Micro-treatment options for components of organic fraction of MSW in residential areas

There is a growing interest in management of MSW through micro-treatment of organic fraction of municipal solid wastes (OFMSW) in many cities of India. The OFMSW fraction is high (>80%) in many pockets within South Indian cities like Bangalore, Chikkamagalur, etc. and is largely represented by vegetable, fruit, packing and garden wastes. Among these, the last three have shown problems for easy decomposition. Fruit wastes are characterized by a large pectin supported fraction that decomposes quickly to organic acids (becomes pulpy) that eventually slow down anaerobic and aerobic decomposition processes. Paper fraction (newsprint and photocopying paper) as well as paddy straw (packing), bagasse (from cane juice stalls) and tree leaf litter (typical garden waste and street sweepings) are found in reasonably large proportions in MSW. These decompose slowly due to poor nutrients or physical state. We have examined the suitability of these substrates for micro-composting in plastic bins by tracking decomposition pattern and physical changes. It was found that fruit wastes decompose rapidly to produce organic acids and large leachate fraction such that it may need to be mixed with leachate absorbing materials (dry wastes) for good composting. Leaf litter, paddy straw and bagasse decompose to the tune of 90, 68 and 60% VS and are suitable for composting micro-treatment. Paper fractions even when augmented with 10% leaf compost failed to show appreciable decomposition in 50 days. All these feedstocks were found to have good biological methane potential (BMP) and showed promise for conversion to biogas under a mixed feed operation. Suitability of this approach was verified by operating a plug-flow type anaerobic digester where only leaf litter gathered nearby (as street sweepings) was used as feedstock. Here only a third of the BMP was realized at this scale (0.18 m³ biogas/kg VS 0.55 m³/kg in BMP). We conclude that anaerobic digestion in plug-flow like digesters appear a more suitable micro-treatment option (2–10 kg VS/day) because in addition to compost it also produces biogas for domestic use nearby.     

Biogas from poultry waste—production and energy potential

The objective of this study was to evaluate the effect of heat treatment on poultry litter with different levels of reutilisation for potential generation of biogas in experimental biodigesters. Chicken litter used was obtained from two small-scale poultry houses where 14 birds m^?2 were housed for a period of 42 days per cycle. Litter from aviary 1 received no heat treatment while each batch of litter produced from aviary 2 underwent a fermentation process. For each batch taken, two biodigesters were set for each aviary, with hydraulic retention time of 35 days. The efficiency of the biodigestion process was evaluated by biogas production in relation to total solids (TS) added, as well as the potential for power generation. Quantified volumes ranged from 8.9 to 41.1 L of biogas for aviary 1, and 6.7 to 33.9 L of biogas for aviary 2, with the sixth bed reused from both aviaries registering the largest biogas potential. Average potential biogas in m³ kg^?1 of TS added were 0.022 to 0.034 for aviary 1 and 0.015 to 0.022 for aviary 2. Energy values ??of biogas produced were calculated based on calorific value and ranged from 0.06 to 0.33 kWh for chicken litter without fermentation and from 0.05 to 0.27 kWh for chicken litter with fermentation. It was concluded that the re-use of poultry litter resulted in an increase in biogas production, and the use of fermentation in the microbiological treatment of poultry litter seems to have negatively influenced production of biogas.     

Determination of nickel, copper, zinc and lead in human scalp hair in Syrian occupationally exposed workers by total reflection X-ray fluorescence

In this study, an attempt has been made to study methane flux and quantification of heavy metals from Municipal Solid Waste (MSW) landfill areas of selected cities in India. During the period of study, the average value of methane flux was estimated from these landfill areas varied from 146–454 mg/m2/h. Methane emission from landfill is of serious environmental global concern as it accounts for approximately 15 percentages of current Greenhouse gas emissions. It has been estimated that methane emission, from landfill areas in the world, in next two decades would be same as that what is emitted from paddy fields presently. Besides, the estimation of methane flux, quantification of some heavy metals was conducted to analyse the suitability of using MSW as compost. The average values for metals were observed to be both within the range of USEPA and Indian standards for MSW disposal in landfill areas and to be used as compost respectively.     

Environmental impact of biomethanogenesis

The environmental impact of biomethanogenesis is related to its ecological role, accumulation and effect as a greenhouse gas, and application in anaerobic digestion for conversion of biomass and wastes to methane and compost. Biological formation of methane is the process by which bacteria decompose organic matter using carbon dioxide as an electron acceptor in the absence of dioxygen or other electron acceptors. This microbial activity is responsible for carbon recycling in anaerobic environments, including wetlands, rice fields, intestines of animals sediments, and manures. The mixed consortium of microorganisms involved includes a unique group of bacteria, the methanogens, which may be considered to be in a separate kingdom based on genetic and phylogenetic variance from all other life forms. Because methane is a significant and increasing greenhouse gas, its source fluxes and their potential reduction are of concern. Biomethanogenesis may be harnessed for reduction of wastes and conversion of renewable resources to significant quantities of substitute natural gas which could mitigate carbon dioxide and other pollutants related to use of fossil fuels.     

The potential of biogas production from municipal solid waste in a tropical climate

The objective of this study was to estimate the potential of organic municipal solid waste generated in an urban setting in a tropical climate to produce biogas. Five different categories of wastes were considered: fruit waste, food waste, yard waste, paper waste, and mixed waste. These fractions were assessed for their efficiency for biogas production in a laboratory-scale batch digester for a total period of 8 weeks at a temperature of 15–30 °C. During this period, fruit waste, food waste, yard waste, paper waste, and mixed waste were observed to produce 0.15, 0.17, 0.10, 0.08, and 0.15 m³ of biogas per kilogram of volatile solids, respectively. The biogas produced and caloric value of each feedstock was in the range of 1.25?×?10^?3 m³ (17 kWh)/cap/day (paper waste) to 15?×?10^?3 m³ (170 kWh)/cap/day (mixed waste). Paper waste produced the least (<1×10^?3(<17.8 kWh)/cap/day), and mixed waste produced the highest methane yield (10?×?10^?3 m³ (178 kWh)/cap/day). Thus, mixed waste was found to be more efficient than other feedstocks for biogas and methane production; this was mainly related to the better C/N ratio in mixed waste. Taking the total waste production in Jimma into account, the total mixed organic solid waste could produce 865?×?10³ m³ (5.4 m³/capita) of biogas or 537?×?10³ m³ (3.4 m³/capita) of methane per year. The total caloric value of methane production potential from mixed organic municipal solid waste was many times higher than the total energy requirement of the area.     

Leachate from market refuse and biomethanation study

The market place is considered to be an important centre of daily life of campus community. In India, as in Europe and the USA, other forms of shopping have emerged significantly and now predominate, for instance department stores and supermarkets. Though, it is suffered from poor waste management, but the place could be a potential source for obtaining non-conventional energy. The present study examined the quality of market waste management of the Indian Institute of Technology Campus along with the feasibility of biogas production from leachate generated in the waste. Solid wastes from different storage locations of the market place were collected and analyzed. The characteristics of solid wastes were found to be degradable in nature. The wastes, composed of 85% of vegetable origin, were placed in a container and water was added to to generate leachate. The self-purification efficiency of leachate was also studied in the Indian environment and compared with research findings in the USA under an identical moisture application rate. Leachate characterization was investigated both under saturated and submerged conditions. The treatability of leachate was studied in a laboratory-scale up-flow anaerobic filter with hollow burnt clay rings as packing media. It was observed that 4,000–6,000 mg/l would be the optimum range of inlet chemical oxygen demand (COD) concentration for leachate treatment because of the inhibitory effect of ammonia, sulphide, volatile fatty acids and toxic metals in high concentrations at higher strengths of leachate. The gas production rate was found to be at a maximum at 38°C and containing 70–75% methane. From experimental data, it was revealed that 83% COD was removed with input COD concentration of 5,475 mg/l at 2 days hydraulic retention time with biogas yield coefficients of 0.61. The present study also investigated the removal efficiency of chloride, ammonia, sulphide and nitrate.     

Bacteria Associated with Degradation of Wastes from Rubber Processing Industry

An investigation of bacteria found in rubber processing wastes was carried out. Rubber wastes which include effluents from washing tanks and natural rubber waste serum (NRWS) were obtained from Greenpark Rubber Industries Limited, Umutu, Delta State, Nigeria. Five bacterial species were isolated from the wastes. These include Arthrobacter sp., Bacillus sp., Lactobacillus sp., Psuedomonas sp. and Streptococcus sp. Apart from these a number of coliforms were also encountered. Arthrobacter sp. was found to be the dominant species and its potential to utilize rubber hydrocarbon was determined. It was found that the growth of Arthrobacter in both effluent and NRWS was related to pH with the highest growths recorded at pH of 8.5 and 7.5 for effluent and NRWS respectively. It was also found that at controlled pH of 7.5 in NRWS, the growth of Arthrobacter was consistent and was accompanied by a reduction in biological oxygen demand (BOD) which was the the main index for measuring pollution strength of the wastes. It is therefore being recommended that rubber wastes be treated with Arthrobacter under controlled pH to reduce their pollution potentials before disposal. It is however suggested that a combined biological treatment using both Arthrobacter and Mucor as was earlier suggested be used. It is also recommended that chemical flocculants should be used to remove suspended solids in the effluent. A combination of these two cheap methods will go a long way in alleviating the problems of pollution caused by rubber effluents from some tropical rubber processing factories.     

Distribution and availability of trace elements in municipal solid waste composts

Trace element contamination is one of the main problems linked to the quality of compost, especially when it is produced from urban wastes, which can lead to high levels of some potentially toxic elements such as Cu, Pb or Zn. In this work, the distribution and bioavailability of five elements (Cu, Zn, Pb, Cr and Ni) were studied in five Spanish composts obtained from different feedstocks (municipal solid waste, garden trimmings, sewage sludge and mixed manure). The five composts showed high total concentrations of these elements, which in some cases limited their commercialization due to legal imperatives. First, a physical fractionation of the composts was performed, and the five elements were determined in each size fraction. Their availability was assessed by several methods of extraction (water, CaCl(2)-DTPA, the PBET extract, the TCLP extract, and sodium pyrophosphate), and their chemical distribution was assessed using the BCR sequential extraction procedure. The results showed that the finer fractions were enriched with the elements studied, and that Cu, Pb and Zn were the most potentially problematic ones, due to both their high total concentrations and availability. The partition into the BCR fractions was different for each element, but the differences between composts were scarce. Pb was evenly distributed among the four fractions defined in the BCR (soluble, oxidizable, reducible and residual); Cu was mainly found in the oxidizable fraction, linked to organic matter, and Zn was mainly associated to the reducible fraction (iron oxides), while Ni and Cr were mainly present almost exclusively in the residual fraction. It was not possible to establish a univocal relation between trace elements availability and their BCR fractionation. Given the differences existing for the availability and distribution of these elements, which not always were related to their total concentrations, we think that legal limits should consider availability, in order to achieve a more realistic assessment of the risks linked to compost use.     

Evaluation of Pb (II) biosorption utilizing sugarcane bagasse colonized by <Emphasis Type="Italic">Basidiomycetes</Emphasis>

The contamination of water resources by metallic ions is a serious risk to public health and the environment. Therefore, a great emphasis has been given to alternative biosorption methods that are based on the retention of aqueous-solution pollutants; in the last decades, several agricultural residues have been explored as low-cost adsorbent. In this study, the ability of Pb (II) biosorption using sugarcane bagasse modified by different fungal species was evaluated. The presence of carbonyl, hydroxyl, and carboxyl groups in the biosorbent was observed by spectroscopy in the infrared region. By scanning electron microscopy, changes in the morphology of modified material surfaces were observed. The highest adsorption capacity occurred at pH 5.0, while the shorter adsorbate-adsorbent equilibrium was at 20 min, and the system followed the pseudo-second-order model. The maximum biosorption in isotherms was found at 58.34 mg g^?1 for modified residue by Pleurotus ostreatus U2-11, and the system followed the Langmuir isotherm. The biosorption process was energetically spontaneous with low desorption values. This modification showed great potential for filters to remove Pb (II) and provide the preservation of water resources and animal health.     

Copper and Zinc in a paddy field and their potential ecological impacts affected by wastewater from a lead/zinc mine, P. R. China

As well known, at normal levels, copper and zinc are essential micronutrients for plants, animals, and humans. However, excessive Cu and Zn are toxic and disturb a wide range of biochemical and physiological processes. Using Atomic Absorption Spectrophotometer (AAS; Perkin-Elmer 3030, USA), soil and rice plant (Oryza sativa L.) samples collected from a paddy field in Lechang lead-zinc mine area, Guangdong Province, China were analyzed and their potential ecological impacts to local human and livestock were evaluated. The results showed that the paddy soils were contaminated with Cu and Zn. Both metals in soils had low bio-available fractions for paddy plants, animal and human by three chemically analytical techniques. Generally, were concentrations of copper and zinc root > straw > stalk > grain with hull > grain without hull (i.e. unpolished rice) and in the normal ranges indicating no ecological risk for local livestock and residents. All positive correlation coefficients, however, between heavy metals in rice plant and total, exchangeable (step 1 in Tessier's method established in 1979) and DTPA-extractable fractions in soils were found in this study indicating that elevated heavy metal in soils would increase long-term exposition and possible consequence of ecological hazard through food chains.     

Mitigation Strategy to Contain Methane Emission from Rice-Fields

Methane is primarily a biogenic gas, which is implicated in global climate change. Among all the sources of methane emission, paddy fields form the most dominant source. An experiment was conducted with a common paddy crop (Oryza sativa var. Vishnuparag) by amending the soils with different organic manures and biofertilizers with a view to find out an inexpensive strategy to mitigate methane emission from the rice-fields. The results revealed that there was a seasonal change in the CH₄ flux, registering a peak at heading stage in all treatments. The application of rice straw before flooding and the biofertilizer after flooding enhances CH₄ efflux from the rice-fields significantly, while composts of cowdung and leaves did not stimulate CH₄ production and, rather, decreased CH₄ fluxes. As soil pH and temperature were optimum for methanogenesis, it was likely that the organic C and the redox potential mainly modulated methane production and its emission through rice plants.     

Enhanced uptake of heavy metals in municipal solid waste compost by turfgrass following the application of EDTA

Enhancement of multiple heavy metal uptake from municipal solid waste (MSW) compost by Lolium perenne L. in a field experiment was investigated with application of EDTA. EDTA was added in solution at six rates (0–30 mmol kg^???1) after 50 days of plant growth. Two weeks later, plants were harvested for the first crop and then all the turfgrasses were mowed. After another 30 days of growth, EDTA was added again at above six rates to the corresponding sites and the second crop was harvested 2 weeks later. The results showed that EDTA significantly increased heavy metal accumulation in both crops of L. perenne. For the first crop, the concentrations of Mn, Ni, Cd, and Pb in the shoots increased remarkably with increasing EDTA supply, peaked at 25 mmol kg^???1 EDTA, and shoots of 0–5 cm height (shoots from medium surface to 5 cm height) had higher metal concentrations than 5–10 cm and >10 cm shoots. The highest concentration of Mn, Ni, Cd, and Pb was 2.3-, 2.3-, 2.6-, and 3.2-fold, respectively, in 0–5 cm shoots higher than control. For the second crop, the concentrations of Mn, Cu, and Pb in shoots were, in general, less than those in the first crop. However, the second crop was significantly higher (P?< 0.05) than the first crop in dry biomass, so the total amount of metals removed by the second crop was more than the first crop. In addition, EDTA significantly increased the translocation ratios of most heavy metals from roots to shoots. For the first crop, 38% of the total Zn, 51% of Cd, 49% of Pb, 60% Mn, 55% Ni, and 45% Cu taken up by the plant was translocated in the shoots of 0–5 cm height. Turfgrass would have potential for use in remediation of heavy metals in MSW compost or contaminated soils.     

Life cycle assessment of traditional and alternative bricks: A review

Life cycle assessment (LCA) is a solid tool to assess the potential environmental impacts in construction industry, an important material in this industry is the brick, along time several traditional and alternative bricks were developed and assessed environmentally by LCA. The purpose of this article is to review the literature related to LCA of bricks, responding important topics to characterize and guide future studies. Out of Traditional Bricks (TB), there are Alternative Bricks with Organic (ABO) and Inorganic (ABI) additives, that use wastes from several industries and differ of TB in the omission of firing for a stabilization process, however, to omit firing is hard and stabilization still needs further improvements. The principal system boundaries and tools for LCA were also reviewed. Regarding the most present impact categories, they were: Climate change (CC), Human Toxicity (HT) and Freshwater Ecotoxicity (FE), in every category, production is the stage of highest impact, and in the productive process, drying and burning processes have the highest potential impacts. Future searches could continue to study on new materials (wastes) for development of new ABO and ABI, to quantify the benefits of reusing wastes, and to study, either the replacement of firing with stabilizing processes, or the use of biomass as fuel source in firing, and to develop studies in different countries to create national datasets that will make future studies more representative.     

Distribution patterns of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in sediments of the Xiangjiang River, China

We investigated the occurrence and distribution patterns of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in six sediment samples from the Xiangjiang River, Hunan Province, People’s Republic of China. Total concentrations of PCDD/Fs ranged from 876 to 497,759 (mean 160,766) ng/kg dw, the highest of which exceeded that have ever been reported for sediment samples. World Health Organization total toxicity equivalent (WHO-TEQ) concentrations in three out of six samples were significantly higher than the guidance level (21.5?ng WHO-TEQ/kg dw) suggested by Canadian Sediment Quality Guideline. A predominance of octachlorodibenzo-p-dioxin (OCDD) was observed with an average contribution of 90.8% to the total PCDD/F concentrations, while 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) was the major contributor to the PCDD/F WHO-TEQ concentrations in most of the sites. Such high levels of OCDD and HpCDD may be attributed to the presence of PCP/PCP-Na pollution, although MB-WW, agricultural straw open burning, and boilers–hazardous wastes were also the potential sources of PCDD/Fs. This is the first report for the concentrations and congener profiles of PCDD/Fs in sediment samples from the Xiangtan, Zhuzhou, and Changsha sections of the Xiangjiang River, providing scientific evidence for establishing priorities to reduce ecological risks posed by PCDD/Fs in the rapidly developing areas of Hunan Province and elsewhere.     

Non-radiological contaminants from uranium mining and milling at Ranger,Jabiru, Northern Territory,Australia

Protection from the hazards from radioactivity is of prime importance in the management of uranium mine and mill wastes. Such wastes also contain non-radiological contaminants (heavy metals, acids and neutralising agents) which give rise to potential long-term health and environmental hazards and short-term hazards to the aquatic ecosystem, e.g. as a result of release of waste water. This study seeks to identify non-radiological contaminants (elements) transferred to waste water at the Ranger uranium mine/mill complex at Jabiru, which are likely to hazardous to the aquatic environment. The two principal sources of contaminants are:

1. ore and waste rock mobilised from mining; and
2. process reagents used in the milling and mineral extraction process.

These substances may or may not already be present in the natural environment but may lead to deleterious effects on the aquatic environment if increased above threshold levels. Rhenium, derived from the ore body, was found to be significantly enriched in waste water from Ranger, indicating its suitability as an indicator element for water originating from the mining and milling process, but only uranium, likewise derived from the ore, and magnesium, manganese and sulfur (as sulfate) from the milling process were found to be significant environmental contaminants.     

The potential for anaerobic mineralisation of hydrocarbon constituents of oily drill cuttings from the North Sea seabed

The potential for natural attenuation of hydrocarbons in oily drill cuttings from the seabed beneath a North Sea oil platform was investigated. The study focused on the anaerobic degradation of n-hexadecane, n-octacosane and naphthalene using additions of 14C-labelled analogues to drill cuttings samples and was conducted under realistic seabed conditions (except pressure) over an 11-month period. No mineralisation of naphthalene was detected over this time period and mineralisation of octacosane represented only 0.5-1.5% of the added label. In contrast, mineralisation of hexadecane was 10-49% after 11 months of incubation. Selective inhibition of key functional bacterial groups revealed the key role of both sulfate reduction and methanogenesis in the degradation process. This study demonstrates the potential for natural attenuation of at least some hydrocarbon constituents of oily drill cuttings under realistic environmental conditions and highlights the involvement of a wide functional consortium in the natural attenuation process.     

Preconcentration technique for the determination of trace elements in natural water samples by ICP-AES

A procedure was developed for the determination of Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) after preconcentration on a morpholine dithiocarbamate (mor-DTC) supported by bagasse (Saccharam aphisinaram). The sorbed elements were subsequently eluted with 4,M HNO₃ and the acid eluates were analysed by ICP–AES. The influence of various parameters such as pH, flow rate of sample, eluent concentration, volume of the sample and volume of eluent were investigated to enhance the sensitivity of the present method. A 20,mL disposable syringe served as preconcentration column. Under the optimal conditions Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in aqueous sample was concentrated about 100-fold. The sorption recoveries of elements were higher than 99.6%. The method is also applied for the analysis of natural and spiked water samples.     

Modeling nonlinearly transient zero-order bioreduction and transport of Cr(VI) in groundwater

Cr(VI) contamination of soil and groundwater is considered a major environmental concern. Bioreduction of Cr(VI) to Cr(III) can be considered a potentially effective technology in remediating Cr(VI) contaminated sites. Shewanella oneidensis MR-1 (MR-1) is one of the bacteria capable of reducing Cr(VI) to Cr(III) under anaerobic conditions. The kinetics of Cr(VI) reduction by MR-1 is defined by the dual-enzyme kinetic model which is nonlinear, transient, and zero-order. Existing transport models are not designed to simulate such reaction kinetics. The objective of this paper is to present a Petrov–Galerkin finite element model (PGFEM) to simulate transport and bioreduction of Cr(VI), by MR-1, in groundwater. The model developed is unconditionally stable and provides oscillation free accurate results for a wide range of Peclet number (Pn) and Courant number (Cn).     

An assessment of tree health and trace element accumulation near a coal-fired generating station, Manitoba, Canada

A forest health assessment was performed in stands dominated by bur oak and trembling aspen to study the potential effects of airborne emissions from a 132 MW coal-fired station. Forty-two stands were sampled within a 16-km radius of the station for both foliar stress symptoms and trace element toxicology. The concentrations of tracer elements (As, Ba, Sr, and V) in the leaf litter were not spatially congruent with airborne emission deposition models (except Ba, which showed elevated levels immediately SE of the station), nor were they at phytotoxic levels. Elemental concentrations were significantly related to soil parameters including organic matter and texture. No patterns were found in forest health along directional or distance gradients from the generating station. Trembling aspen stands demonstrated little decline in general, but three of the 19 bur oak plots, all located on thin sandy soils developed on calcareous till, demonstrated branch dieback. In addition to poor soil conditions, two of these sites also had high water tables, and exhibited tree mortality. The bur oak decline did not appear to be related to emissions from the station, but is suspected to be a result of poor site quality, with urban development as a confounding factor.     

Distribution and sources of polycyclic aromatic hydrocarbons in Wuhan section of the Yangtze River, China

Polycyclic aromatic hydrocarbons (PAHs) are important organic contaminants with great significance for China, where coal burning is the main source of energy. In this study, concentrations, distribution between different phases, possible sources and eco-toxicological effect of PAHs of the Yangtze River were assessed. PAHs in water, suspended particulate matters (SPM) and sediment samples at seven main river sites, 23 tributary and lake sites of the Yangtze River at the Wuhan section were analyzed. The total concentrations of PAHs in the studied area ranged from 0.242 to 6.235 μg/l in waters and from 31 to 4,812 μg/kg in sediment. The average concentration of PAHs in SPM was 4,677 μg/kg, higher than that in sediment. Benzo(a)pyrene was detected only at two stations, but the concentrations were above drinking water standard. The PAHs level of the Yangtze River was similar to that of some other rivers in China but higher than some rivers in foreign countries. There existed a positive relationship between PAHs concentrations and the TOC contents in sediment. The ratio of specific PAHs indicated that PAHs mainly came from combustion process, such as coal and wood burning. PAHs may cause potential toxic effect but will not cause acute biological effects in sedimentary environment of the Wuhan section of the Yangtze River.