Dry reforming of methane to syngas: a potential alternative process for value added chemicals—a techno-economic perspective

During the past decade, there has been increasing global concern over the rise of anthropogenic CO₂ emission into the Earth’s atmosphere (J Air Waste Manage Assoc 53:645–715, 2003). The utilization of CO₂ to produce any valuable product is need of the hour. The production of syngas from CO₂ and CH₄ seems to be one of the promising alternatives in terms of industrial utilization, as it offers several advantages: (a) mitigation of CO₂, (b) transformation of natural gas and CO₂ into valuable syngas, and (c) producing syngas with H₂/CO ratio 1 which may further be used for the production of valuable petrochemicals (J Air Waste Manage Assoc 53:645–715, 2003). A conceptual design for the production of synthesis gas by dry reforming of methane is presented here. An economic assessment of this process with an integrated methanol production section as a case was conceptualized and compared with the conventional steam methane reforming route to produce methanol. The economic study indicated that dry reforming of natural gas/methane is a competitive process with lower operating and capital costs in comparison with steam reforming assuming negligible cost of CO₂ import.     

Feasibility study of rainwater harvesting system in Sylhet City

In rural areas in Bangladesh, groundwater is the principal source of water supply. This underground water is available in considerable amount in shallow aquifers. It is free from pathogenic microorganisms and hence water-borne diseases. In plain lands, other than hilly areas, water supply to 97% rural population comes from tube-wells, which is regarded to be a phenomenal achievement in preserving public health. Besides, a dependable water supply system all throughout the country is offset by two factors: (a) high salinity in surface plus groundwater in coastal areas; (b) want of suitable groundwater aquifers in hilly areas and the high cost of setting up tube-wells due to deep underground water table and stony layers. However, presence of arsenic in underground water now poses a serious threat to the success once made in water supply by setting up of manually operated tube-wells in the village areas—the achievement is now on the brink of total collapse. In about 61 districts out of 64, presence of arsenic exceeds a quantity of 0.05 mg/1, a permissible limit as per Bangladeshi water quality standard. Harvesting rainwater can be a pragmatic solution to this problem, which is common in many places in Sylhet especially in the hilly areas on the north eastern part of the city. This can be an alternative source of drinking water because of availability of rainwater from March to October. Heavy rain occurs from end of May till mid September, which is commonly known as the rainy season. This paper focuses on the possibility of harvesting rainwater in rural communities and thickly populated urban areas of Sylhet. It also demonstrates the scopes of harvesting rainwater using simple and low-cost technology. With setting up of a carefully planned rainwater storage tank, a family can have all of its drinking water from rain. Planned use of rainwater through rainwater harvesting in the roof catchments may fulfill the entire annual domestic water demand of a family in the rural areas of Bangladesh.     

Generation, storage, collection and transportation of municipal solid waste--a case study in the city of Kathmandu, capital of Nepal

Solid waste management (SWM) services have consistently failed to keep up with the vast amount of solid waste produced in urban areas. There is not currently an efficient system in place for the management, storage, collection, and transportation of solid waste. Kathmandu City, an important urban center of South Asia, is no exception. In Kathmandu Metropolitan City, solid waste generation is predicted to be 1091 m(3)/d (245 tons/day) and 1155 m(3)/d (260 tons/day) for the years 2005 and 2006, respectively. The majority (89%) of households in Kathmandu Metropolitan City are willing to segregate the organic and non-organic portions of their waste. Overall collection efficiency was 94% in 2003. An increase in waste collection occurred due to private sector involvement, the shutdown of the second transfer station near the airport due to local protest, a lack of funding to maintain trucks/equipment, a huge increase in plastic waste, and the willingness of people to separate their waste into separate bins. Despite a substantial increase in total expenditure, no additional investments were made to the existing development plan to introduce a modern disposal system due to insufficient funding. Due to the lack of a proper lining, raw solid waste from the existing dumping site comes in contact with river water directly, causing severe river contamination and deteriorating the quality of the water.     

Residual fate and persistence of endosulfan (50 WDG) in Bengal gram (Cicer arietinum)

A detailed study has been presented on heavy metal content of the Iture Estuary. Waters of the Sorowie and Kakum rivers that supply water into the Estuary were investigated to ascertain heavy metal pollution levels due to anthropogenic activities. Concentration s of Cd, Zn, Se and Pb were measured. The study shows pre-occupying pollution levels that constitute a threat to both terrestrial and aquatic ecosystems. The abundance of metals in the Estuary is in the order Zn > Pb > Cd > Se. The level of Cd in the Iture Estuary ranged between 0.011 mg/l and 0.041 mg/l while Se was in the range 0.018 mg/l to 0.029 mg/l, Pb 0.020 mg/l to 0.075 mg/l and Zn 0.040 to 2.45 mg/l. The impact of contaminated water from the Sorowie River on the Iture Estuary was outstanding and the study points out the importance of the Sorowie River as a primary pollution source to the Iture Estuary. The pollution of the Iture Estuary was found to be connected to human activities in its catchments.     

Biomass fuel use,burning technique and reasons for the denial of improved cooking stoves by Forest User Groups of Rema-Kalenga Wildlife Sanctuary,Bangladesh

ABSTRACT

This study investigates the structural linkages of product quality, corporate image, store image, and price on customer satisfaction and loyalty towards green products usage in Malaysia. The research used structural equation modelling technique via AMOS 21.0 computer program for data analysis across a sample of 200 university students who applies a green lifestyle, such as purchasing green products which are referring to only retail goods, using recyclable products, and ozone-free products. Empirical analysis divulged that product quality followed by corporate image, store image, and product price jointly affected customer satisfaction in using green products. They are highly concerned that the green store provides a variety of good quality products with good value for money. Marketers should aggressively promote the identification of green products and overcome the problem of just noticeable difference between green product and non-green product among consumers for business sustainability. Empirical findings provide valuable insights to put forth in outlining effective marketing strategies that widen the marketers’ understanding of consumer behaviour in using green products with regard to their satisfaction and loyalty levels from the perspective of product quality, corporate image, store image, and product prices in Malaysia markets.     

An Analysis of the Indoor Air Quality and Mould Growth in a Multi-zone Building

The effects of poor indoor air quality and mould growth in working environment are major problems in built environment, and there is a need to look for improvement of the health, comfort and productivity of the building occupants. Airborne mould sampling studies were conducted in a reference building located in Rockhampton, Central Queensland, Australia. Both indoor culturable and mould spore levels were observed. It was found through the indoor–outdoor ratios of the species that indoor concentrations are mostly related to the outdoor mould levels. The moulds differ in their relative humidity and temperature requirements to support surface growth. Indoor humidity has a significant effect on occupants comfort, perceived air quality, occupants’ health, building durability, emissions and energy efficiency. Practical hygrothermal simulation models are employed to analyse the combined heat and moisture behaviour within the built environment. A review of the current modelling options available to predict building performance based on energy and mass transport simulation is presented, and then a case study is presented with the assessment of indoor built environment to avoid mould problem.     

Catalytic activities of ultra-small β-FeOOH nanorods in ozonation of 4-chlorophenol

We report the catalytic properties of ultra-small β-FeOOH nanorods in ozonation of 4-chlorophenol (4-CP). XRD, TEM, EDS, SAED, FTIR and BET were used to characterize the prepared material. Interaction between O₃ and β-FeOOH was evident from the FTIR spectra. The removal efficiency of 4-CP was significantly enhanced in the presence of β-FeOOH compared to ozone alone. Removal efficiency of 99% and 67% was achieved after 40 min in the presence of combined ozone and catalyst and ozone only, respectively. Increasing catalyst load increased COD removal efficiency. Maximum COD removal of 97% was achieved using a catalyst load of 0.1 g/100 mL of 4-CP solution. Initial 4-CP concentration was not found to be rate limiting below 2 × 10^− 3 mol/L. The catalytic properties of the material during ozonation process were found to be pronounced at lower initial pH of 3.5. Two stage first order kinetics was applied to describe the kinetic behavior of the nanorods at low pH. The first stage of catalytic ozonation was attributed to the heterogeneous surface breakdown of O₃ by β-FeOOH, while the second stage was attributed to homogeneous catalysis initiated by reductive dissolution of β-FeOOH at low pH.     

Fuzzy rule-based modelling for human health risk from naturally occurring radioactive materials in produced water

Produced water, discharged from offshore oil and gas operations, contains chemicals from formation water, condensed water, and any chemical added down hole or during the oil/water separation process. Although, most of the contaminants fall below the detection limits within a short distance from the discharge port, a few of the remaining contaminants including naturally occurring radioactive materials (NORM) are of concern due to their bioavailability in the media and bioaccumulation characteristics in finfish and shellfish species used for human consumption. In the past, several initiatives have been taken to model human health risk from NORM in produced water. The parameters of the available risk assessment models are imprecise and sparse in nature. In this study, a fuzzy possibilistic evaluation using fuzzy rule based modeling has been presented. Being conservative in nature, the possibilistic approach considers possible input parameter values; thus provides better environmental prediction than the Monte Carlo (MC) calculation. The uncertainties of the input parameters were captured with fuzzy triangular membership functions (TFNs). Fuzzy if-then rules were applied for input concentrations of two isotopes of radium, namely (226)Ra, and (228)Ra, available in produced water and bulk dilution to evaluate the radium concentration in fish tissue used for human consumption. The bulk dilution was predicted using four input parameters: produced water discharge rate, ambient seawater velocity, depth of discharge port and density gradient. The evaluated cancer risk shows compliance with the regulatory guidelines; thus minimum risk to human health is expected from NORM components in produced water.     

Complete degradation of di-n-octyl phthalate by Gordonia sp. strain Dop5

The present study describes the assimilation of di-n-octyl phthalate by an aerobic bacterium, isolated from municipal waste-contaminated soil sample utilizing di-n-octyl phthalate as the sole source of carbon and energy. The isolate was identified as Gordonia sp. based on the morphological, nutritional and biochemical characteristics as well as 16S rRNA gene sequence analysis. A combination of chromatographic and spectrometric analyses revealed a complete di-n-octyl assimilation pathway. In the degradation process, mono-n-octyl phthalate, phthalic acid, protocatechuic acid and 1-octanol were identified as the degradation products of di-n-octyl phthalate. Furthermore, phthalic acid was metabolized via protocatechuic acid involving protocatechuate 3,4-dioxygenase while 1-octanol was metabolized by NAD⁺-dependent dehydrogenases to 1-octanoic acid, which was subsequently degraded via β-oxidation, ultimately, leading to tricarboxylic acid cycle intermediates. Apart from phthalic acid and 1-octanol metabolizing pathway enzymes, two esterases, di-n-octyl phthalate hydrolase and mono-n-octyl phthalate hydrolase involved in di-n-octyl phthalate degradation were found to be inducible in nature. This is the first report on the metabolic pathway involved in the complete degradation of di-n-octyl phthalate by a single bacterial isolate, which is also capable of efficiently degrading other phthalate esters of environmental concern having either shorter or longer alkyl chains.