider use in risk assessment in chemical process industries. Based on the methodology we have developed a computer-automated tool. The details are presented in this paper.

The global attention has always been focussed on the adverse environmental impacts of conventional energy sources. In contrast nonconventional energy sources, particularly the renewable ones, have enjoyed a ‘clean’ image vis a vis environmental impacts. The only major exception to this general trend has been large hydropower projects; experience has taught us that they can be disastrous for the environment. The belief now is that minihydel and microhydel projects are harmless alternatives. But are renewable energy sources really as benign as is widely believed? The present essay addresses this question in the background of Lovin's classical paradigm, which had postulated the hard (malignant) and soft (benign) energy concepts in the first place. It critically evaluates the environmental impacts of major renewable energy sources. It then comes up with the broad conclusion that renewable energy sources are not the panacea they are popularly perceived to be; indeed in some cases their adverse environmental impacts can be as strongly negative as the impacts of conventional energy sources. The paper also dwells on the steps we need to take so that we can utilize renewable energy sources without facing environmental backlashes of the type we got from hydropower projects.

The three aspects of accidents in chemical process industries which cause most serious damage—explosions, fires, and toxic releases—can all be controlled to some extent if greenbelts are present around the affected industry. We have recently developed and validated a system of methodologies for greenbelt design. In this paper we present the application of these models in designing greenbelts and forecasting their role in cushioning the impact of accidental release of toxic gases. With properly located and designed greenbelts as much as 33% of the accidental release of SO2, 43% of H2S, and 51% of NH3 under stable atmospheric conditions (in which the dispersion is very slow and the release thus has maximum toxic impact) can be absorbed.