Membrane bioreactor technology: A novel approach to the treatment of compost leachate

Compost leachate forms during the composting process of organic material. It is rich in oxidizable organics, ammonia and metals, which pose a risk to the environment if released without proper treatment. An innovative method based on the membrane bioreactor (MBR) technology was developed to treat compost leachate over 39 days. Water quality parameters, such as pH, dissolved oxygen, ammonia, nitrate, nitrite and chemical oxygen demand (COD) were measured daily. Concentrations of caffeine and metals were measured over the course of the experiment using gas chromatography – mass spectrometry (GC/MS) and inductively coupled plasma – mass spectrometry (ICP–MS) respectively. A decrease of more than 99% was achieved for a COD of 116 g/L in the initial leachate. Ammonia was decreased from 2720 mg/L to 0.046 mg/L, while the nitrate concentration in the effluent rose to 710 mg/L. The bacteria in the MBR system adjusted to the presence of the leachate, and increased 4 orders of magnitude. Heavy metals were removed by at least 82.7% except copper. These successful results demonstrated the membrane bioreactor technology is feasible, efficient method for the treatment of compost leachate.     

Matrix Diffusion Modeling Applied to Long‐Term Pump‐and‐Treat Data: 1. Method Development

Despite the installation in the 1980s and 1990s of hydraulic containment systems around known source zones (four slurry walls and ten pump‐and‐treat systems), trichloroethene (TCE) plumes persist in the three uppermost groundwater‐bearing units at the Middlefield‐Ellis‐Whisman (MEW) Superfund Study Area in Mountain View, California. In analyzing TCE data from 15 recovery wells, the observed TCE mass discharge decreased less than an order of magnitude over a 10‐year period despite the removal of an average of 11 pore volumes of affected groundwater. Two groundwater models were applied to long‐term groundwater pump‐and‐treat data from 15 recovery wells to determine if matrix diffusion could explain the long‐term persistence of a TCE plume. The first model assumed that TCE concentrations in the plume are controlled only by advection, dispersion, and retardation (ADR model). The second model used a one‐dimensional diffusion equation in contact with two low‐permeability zones (i.e., upper and lower aquitard) to estimate the potential effects of matrix diffusion of TCE into and out of low‐permeability media in the plume. In all 15 wells, the matrix diffusion model fit the data much better than the ADR model (normalized root mean square error of 0.17 vs. 0.29; r² of 0.99 vs. 0.19), indicating that matrix diffusion is a likely contributing factor to the persistence of the TCE plume in the non‐source‐capture zones of the MEW Study Area's groundwater‐extraction wells. © 2013 Wiley Periodicals, Inc.     

Behaviour and dynamics of di-ammonium phosphate in bauxite processing residue sand in Western Australia—I. NH<Subscript>3</Subscript> volatilisation and residual nitrogen availability

Background, aim and scope

Australia is the largest producer of bauxite in the world, with an annual output of approximately 62 million metric dry tons in 2007. For every tonne of alumina, about 2 tonnes of highly alkaline and highly saline bauxite-processing residue are produced. In Western Australia, Alcoa World Alumina, Australia (Alcoa) produces approximately 15 MT of residue annually from its refineries (Kwinana, Pinjarra and Wagerup). The bauxite-processing residue sand (BRS) fraction represents the primary material for rehabilitating Alcoa’s residue disposal areas (RDAs). However, the inherently hostile characteristics (high alkalinity, high salinity and poor nutrient availability) of BRS pose severe limitations for establishing sustainable plant cover systems. Alcoa currently applies 2.7 t ha^?1 of di-ammonium phosphate ((NH₄)₂HPO₄; DAP)-based fertiliser as a part of rehabilitation of the outer residue sand embankments of its RDAs. Limited information on the behaviour of the dominant components of this inorganic fertiliser in highly alkaline BRS is currently available, despite the known effects of pH on ammonium (NH₄) and phosphorus (P) behaviour. The aim of this study was to quantify the effects of pH on NH₃ volatilisation and residual nitrogen (N) in BRS following DAP applications.

Methods

The sponge-trapping and KCl-extraction method was used for determining NH₃ volatilisation from surface-applied DAP in samples of BRS collected from each of Alcoa’s three Western Australia Refineries (Kwinana, Pinjarra, Wagerup) under various pH conditions (pH 4, 7, 9 and 11). Following cessation of volatilisation, the residual N was extracted from BRS using 2 M KCl and concentrations of NH ₄ ⁺ –N and NO ₃ ^? –N were determined by flow injection analysis.

Results

The quantities of NH₃ volatilised increased dramatically as the pH increased from 4 to 11. Much of the N lost as NH₃ (up to 95.2%) occurred within a short period (24 h to 7 days), particularly for the pH 9 and 11 treatments. Concentrations of residual NH ₄ ⁺ –N recovered in DAP-treated BRS at the end of the experiment decreased with increasing pH. This finding was consistent with increasing loss of N via volatilisation as pH increased. The concentration of NO ₃ ^? –N was very low due to no nitrification in BRS.

Discussion

The pH was a key driver for NH₃ volatilisation from DAP-treated BRS and primarily controlled N dynamics in BRS. Results indicate that NH₄ not adsorbed by BRS was highly susceptible to volatilisation. The likely lack of nitrifying bacteria did not allow conversion of ammonium to nitrate, thereby further exacerbating the potential for loss via volatilisation

Conclusions

It was demonstrated that the pH is the key factor controlling the loss of inorganic N from BRS. Although volatilisation was considerably lower at pH 4, achieving this pH reduction in the field is not possible at present. Findings from this study highlight the need to better understand which forms of N fertiliser are most suitable for use in highly alkaline BRS.

Recommendation and perspectives

Although pH reduction is the most likely means of stopping NH₃ volatilisation in BRS, it is economically and operationally unfeasible to add sufficient acidity for adequately lowering pH in the BRS for revegetation. More attention on forms of fertilisers more suitable to highly alkaline, microbially inert soil conditions appears to be warranted.

     

Processing of whey from dairy industry waste

An investigation carried out in 11 dairies in Serbia has shows that 78.75 % of whey, a by-product of cheese industry, is emitted into river systems, thus contributing to the organic pollution of the environment. This pollution can be avoided by processing of whey into food and pharmaceuticals. It is shown that low-temperature regime of whey concentration and fractionation, based on vacuum concentration and diafiltration, preserves whey proteins undenaturated, as proved by differential scanning calorimetry method. Functional native whey proteins based food products, with potentially high immunomodulatory activity, are obtained.     

Selective separation of deltamethrin by molecularly imprinted polymers using a β-cyclodextrin derivative as the functional monomer

A deltamethrin-imprinted polymer (MIP₁) was prepared using bis(-6-O-butanediacid monoester)-β-cyclodextrin (BBA-β-CD) as the functional monomer and toluene 2,4-diisocyanate (TDI) as the cross-linker. In comparison to the molecularly imprinted polymer where β-CD was applied as the functional monomer (MIP₂), MIP₁ showed a higher specific binding capacity (ΔC_P) and an improved imprinting factor (IF) for deltamethrin. The selective recognition experiments demonstrated that compared to MIP₂, MIP₁ could better recognize its template over other substrates that had similar chemical structures. The solid phase extraction (SPE) of deltamethrin using MIP₁ as the adsorbent was further investigated. The recoveries of the molecularly imprinted solid phase extraction (MISPE) column for deltamethrin were 83.2–93.4% with relative standard deviations (RSD) of 2.03–6.19%. The method has been successfully applied to the enrichment of trace deltamethrin from real water samples.     

Heavy metals in brick kiln located area using atomic absorption spectrophotometer: a case study from the city of Peshawar, Pakistan

Environmental pollution is one of the burning issues of the world. In developed countries, there are lot of awareness about the environment and the impact of various industries on their life and surroundings. A little has been done in this direction in developing countries. In Pakistan, a big problem is the rapid conglomeration of the brick kilns in the outskirts of nearly all the urban centers to cope with the rapid construction work in big cities. A huge amount of low-grade coal or rubber tires is used as fuel in a very non-scientific manner. The purpose of the present study was to look into the impact of the brick kilns on the different aspects of environmental pollution caused by these kilns. Concentration of metals Cu, Co, Zn, Pb, Cr, Ni, Cd, and Mn were measured on 36 soil samples collected from the area and the same number of plant samples in order to establish the distribution of heavy metals in the area and to determine the effect of this distribution on the surrounding atmosphere and the possible effects on human life.     

Deep bed filtration of anaerobic cattle manure effluents with natural zeolite

Abstract

This study was carried out in a pilot plant for the treatment of anaerobic cattle manure waste. The pilot plant consisted of a semicontinous anaerobic reactor, a settling tank, a filtration process and an ionic exchange column. The study was focused on the filtration process, with natural zeolite as filtering material. In the filtration process different media sizes of natural zeolites packed in columns were tested. The ranges of media size were 0.4 ‐ 1.0, 1.0 ‐ 3.0 and 3.0 ‐ 5.0 mm. Filtration systems operated by gravity flow from 2 to 10 m³m^‐2h^‐1. The process control was done by assays of solids, turbidity, total and soluble COD, ammonium and orthophosphate. The results showed a better behaviour in the filters packed with a media size range between 1.0 and 3.0 mm, operating at 7 m³m^‐2h^‐1, principally when effluent gross particles were previously retained in an Heterogeneous Media Filter, operating at 4 m³m^‐2h^‐1. The head losses diagrams in the filter runs were obtained, at each operational conditions. The hydraulic behaviour of traditional silica sand and natural zeolite beds were compared at the same operational conditions.     

Monitoring trace elements generated by automobiles: air pollutants with possible health impacts

Major transformations in the environmental composition are principally attributable to the combustion of fuels by automobiles. Motorized gasoline-powered two-stroke auto-rickshaws (TSA) and compressed natural gas (CNG)-powered four-stroke auto-rickshaws (FSA) are potential source of air pollution in south Asia and produce toxic amount of particulate matter (PM) to the environment. In this study, we attempted to characterize elemental pollutants from the PM of TSA and FSA using proton-induced X-ray emission (PIXE) analysis. The observations of the existing investigation recognized significant increase in Al (P?<?0.05), P (P?<?0.01), and Zn (P?<?0.01) from the PM samples of FSA. In addition, the concentrations of Cu, Fe, K, Mg, Na and S were also observed exceeding the recommended National Institute for Environmental Studies limits. On the contrary, increased concentration of Sr and V were observed in the PM samples from TSA. It is generally believed that FSA generates smaller amount of PM but data obtained from FSA are clearly describing that emissions from FSA comprised potentially more toxic substances than TSA. The current research is specific to metropolitan population and has evidently revealed an inconsistent burden of exposure to air pollutants engendered by FSA in urban communities, which could lead to the disruption of several biological activities and may cause severe damage to entire ecological system.     

Carbendazim dissipation in the biomixture of on-farm biopurification systems and its effect on microbial communities

The impact of repeated carbendazim (CARB) applications on the extent of CARB dissipation, the microbial diversity, the community level physiological profile (CLPP), and the enzymatic activity within the biomixture of an on-farm biopurification system was evaluated. After three successive CARB applications, the CARB dissipation efficiency was high; the efficiency of dissipation was 87%, 94% and 96% after each application, respectively. Although microbial enzymatic activity was affected significantly by CARB application, it could recover after each CARB pulse. Likewise, the numbers of cultivable bacteria, fungi and actinomycetes (as measured in CFUs) were slightly affected by the addition of CARB, but the inhibitory effect of the pesticide application was temporary. Denaturing gradient gel electrophoresis (DGGE) and Biolog Ecoplate assays demonstrated that the microbial populations remained relatively stable over time when compared to the control. The results obtained herein therefore demonstrate the high dissipation capacity of this biomixture and highlight the microbiological robustness of this biological system.