Journal of Hazardous, Toxic, and Radioactive Waste

The capacity of white rot fungus, Pleurotus ostreatus, to biodegrade naphthalene present in sandy-clay-loam soil samples at concentrations of 50, 100, 200, and $500\mathrm{mg}/\mathrm{L}$ was investigated experimentally. Using high-pressure liquid chromatography (HPLC), triplicate samples of liquid extracts from both fungus-inoculated and control (noninoculated) soil samples were taken at time periods of 0, 30, 60, and 90 days for determination of residual naphthalene concentrations. Relevant factors (naphthalene concentration, treatment duration, and residual naphthalene concentration) and their interaction were compared for both inoculated and control samples, using pair plots and level of significance. Overall, samples inoculated with P. ostreatus had reduced naphthalene concentrations to 1–40% of initial concentrations for the 90-day sampling period, compared with 63–82% for control treatments. In the control soil samples, extractable naphthalene increased by approximately 2–5% of initial content between 60 and 90 days. In conclusion, the results show that Pleurotus ostreatus can be used as an effective bioremediation agent for naphthalene-contaminated soils.

This study is aimed at a performance evaluation of downflow hanging sponge (DHS) systems using mixed fungal and bacterial cultures for posttreatment of upflow anaerobic sludge blanket (UASB) effluents of tapioca starch wastewater. The effects of sludge composition on the microbial activity and effluent organic matter were also investigated. The whole experiment consisted of RUN I and RUN II with hydraulic retention times (HRTs) of 7 and 1 h, respectively, and the organic loading rates (OLR) ranged from 2.0 to $6.0\mathrm{kg}\mathrm{COD}/{\mathrm{m}}^3\mathrm{da}{\mathrm{y}}^{-1}$ . The organic removal efficiencies were higher in RUN II, in the 94–96% range for both DHS systems. Under steady-state conditions, the volatile suspended solids (VSS) concentration in the sludge retained in the fungal downflow hanging sponge (FDHS) system showed little change, indicating a balance between the degradation of old biomass and the accumulation of the fresh biomass. Also, there was no significant removal of nitrogen in the FDHS system. However, the nitrogen was reduced in the bacterial downflow hanging sponge (BDHS) system, possibly through nitrification and denitrification processes. Both DHS systems exhibited marked stability with regard to the fluctuations in hydraulic loading. The results of this study showed that the proposed DHS systems could be promising for posttreatment of UASB effluents.

Diesel fuel and diesel exhaust are known to be highly mutagenic partly because of the presence of polyaromatic hydrocarbons (PAHs) and their derivatives. The present study investigated the PAHs content in the diesel fuel fed to a diesel generator and also in the gas and particulate phase of generator emissions. Mutagenicity of the exhaust was also determined. Exhaust emissions were collected by a stack sampler: gas phase on XAD-2 resin while particulate phase on glass fibre thimble. PAHs were characterized by a gas chromatograph by using a flame ionization detector. The low molecular weight PAHs dominated in the fuel, whereas the high molecular weight PAHs dominated in the exhaust with a greater emission factor in the particulate phase. The results reveal the pyrosynthesis of high molecular weight PAHs during the combustion process. Emissions also increased with increase in load. Extract of exhaust emissions were positive in both Salmonella typhimurium tester strains TA 98 and TA 100 without metabolic activation, suggesting the presence of direct mutagens that can cause both frame-shift and base-pair mutation. The mutagenic response was greater for TA 100 than TA 98, suggesting greater activity for base-pair mutagenicity than frame-shift mutagenicity. Mutagenic activity increased with the increase in load.

Solid waste management (SWM) is one of the priority issues concerning the protection of the environment and conservation of natural resources. It is imperative for environmental managers and planners to follow a sustainable approach to municipal solid waste (MSW) management and to integrate strategies that will produce the best practicable option. Solid waste management is among the basic essential services provided by municipal authorities in the country to keep urban areas clean. The methodology presented in this work is based on optimization formulation in which the overall objective is the minimization of daily waste-management costs and their components. The cost includes the investment, waste handling expenses, transportation costs, expenses owing to the use of replacement trucks, and the income from waste products, such as refuse-derived fuel (RDF) and energy. The constraints include those linking waste flow among sources, plants and landfills, capacity, site selection, facility availability, environmental, and landfill saturation. The integer and mixed-integer mathematical formulation of the solid waste optimization model was solved by using commercially available optimization software, Lingo 10.0. Different scenarios were constituted to demonstrate the potential applicability of the model. The sensitivity analysis indicated that the total cost lowered with the high quality of incinerators (with lesser unrecovered wastes). Sensitivity analysis of different landfill sites reveals their suitability for different planning horizons. The mixed-integer optimization model consistently performed better than the integer model.

A new method, called modified Gompertz model, was proposed to interpret solid state decomposition. To verify the validity of this new model, the thermal degradation of polypropylene (PP) was performed and the results of curves fitting of thermogravimetry (TG) and derivative thermogravimetrical (DTG) from the Gompertz model were compared with those obtained from the traditional general model. The Arrhenius kinetic parameters used in the general model were derived from three traditional methods (i.e., Friedman, Freeman-Carroll, and Ozawa methods). For the Arrhenius parameters calculation, the heating temperature range was set from 298 to 1073 K and three different heating rates of 5, 10, and $15\mathrm{K}/\min$ were selected. The sum of square errors (SSE) and the coefficient of determination ( $r^2$ ) were calculated for all simulated data obtained from the modified Gompertz model and the general model. Statistical results show that all SSE values obtained from the modified Gompertz model are much smaller than those from the general model, and every $r^2$ value of conversion of modified Gompertz model is greater than 0.987. The writers found that the TG and DTG curves simulated by the modified Gompertz model have a better fit to the experimental data than those curves reproduced from the general model with values of Arrhenius parameters obtained from the traditional techniques. These results suggested that the modified Gompertz model can be considered as a simple way to describe the thermal decomposition reaction behavior.

Toxicity tests are important for assessing the effects of complex chemical mixtures, such as waste drilling mud, on aquatic ecosystems. When waste drilling mud is released into the marine environment, strong ocean currents perhaps separate the drilling mud into a solid phase (SP) and a suspended particulate phase (SPP). A comprehensive assessment of drilling mud and base oil was carried out in the laboratory for acute fish toxicity (freshwater fish, marine fish, and benthic organisms) and biodegradability. The results presented in this paper indicate that the ${\mathrm{LC}}_{50}$ 96 h for fresh water, marine and benthic organisms was in the order of base oil $>\mathrm{SP}>\mathrm{SSP}$ . The 28-day biodegradability of base oil was also more than that of drilling mud. The results also showed that nonaqueous drilling fluids (NADFs) are readily biodegradable. The Spearmen results clearly showed the effects on fish populations from the discharge of drilling mud into aquatic systems. The results showed that the use of NADFs instead of water-based fluids (WBFs) would have lesser adverse impact on the environment.

This work discusses the oxidation of ammonia ( ${\mathrm{NH}}_3$ ) at temperatures between 150 and 400°C (423 and 673 K) by selective catalytic oxidation (SCO) over a nanoarchitectures $\mathrm{CuO}/{\mathrm{CeO}}_2$ composite catalyst that was prepared through coprecipitation (CP) method of copper nitrate and cerium nitrate at molar ratio of $7:3$ . The catalysts were characterized using thermogravimetric analysis (TGA), BET, analytical scanning transmission electron microscopy (AEM), and cyclic voltammetric (CV) measurement. The experimental results demonstrate that the presence of ammonia was removed around 97% ${\mathrm{NH}}_3$ reduction was achieved during catalytic oxidation over the nanoarchitectures $\mathrm{CuO}/{\mathrm{CeO}}_2$ composite catalyst calcine treated at 500°C (773 K) with an oxygen content of 4%. The composite particles were characterized by AEM, with a particle size around nanoscale particle sizes ( $\sim 5\mathrm{nm}$ ) with high dispersion phenomena. The nanoarchitectures $\mathrm{CuO}/{\mathrm{CeO}}_2$ composite-induced cytotoxicity in the human lung cell line, MRC-5, was tested, and cell survival was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetra-zolium (MTS) analysis in vitro. These results indicated that the nanoarchitectures $\mathrm{CuO}/{\mathrm{CeO}}_2$ composite catalyst is only weakly cytotoxic to human lung cells.

This paper reports on the comparison of Fenton-like and electrochemical-assisted Fenton processes on 2,6-dimethylaniline removal. The influences of initial pH, ferric ion, hydrogen peroxide, and electric current on the oxidation of 2,6-dimethylaniline were also evaluated to determine the optimum operating parameters. Results showed that oxidation efficiency of the electro-Fenton process was better than the Fenton process. The experimental data revealed that increasing ferric ions, hydrogen peroxide concentration, and applied electric current enhanced the oxidation efficiency. However, too much ferric ion and hydrogen peroxide decreased the removal efficiency because of the scavenging effects that occur in the solution. When the electric current was increased to 5 A, the regeneration of ferrous ions decreased. This was because a too-high electric current resulted in water electrolysis and reduced the current efficiency of ferric reduction and therefore increased power cost. The results also showed that low pH is preferred for 2,6-dimethylaniline degradation, and increasing the initial pH from 1.5 to 2.0 increased the regeneration of ferrous ion. However, when the initial pH was increased to 3.0, the ferrous ion easily reacted with hydroxide and then generated iron oxide, leading to a decrease in the ferrous concentration. In addition, the experiments also revealed that the greatest 2,6-dimethylaniline removal was achieved when 1 mM of ferric ion, 20 mM of hydrogen peroxide, and a current of 1 A at pH 2 were applied. Consequently, the electro-Fenton process is a viable alternative in the degradation of 2,6-dimethylaniline.

Remediation of sites contaminated by toxic chlorinated organic compounds by using nanoscale iron particles (NIP) has received great attention owing to their high reactivity resulting from small size and large reactive surface area. However, adequate delivery of NIP into the contaminated zones for in situ remediation applications is difficult because of NIP agglomeration and sedimentation. Different surface modifications of NIP are suggested to enhance the transport of NIP in soils. This study investigated the transport and remediation efficiency of bare NIP and lactate-modified NIP (LMNIP) in field sand contaminated with pentachlorophenol (PCP). Soil column experiments were conducted to investigate the reactivity and transport of NIP and LMNIP at different concentrations (1 and $4\mathrm{g}/\mathrm{L}$ ) under two different constant hydraulic gradients, and the consequent degradation of PCP in the soil. Bare NIP was transported only to limited distances and its distribution through the soil was nonuniform; however, LMNIP was transported uniformly throughout the soil column. Surface modification with aluminum lactate retarded agglomeration and sedimentation of NIP, but the reactivity of NIP decreased. Permeability of the soil was not impacted at low concentrations of NIP; however, at higher concentrations, NIP appeared to clog the pores, reducing soil permeability. LMNIP did not clog the pores even at higher concentration and maintained higher flow, indicating no impact on the permeability. The degradation of PCP was 53.2 and 54.8% with bare NIP at concentrations of 1 and $4\mathrm{g}/\mathrm{L}$ , respectively, whereas the degradation of PCP was 61 and 51.6% with LMNIP at concentrations of 1 and $4\mathrm{g}/\mathrm{L}$ , respectively. The removal of PCP from the soil on the basis of effluent analysis ranged from 6 to 14%. The low degradation of PCP may be attributed to varying reactivity depending on the dissociation and desorption of PCP from soil as a function of soil pH changes, as NIP is transported through the soil. Surface coating with lactate in LMNIP also may have hindered the direct contact of PCP with NIP during the initial stages of transport, but the reactivity of LMNIP increases to the same level as bare NIP at later times.

Using mass balance studies, we show that wheat straw readily bound several times its own weight in crude oil floating on salt water, the straw was reusable following repeated extractions of the oil with diesel, and its presence significantly increased the rate of biodegradation of the oil without the use of dispersants. Previous studies in this area have indicated a preference for synthetic polymeric materials because of their ability to bind greater amounts of oil and their reusability, as compared to organic materials including straw. However, it is clear that plastic leads to ecological problems in marine environments and does not typically provide bioavailable nutrients such as nitrogen or phosphorus to aid the natural oil biodegradation process. Our results suggest the advisability of using biomass such as straw for crude oil remediation.

As a case study, the potential to use bottom ash and fly ash from a large-sized (120 MW) bubbling fluidized bed boiler (BFB) at the power plant of a fluting board mill were assessed to determine their suitability for use as an earth construction agent. In addition, the extractability of heavy metals in the ashes was determined using artificial sweat and gastric fluids to assess the potential occupational risk from ash handling. Owing to the relatively high total concentration of polycyclic aromatic hydrocarbons (PAHs) [ $23.0\mathrm{mg}/\mathrm{kg}$ ; dry weight (d.w.)], and the extractable concentrations of Mo ( $3.9\mathrm{mg}/\mathrm{kg}$ ; d.w.) and Se ( $0.2\mathrm{mg}/\mathrm{kg}$ ; d.w.) in the fly ash, which exceed the Finnish limit values for materials used in covered earth construction ( $20\mathrm{mg}/\mathrm{kg}$ ; d.w. for PAHs, $0.5\mathrm{mg}/\mathrm{kg}$ ; d.w. for Mo, and $0.1\mathrm{mg}/\mathrm{kg}$ ; d.w. for Se), the utilization of this ash residue fraction in such structures requires an environmental permit. Because of the high extractability of certain heavy metals in fly ash by using an artificial gastric fluid, e.g., Ba ( $446\mathrm{mg}/\mathrm{kg}$ ; d.w.), V ( $65.6\mathrm{mg}/\mathrm{kg}$ ; d.w.), Zn ( $100\mathrm{mg}/\mathrm{kg}$ ; d.w.), Cu ( $38.3\mathrm{mg}/\mathrm{kg}$ ; d.w.), and As ( $36.7\mathrm{mg}/\mathrm{kg}$ ; d.w.), the careful handling of this ash residue is recommended to prevent the ingestion and penetration of ash particles across the human gastrointestinal tract.

Pharmaceutical residues are increasingly found in wastewater treatment plant effluents and river water in very low concentrations at nanograms per liter levels in many countries. In this study, samples were collected from seven wastewater treatment plants (WWTPs) and downstream surface waters in Bangkok, Thailand during July and October 2009 and January 2010. Solid phase extraction (SPE) followed by high-pressure liquid chromatography-mass spectrometry-mass spectrometry (HPLC/MS/MS) technique were used to detect eight pharmaceuticals including caffeine, acetaminophen, roxithromycin, ciprofloxacin, trimethoprim, lincomycin, enrofloxacin, and erythromycin. Levels of pharmaceutical residues in the influents on average were the highest for caffeine ( $9,052\mathrm{ng}/\mathrm{L}$ ), followed by acetaminophen ( $8,630\mathrm{ng}/\mathrm{L}$ ), and roxithromycin ( $235\mathrm{ng}/\mathrm{L}$ ). The same three pharmaceuticals showed the top three levels in the effluents (caffeine: $797\mathrm{ng}/\mathrm{L}$ , acetaminophen: $92\mathrm{ng}/\mathrm{L}$ , and roxithromycin: $50\mathrm{ng}/\mathrm{L}$ ). The concentration of caffeine was also the highest in downstream surface water samples ( $2,393.4\mathrm{ng}/\mathrm{L}$ ). Acetaminophen ( $839.3\mathrm{ng}/\mathrm{L}$ ) and roxithromycin ( $54.7\mathrm{ng}/\mathrm{L}$ ) were at the second and third highest levels. Caffeine and acetaminophen in WWTP effluents were at very low levels compared with the influent concentrations.