Remediation of Persistent Organic Pollutants Using a Novel Two-Phase Soil Washing Biosorption Process

A two-phase soil washing biosorption process was developed for the remediation of p,p-DDT-contaminated soil. The process involved desorption of contaminants from soil using dilute primary alcohols (40% 1-propanol) followed by contaminant removal from cosolvent solutions using fungal biosorption. Bench scale remediation studies were preformed to simulate ex situ (recycling experiment) or in situ (soil column study) treatment strategies. Both systems were effective at cleaning the soil to below Australian regulatory p,p-DDT levels. After 50–80 hours of soil washing, over 93% of p,p-DDT was removed from the soil(990 mg kg^-1 to <65 mg kg^-1) using either of these methods.p,p-DDT was removed from the cosolvent phase by sorption onto the fungal biomass. This resulted in only low levels of p,p-DDT remaining in the cosolvent solution(<1.5 mg l^-1). The application of both treatment strategies resulted in the rapid clean up of p,p-DDT-contaminated soil and the potential to recycle cosolvent solutions. The ability to recycle cosolvent solutions provides a mechanism for cost reductions of the remediation strategy.     

A rapid and sensitive analytical method for the quantification of residues of endosulfan in blood

A new sensitive analytical procedure has been developed for the determination of residues of endosulfan in human blood samples. The method involves the extraction of residues of endosulfan from blood samples by the addition of 60% sulfuric acid at 10 degrees C, liquid/liquid partitioning by using hexane and acetone mixture (9:1) and quantification by using GC-ECD. Residues of endosulfan in blood samples were quantified as the sum of alpha-endosulfan, beta-endosulfan, endosulfan sulfate and endosulfandiol. The influence of temperature during the extraction has been studied. Recovery experiments were conducted over the concentration range 1.0-50 ng ml(-1) and the relative standard deviation calculated. The method was found to be sufficiently sensitive to quantify the residue of total endosulfan up to the 1.0 ng ml(-1) level. The recovery was 92% with a calculated relative standard deviation of 1.96%. Conversion of endosulfan to endosulfandiol is found to be less than 0.5% under the defined conditions. The method was applied to the analysis of residue contents of endosulfan and its metabolites in blood samples collected from the exposed population. The data obtained has been confirmed by GC-MS-EI in selective ion monitoring (SIM) mode.     

Treatment of Arctic wastewater by chemical coagulation,UV and peracetic acid disinfection

Conventional wastewater treatment is challenging in the Arctic region due to the cold climate and scattered population. Thus, no wastewater treatment plant exists in Greenland, and raw wastewater is discharged directly to nearby waterbodies without treatment. We investigated the efficiency of physicochemical wastewater treatment, in Kangerlussuaq, Greenland. Raw wastewater from Kangerlussuaq was treated by chemical coagulation and UV disinfection. By applying 7.5 mg Al/L polyaluminium chloride (PAX XL100), 73% of turbidity and 28% phosphate was removed from raw wastewater. E. coli and Enterococcus were removed by 4 and 2.5 log, respectively, when UV irradiation of 0.70 kWh/m³ was applied to coagulated wastewater. Furthermore, coagulated raw wastewater in Denmark, which has a chemical quality similar to Greenlandic wastewater, was disinfected by peracetic acid or UV irradiation. Removal of heterotrophic bacteria by applying 6 and 12 mg/L peracetic acid was 2.8 and 3.1 log, respectively. Similarly, removal of heterotrophic bacteria by applying 0.21 and 2.10 kWh/m³ for UV irradiation was 2.1 and greater than 4 log, respectively. Physicochemical treatment of raw wastewater followed by UV irradiation and/or peracetic acid disinfection showed the potential for treatment of arctic wastewater.     

Integration of traditional and innovative characterization techniques for flux-based assessment of Dense Non-aqueous Phase Liquid (DNAPL) sites

Key attributes of the source zone and the expanding dissolved plume at a trichloroethene (TCE) site in Australia were evaluated using trends in groundwater monitoring data along with data from on-line volatile organic compound (VOC) samplers and passive flux meters (PFMs) deployed in selected wells. These data indicate that: (1) residual TCE source mass in the saturated zone, estimated using two innovative techniques, is small ( 10 kg), which is also reflected in small source mass discharge ( 3 g/day); (2) the plume is disconnecting, based on TCE concentration contours and TCE fluxes in wells along a longitudinal transect; (3) there is minimal biodegradation, based on TCE mass discharge of  6 g/day at a plume control plane  175 m from source, which is also consistent with aerobic geochemical conditions observed in the plume; and (4) residual TCE in the vadose zone provides episodic inputs of TCE mass to the plume during infiltration/recharge events. TCE flux data also suggest that the small residual TCE source mass is present in the low-permeability zones, thus making source treatment difficult. Our analysis, based on a synthesis of the archived data and new data, suggests that source treatment is unwarranted, and that containment of the large TCE plume ( 1.2 km long,  0.3 km wide; 17 m deep;  2000–2500 kg TCE mass) or institutional controls, along with a long-term flux monitoring program, might be necessary. The flux-based site management approach outlined in this paper provides a novel way of looking beyond the complexities of groundwater contamination in heterogeneous domains, to make intelligent and informed site decisions based on strategic measurement of the appropriate metrics.     

Toxicity of fenamiphos and its metabolites to the cladoceran Daphnia carinata: the influence of microbial degradation in natural waters

The acute toxicity of an organophosphorous pesticide, fenamiphos and its metabolites, fenamiphos sulfoxide, fenamiphos sulfone, fenamiphos phenol, fenamiphos sulfoxide phenol and fenamiphos sulfone phenol, to a cladoceran, Daphnia carinata was studied in both cladoceran culture medium and natural water collected from a local river. The toxicity followed the order: fenamiphos>fenamiphos sulfone>fenamiphos sulfoxide. The hydrolysis products of fenamiphos, F. sulfoxide (FSO) and F. sulfone (FSO(2)) (F. phenol, FSO phenol and FSO(2) phenol) were not toxic to D. carinata up to 500microgl(-1) water, suggesting hydrolysis reaction leads to detoxification. Also the toxicity was reduced in natural water compared to the cladoceran culture medium due to microbial mediated degradation of toxicants in the natural water. Fenamiphos and its metabolites were stable in both cladoceran water and filter-sterilised natural water while these compounds showed degradation in unfiltered natural water implicating the microbial role in degradation of these compounds. To our knowledge this is the first study on acute toxicity of fenamiphos metabolites to cladoceran and this study suggests that the organophosphate pesticides are highly toxic to fresh water invertebrates and therefore pollution with these compounds may adversely affect the natural ecosystems.     

Efficacy of biochar in removal of organic pesticide,Bentazone from watershed systems

Abstract

Bentazone is one of the toxic insecticides used to control forest tent caterpillar moths, boll weevils, gypsy moths, and other types of moths in various field crops. We report the efficacy of biochar prepared from the Azardirachta Indica waste biomass as adsorbent for removal of Bentazone. Biochar material was prepared by pyrolysis process under limited oxygen conditions. Biochar material was characterized by proximate and ultimate analysis, SEM analysis, FTIR analysis and TG/DTA analyses. The Bentazone adsorption capacity by biochar from aqueous solutions was assessed. Effect of time, adsorbent dosage, insecticide concentration and pH on the adsorption characteristics of the biochar were evaluated. Adsorption parameters were obtained at equilibrium contact time of 150?min, with biochar dosage of 0.5?g at pH 8. From the optimization studies, desirability of 0.952 was obtained with response (adsorption uptake) of 79.40?mg/g, for initial concentration of insecticide (50?mg/L), adsorbent dosage (0.448?g), time 30.0?min and pH 2. The adsorption isotherm data for the removal of Bentazone fitted well with the Freundlich isotherm. This study indicates that the biochar produced from the bark of Azardirachta Indica biomass could be employed as a potential adsorbent for removal of synthetic organic pollutants from the water streams.     

Simultaneous control of Hg0, SO2, and NOx by novel oxidized calcium-based sorbents

Efforts to develop multipollutant control strategies have demonstrated that adding certain oxidants to different classes of Ca-based sorbents leads to a significant improvement in elemental Hg vapor (Hg0), SO2, and NOx removal from simulated flue gases. In the study presented here, two classes of Ca-based sorbents (hydrated limes and silicate compounds) were investigated. A number of oxidizing additives at different concentrations were used in the Ca-based sorbent production process. The Hg0, SO2, and NOx capture capacities of these oxidant-enriched sorbents were evaluated and compared to those of a commercially available activated carbon in bench-scale, fixed-bed, and fluid-bed systems. Calcium-based sorbents prepared with two oxidants, designated C and M, exhibited Hg0 sorption capacities (approximately 100 microg/g) comparable to that of the activated carbon; they showed far superior SO2 and NOx sorption capacities. Preliminary cost estimates for the process utilizing these novel sorbents indicate potential for substantial lowering of control costs, as compared with other processes currently used or considered for control of Hg0, SO2, and NOx emissions from coal-fired boilers. The implications of these findings toward development of multipollutant control technologies and planned pilot and field evaluations of more promising multipollutant sorbents are summarily discussed.     

Chemistry of inorganic arsenic in soils: II. Effect of phosphorus, sodium, and calcium on arsenic sorption

There are more than 10000 arsenic (As) contaminated sites in Australia. The ability of soils at these contaminated sites to sorb As is highly variable and appreciable amounts of As have been recorded in the subsurface soils. The potential risk of surface and ground water contamination by As at these sites is a major environmental concern. Factors that influence adsorption capacity of soils influence the bioavailability and subsequent mobility of As in soils. In the present study we investigated the effect of PO4(3-) and Na+ and Ca2+ on the sorption of AsV and AsIII by an Oxisol, a Vertisol, and two Alfisols. The presence of P (0.16 mmol L(-1)) greatly decreased AsV sorption by soils containing low amounts of Fe oxides (<100 mmol kg(-1)), indicating competitive adsorption between P and AsV for sorption sites. In contrast, the presence of a similar amount of P had little effect on the amount of AsV adsorbed by soils with high Fe content (>800 mmol kg(-1)). However, AsV sorption substantially decreased from 0.63 to 0.37 mmol kg(-1) as P concentration was increased from 0.16 to 3.2 mmol L(-1) in selected soils. This suggests increased competition between P and AsV for soil sorption sites, through either the higher affinity or the effect of mass action of the increasing concentration of P in solution. A similar effect of P on AsIII sorption was observed in the low sorbing Alfisol and high affinity Oxisol. However, the amount of AsIII sorbed by the Oxisol was much greater than the Alfisol for all treatments. The presence of Ca2+ increased the amount of AsV sorbed compared with that of Na+ and was manifested through changes in the surface charge characteristics of the soils. A similar trend in AsIII sorption was recorded with changes in index cation, although the effect was not as marked as recorded for AsV.     

Effect of isopod parasite, Cymothoa indica on gobiid fish, Oxyurichthys microlepis from Parangipettai coastal waters (South-east coast of India)

The present study reported for the first time on the effect of isopod parasite, Cymothoa indica infestation on Oxyurichthys microlepis an ecologically important gobiid fish from Parangipettai coastal environment (South-east coast of India). The loss of weight in host fishes (male 20.47 and female 32.84%) were observed due to parasitism. The weight of uninfested female fish was found to be higher than that of infested one. The calus like thickening developed on the gill arch and gill filaments of host fish due to the persistent irritation caused by the appendages of the parasite. The reduction of gill surface area was observed due to the attachment of the parasites. The maximum reduction noticed in the first gill arch is mainly due to the heavy pressure exerted by the parasite. Details of gross lesions observed in the branchial chamber, buccal cavity and body surface was enumerated. Heavy infestations of parasitic juveniles have the potential to kill small fingerlings. The swimming capacity of the fish was also found to be affected.     

Maize straw and rice husk-derived biochars produced in a simple metal kiln: characteristics and effects on crop productivity in three fields

Journal of Material Cycles and Waste Management - Maize straw- and rice husk-derived biochars were produced in a simple metal kiln without automated control. Their characteristics and effects on...