Pesticide Residues in Bovine Milk from a Predominantly Agricultural State of Haryana, India

One hundred forty seven samples of bovine milk were collected from 14 districts of Haryana, India during December 1998–February 1999 and analysed for the presence of organochlorine pesticide (OCPs) residues. ∑HCH, ∑DDT, ∑endosulfan and aldrin were detected in 100%, 97%, 43% and 12% samples and with mean values of 0.0292, 0.0367, 0.0022 and 0.0036 μg/ml, respectively. Eight percent samples exceeded the maximum residue limit (MRL) of 0.10 mg/kg as recommended by WHO for ∑HCH, 4% samples of 0.05 mg/kg for α-HCH, 5% samples of 0.01 mg/kg for γ-HCH, 26% samples of 0.02 mg/kg for β-HCH as recommended by PFAA and 24% samples of 0.05 mg/kg as recommended by FAO for ∑DDT. Concentrations of β-HCH and p,p′-DDE were more as compared to other isomers and metabolites of HCH and DDT.     

Comparative evaluation of a bioluminescent bacterial assay in terrestrial ecotoxicity testing

Despite the widespread and successful use of luminescence-based bioassays in water testing, their applications to soils and sediments is less proven. In part this is because such bioassays have mainly been carried out in an aqueous-based medium and, as such, favour contaminants that are readily water-soluble. In this study, aqueous solutions and soils contaminated with heavy metals (HM), polar organic contaminants and hydrophobic organic contaminants (HOCs) were tested using a range of luminescence-based bioassays (Vibrio fischeri, Escherichia coli HB101 pUCD607 and Pseudomonas fluorescens 10586r pUCD607). For the first two chemical groups, the assays were highly reproducible when optimised extraction procedures were employed but for HOCs the bioassay response was poor. Quantitative structure-activity relationships (QSARs) obtained from aqueous solutions had a linear response although correlation for the chemicals tested using bacterial bioassays was significantly less sensitive than that of sublethal tests for Tetrahymena pyriformis. Bacterial and Dendrobaena veneta bioassay responses to extracts from HM amended soils showed that a clear relationship between trophic levels could be obtained. There is no doubt that the wide range of bioluminescent-based bioassays offers complementary applications to traditional testing techniques but there is a significant need to justify and optimise the extraction protocol prior to application.     

Pyrolysis of mixtures of sewage sludge and manure: a comparison of the results obtained in the laboratory (semi-pilot) and in a pilot plant

A pilot-scale pyrolysis process was carried out for the treatment of a mixture of two types of waste, sewage sludge and cattle manure, comparing the results with others obtained under laboratory conditions (semi-pilot scale). The aim of this study was to obtain the energetic valorization of the products. Owing to the specific characteristics of the plant, two products were obtained from the process: gas and carbonized solid. As no liquid fraction was obtained, the gas fraction is a greater percentage made up of both condensable and non-condensable compounds, which were obtained separately at the laboratory scale. The pilot plant was designed so that the gases produced by thermolysis were burnt continuously in a combustion chamber, while the carbonized fraction was fed in batches for co-combustion. To determine composition and combustion ability, the gas and solid products from the pilot process were characterized by chromatographic analysis of the gaseous fraction and chemical analysis and programmed-temperature combustion of the carbonized solid. The composition of the combustion gases, rich in light hydrocarbons, and the carbon present in the carbonized fraction enable the energetic valorization of these products. The combustion gases were subjected to a cleaning process and their composition analysed twice: before and after the gas cleaning treatment. The study led to a positive assessment of the possible use of the process products as fuel, provided that the combustion gases are treated. As most of the sulphur and chlorine from the original waste are mainly concentrated in the solid fraction, the use of char as a fuel will depend on the effectiveness of clean-up techniques for combustion gases. During gas cleansing, neutralizing with sodium bicarbonate proved effective, especially for the acidic compounds HCl, HF and SO(2).     

Review of state of the art methods for measuring water in landfills

In recent years several types of sensors and measurement techniques have been developed for measuring the moisture content, water saturation, or the volumetric water content of landfilled wastes. In this work, we review several of the most promising techniques. The basic principles behind each technique are discussed and field applications of the techniques are presented, including cost estimates. For several sensors, previously unpublished data are given. Neutron probes, electrical resistivity (impedance) sensors, time domain reflectometry (TDR) sensors, and the partitioning gas tracer technique (PGTT) were field tested with results compared to gravimetric measurements or estimates of the volumetric water content or moisture content. Neutron probes were not able to accurately measure the volumetric water content, but could track changes in moisture conditions. Electrical resistivity and TDR sensors tended to provide biased estimates, with instrument-determined moisture contents larger than independent estimates. While the PGTT resulted in relatively accurate measurements, electrical resistivity and TDR sensors provide more rapid results and are better suited for tracking infiltration fronts. Fiber optic sensors and electrical resistivity tomography hold promise for measuring water distributions in situ, particularly during infiltration events, but have not been tested with independent measurements to quantify their accuracy. Additional work is recommended to advance the development of some of these instruments and to acquire an improved understanding of liquid movement in landfills by application of the most promising techniques in the field.     

Chemical and biological characterization of slaughterhouse wastes compost

The chemical and biological properties of compost made from yard trimmings (YT) composted alone or mixed with slaughterhouse wastes (SHW) were evaluated in seven phases. Mixtures were weighed in a 2:1 proportion (YT:SHW) and placed in composting bins (0.91 m2). Temperature was recorded to determine the time (d) needed to reach the first (1HC) and second heat cycles (2HC). Composting characteristics were measured at 0 d, at the peak of the 1HC and 2HC, and at maturation (0, 20, 50 and 70 d). During 1HC, bacterial isolates were cultivated in both treatments and identified using the Biolog System. Chemical composition was statistically analyzed using a 2 (layers of SHW)x7 (composting phases) factorial arrangement of treatments with the ANOVA procedure of SAS. The pH was neutral for YT and ranged from 7.41 to 6.82 for SHW throughout the process. There was a decrease in organic matter (OM) and carbon (C), and a relative increase in nitrogen (N) in both treatments. At 70 d of maturation, C:N values were similar between treatments, but lower (P>0.05) than the initial values. Final N concentration was higher (P>0.05) for the treatment with SHW. Only the SHW treatment exhibited thermophilic temperatures. At the 1HC in both treatments, different populations of bacteria responsible for the breakdown of OM were identified showing an active heterogeneous population. The presence of pathogenic microorganisms was not detected in treatments containing SHW.     

Determining biodegradability of plastic materials under controlled and natural composting environments

With the advent of recently promulgated Government regulations on plastics in Mauritius, a study was initiated to examine the biodegradability of two different types of plastic, namely Willow Ridge Plastics - PDQ-H additive (Plastic A) and Ecosafe Plastic - TDPA additive (Plastic B) under controlled and natural composting environments. The results obtained from the controlled composting environment showed that the cumulative carbon dioxide evolution for Plastic A was much higher than that for Plastic B. Plastic A therefore showed a higher level of biodegradation in terms of CO2 evolution than Plastic B. However, from the regression analysis, it was found that the level of CO2 varying with time fitted the sigmoid type curves with very high correlation coefficients (R2 values: 0.9928, 0.9921 and 0.9816, for reference material, inoculum and Plastic A, respectively). The corresponding F-values obtained from the ANOVA analysis together with significance levels of p<0.05 indicated that the three treatments analysed in the biodegradability experiment were significant. The other experiment was undertaken to observe any physical change of Plastics A and B as compared to a reference plastic, namely, compostable plastic bag (Mater-Bi product-Plastic C), when exposed to a natural composting environment. Thermophilic temperatures were obtained for about 3-5 days of composting and the moisture content was in the range of 60-80% throughout the degradation process. It was observed that after 55 days of composting, Plastic C degraded completely while Plastic A and Plastic B did not undergo any significant degradation. It can be concluded that naturally based plastic made of starch would degrade completely in a time frame of 60 days, whereas plastics with biodegradable additive would require a longer time.     

Vanadium recovery from oil fly ash by leaching, precipitation and solvent extraction processes

In order to reduce the environmental impact due to land disposal of oil fly ash from power plants and to valorize this waste material, the removal of vanadium was investigated using leaching processes (acidic and alkaline treatments), followed by a second step of metal recovery from leachates involving either solvent extraction or selective precipitation. Despite a lower leaching efficiency (compared to sulfuric acid), sodium hydroxide was selected for vanadium leaching since it is more selective for vanadium (versus other transition metals). Precipitation was preferred to solvent extraction for the second step in the treatment since: (a) it is more selective; enabling complete recovery of vanadate from the leachate in the form of pure ammonium vanadate; and (b) stripping of the loaded organic phase (in the solvent extraction process) was not efficient. Precipitation was performed in a two-step procedure: (a) aluminum was first precipitated at pH 8; (b) then ammonium chloride was added at pH 5 to bring about vanadium precipitation.     

Passive drainage and biofiltration of landfill gas: Australian field trial

In Australia a significant number of landfill waste disposal sites do not incorporate measures for the collection and treatment of landfill gas. This includes many old/former landfill sites, rural landfill sites, non-putrescible solid waste and inert waste landfill sites, where landfill gas generation is low and it is not commercially viable to extract and beneficially utilize the landfill gas. Previous research has demonstrated that biofiltration has the potential to degrade methane in landfill gas, however, the microbial processes can be affected by many local conditions and factors including moisture content, temperature, nutrient supply, including the availability of oxygen and methane, and the movement of gas (oxygen and methane) to/from the micro-organisms. A field scale trial is being undertaken at a landfill site in Sydney, Australia, to investigate passive drainage and biofiltration of landfill gas as a means of managing landfill gas emissions at low to moderate gas generation landfill sites. The design and construction of the trial is described and the experimental results will provide in-depth knowledge on the application of passive gas drainage and landfill gas biofiltration under Sydney (Australian) conditions, including the performance of recycled materials for the management of landfill gas emissions.     

Valorization of post-consumer waste plastic in cementitious concrete composites

The sheer amount of disposable bottles being produced nowadays makes it imperative to identify alternative procedures for recycling them since they are non-biodegradable. This paper describes an innovative use of consumed plastic bottle waste as sand-substitution aggregate within composite materials for building application. Particularly, bottles made of polyethylene terephthalate (PET) have been used as partial and complete substitutes for sand in concrete composites. Various volume fractions of sand varying from 2% to 100% were substituted by the same volume of granulated plastic, and various sizes of PET aggregates were used. The bulk density and mechanical characteristics of the composites produced were evaluated. To study the relationship between mechanical properties and composite microstructure, scanning electron microscopy technique was employed. The results presented show that substituting sand at a level below 50% by volume with granulated PET, whose upper granular limit equals 5mm, affects neither the compressive strength nor the flexural strength of composites. This study demonstrates that plastic bottles shredded into small PET particles may be used successfully as sand-substitution aggregates in cementitious concrete composites. These new composites would appear to offer an attractive low-cost material with consistent properties; moreover, they would help in resolving some of the solid waste problems created by plastics production and in saving energy.     

Swine manure composting by means of experimental turning equipment

The purpose of research was to test the effectiveness of a prototype of a turning machine and to evaluate the feasability of a farm-scale composting process of the solid fraction of swine manure. A qualitative evaluation of the process and final product was made by monitoring the following parameters: process temperature, oxygen concentration inside the biomass, gaseous emissions (CH4, CO2, NH3, N2O), respiration index, humification index, total and volatile solids, carbon and nitrogen, pH and microbial load. The prototype proved to be very effective from a technical-operational point of view. The composting process exhibited a typical time-history, characterised by a thermophilic phase followed by a curing phase [Chiumenti, A., Chiumenti, R., Diaz, L.F., Savage, G.M., Eggerth, L.L., Goldstein, N., 2005. Modern Composting Technologies. BioCycle-JG Press, Emmaus, PA, USA]. Gas emissions from compost the windrow were more intense during the active phase of the process and showed a decreasing trend from the thermophilic to the curing phase. The final compost was characterized by good qualitative characteristics, a significant level of humification [Rossi, L., Piccinini, S., 1999. La qualità agronomica dei compost derivanti da liquami suinicoli. (Agronomic quality of swine manure compost). L'informatore Agrario 38, 29-31] and no odor emissions. This method of managing manure represents an effective, low cost approach that could be an interesting opportunity for swine farms.