The biochemical response to different Cr and Cd concentrations in soils amended with organic wastes

The effects of adding municipal solid waste (MSW) or poultry manure (PM) on the biochemical properties of a soil polluted with Cr and Cd were studied. Soil was mixed with Cr(NO₃)₃ and Cd(NO₃)₂ to give three concentrations (0, 100, and 250 mg Cr kg⁻¹ and 0, 100, and 250 mg Cd kg⁻¹) in the soil, which was then treated with MSW at a rate of 10% or PM at a rate of 7.6%. The pH and biochemical parameters were measured at 0 and 120 days. An unamended and no-polluted soil was used as control. Compared with the non-polluted soil, for the 250 mg Cd kg⁻¹ treatment the microbial biomass-C, dehydrogenase, urease, β-glucosidase, phosphatase, and arylsulphatase activities decreases 23%, 26.2%, 36%, 34.8%, 18.4%, and 15.8%, respectively, whereas for 250 mg Cr kg⁻¹ treatment the biochemical parameters were slightly lowest than for 250 mg Cd kg⁻¹ treatment. For 250 mg Cr kg⁻¹ soil + 250 mg Cd kg⁻¹ soil treatment, the inhibition percentages of the biochemical parameters increased. After the application of organic wastes in Cr + Cd polluted soil, the inhibition of biochemical properties was greater with the MSW amendment than with PM, possibly due to its higher humic acid concentration.     

Suppressive effect of magnesium oxide materials on cadmium accumulation in winter wheat grain cultivated in a cadmium-contaminated paddy field under annual rice–wheat rotational cultivation

The effectiveness of two kinds of magnesium oxide (MgO) materials, commercial MgO (2250 kg ha⁻¹) and a material derived from MgO and magnesium silicate minerals named ‘MgO-SH-A’ (2250 and 4500 kg ha⁻¹1), in suppression of uptake and accumulation of cadmium (Cd) into grain of winter wheat (Triticum aestivum L. cv. Ayahikari) was examined in a Cd-contaminated alluvial paddy field under annual rice–wheat rotational system. The MgO materials were mixed into the plough-layer soil only once prior to the preceding rice cultivation. Cadmium concentration in wheat grain produced from the non-amendment control exceeded the maximum limit of Cd in wheat grain adopted by FAO/WHO (0.2 mg kg⁻¹). All of the treatments with the MgO materials significantly lowered plant available Cd fraction in the plough-layer soil. However, only the treatment with the commercial MgO at 2250 kg ha⁻¹ produced wheat grain whose Cd concentration was not only significantly lower than that from the control but also less than 0.2 mg kg⁻¹. It is suggested that the significant suppressive effect of the commercial MgO on Cd accumulation in wheat grain would be mainly attributed to its high soil neutralizing capacity as compared to that of MgO-SH-A.     

The effect of EDDS addition on the phytoextraction efficiency from Pb contaminated soil by Sedum alfredii Hance

Present study reports the results of three pot experiments, conducted to investigate the chelate-assisted phytoextraction of Pb contaminated soils. The optimum phytoextraction was observed when 2.5 mM ethylene diamine disuccinic acid (EDDS) was added in single dosage for 14 days to low Pb soil (treated with 400 mg kg⁻¹ soil). On the contrary, for high Pb soil (treated with 1200 mg kg⁻¹ soil), 5 mM EDDS concentration in single dosage for 10 days produced better results. Post-harvest effects of EDDS on the concentrations of available Pb and dissolved organic carbon (DOC) were significantly higher as compared with check (CK i.e. without EDDS addition), and consequently decreased with the passage of time. Our results suggested that chelate-assisted phytoextraction was more suitable for slightly contaminated soils.     

Preparation of a modified flue gas desulphurization residue and its effect on pot sorghum growth and acidic soil amelioration

A modified flue gas desulphurization residue (MFGDR) was prepared and its effects on sorghum growth and acidic soil amelioration were evaluated in this paper. The MFGDR was prepared by calcining a mixture of dry/semi-dry flue gas desulphurization (FGD) residue from a coal-fired power plant, sorted potash feldspar and/or limestone powder. The available nutrients from the MFGDR were determined with 4.91 wt% K⁺, 1.15 wt% Mg²⁺, 22.4 wt% Ca²⁺, 7.01 wt% Si⁴⁺ and 2.07 wt% SO₄²⁻-S in 0.1 mol L⁻¹ citric acid solution. Its pH value was held at 9.60 displaying slightly alkaline. The results of sorghum pot growth in both red and crimson acidic soil for 30 days indicated that adding the MFGDR at a dosage of 2 g kg⁻¹ in total soil weight would increase the growth rate of biomass by 24.3-149% (wet weight basis) and 47.3-157% (dry weight), the stem length and thickness increase by 5.75-22.1% and 4.76-30.9% in contrast with CK treatment for two test cuttings, respectively. The effect on sorghum growth was attributed to the increase of available nutrients, the enhancement of soil pH value and the reduction of aluminum toxicity in acidic soil due to the addition of the MFGDR. The experimental results also suggested that the MFGDR could be effectively used to ameliorate the acidic soil which is widely distributed throughout the southern China.     

The effects of carbon sources and micronutrients in whey and fermented whey on the kinetics of phenanthrene biodegradation in diesel contaminated soil

This paper demonstrates significant effects on phenanthrene degradation in diesel contaminated soil by the addition of organic amendments such as whey and fermented whey. Both amount of amendment added and mode of administration was shown to be decisive. There was a strong positive effect on the ¹⁴C-mineralization of phenanthrene by multiple (bi-weekly) additions of fermented whey 210 mg dw kg⁻¹ soil dw (FW multi) and also by single dose addition of 2100 mg dw sweet whey kg⁻¹ soil dw (SW high). The most prominent effects on phenanthrene degradation kinetics were a five to fifteen fold increase in the linear growth term (k₂) and a 23-27% increase in bioavailability factor S₀ for SW high and FW multi respectively. Also, total mineralization at the end of the experiment increased from 46% in the control to 66 and 71% respectively and the lag time was reduced from 21 to 15 days by multiple addition of fermented whey. The most significant stimulating effects on phenanthrene degradation kinetics could be attributed to lactate and vitamins. This study demonstrates a more complex dependence of carbon sources and growth factors for an aromatic compound such as phenanthrene in comparison to hexadecane.     

Natural and artificial radioactivity measurements in Eastern Black Sea region of Turkey

In the present work, naturally occurring radionuclides of ²²⁶Ra, ²³²Th and ⁴⁰K were measured in soil samples collected from the Eastern Black Sea region of Turkey. It was found that the activity concentrations ranged from 12 to 120 Bq kg⁻¹ for ²²⁶Ra, from 13 to 121 Bq kg⁻¹ for ²³²Th and from 204 to 1295 Bq kg⁻¹ for ⁴⁰K. Besides naturally occurring radionuclides, ¹³⁷Cs activity concentration was measured in soil, lichen and moss samples and it was found that ¹³⁷Cs activity concentration ranged from 27 to 775 Bq kg⁻¹ with for soil, from 29 to 879 Bq kg⁻¹ for lichen and from 67 to 1396 Bq kg⁻¹ for moss samples. Annual effective doses due to the naturally occurring radionuclides and ¹³⁷Cs were estimated. Ecological half-lives of ¹³⁷Cs in lichen and moss species were estimated. The decrease of the activity concentrations in the present measurements (2007) relative to those in 1993 indicated ecological half-lives between 1.36 and 2.96 years for lichen and between 1.35 and 2.85 years for moss species.     

Removal of acid orange 7 by guava seed carbon: A four parameter optimization study

The preparation of carbon from waste materials is a recent and economic alternative for the removal of dyes. In this study four samples of carbon were obtained by thermal treatment at 1000 °C using as precursor the guava seed with different particle sizes. The Taguchi method was applied as an experimental design to establish the optimum conditions for the removal of acid orange 7 in batch experiments. The chosen experimental factors and their ranges were: pH (2–12), temperature (15–35 °C), specific surface area (50–600 m² g⁻¹) and adsorbent dosage (16–50 mg ml⁻¹). The orthogonal array L₉ and the larger the better response category were selected to determine the optimum removal conditions: pH 2, temperature 15 °C, S_esp 600 m² g⁻¹ and dosage 30 mg ml⁻¹. Under these conditions a total removal of acid orange 7 was achieved. Moreover, the most significant factors were the carbon specific surface area and the pH. The influence of the different factors on the adsorption of acid orange 7 from solution is explained in terms of electrostatic interactions by considering the dye species and the character of the surface.     

Single and binary chromium(VI) and Remazol Black B biosorption properties of Phormidium sp.

Wastewaters of textile and leather dying industries may contain significant quantities of chromium(VI) ions besides anionic and water-soluble dyes. Moreover the temperature of these wastewaters may be a controlling parameter affecting the biosorption efficiency. In this study biosorption of chromium(VI) and Remazol Black B reactive dye by dried Phormidium sp., a thermophilic cyanobacterium, was studied as a function of initial chromium(VI) concentration and temperature in no dye and 100 mg l⁻¹ dye-containing media at an initial pH value of 2.0 at which the biomass exhibited the maximum chromium(VI) and dye uptakes. The decrease of both metal and dye uptakes with temperature indicated that the uptakes were exothermic in nature. Equilibrium uptake of chromium(VI) enhanced considerably with both chromium(VI) and 100 mg l⁻¹ dye concentrations. Moreover the presence of chromium(VI) also increased the uptake of dye. At 25 °C, 22.8 mg g⁻¹ chromium(VI) and 91.3 mg g⁻¹ dye were sorbed by the biomass in binary 100 mg l⁻¹ chromium(VI) and 100 mg l⁻¹ dye-containing medium. The Langmuir was the best suitable adsorption model for describing the biosorption of chromium(VI) individually and in dye-containing medium. The pseudo-second-order kinetic model described both the chromium(VI) and dye biosorptions kinetics accurately.     

Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives

In a laboratory study, formulations of 15% (w/w) of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and pozzolanic cement (PC) and additives: plasticizers cementol delta ekstra (PCDE) and cementol antikorodin (PCA), polypropylene fibers (PPF), polyoxyethylene-sorbitan monooleate (Tween 80) and aqueous acrylic polymer dispersion (Akrimal) were used for solidification/stabilization (S/S) of soils from an industrial brownfield contaminated with up to 157, 32,175, 44,074, 7614, 253 and 7085 mg kg⁻¹ of Cd, Pb, Zn, Cu, Ni and As, respectively. Soils formed solid monoliths with all cementitious formulations tested, with a maximum mechanical strength of 12 N mm⁻² achieved after S/S with CAC + PCA. To assess the S/S efficiency of the used formulations for multi-element contaminated soils, we propose an empirical model in which data on equilibrium leaching of toxic elements into deionized water and TCLP (toxicity characteristic leaching procedure) solution and the mass transfer of elements from soil monoliths were weighed against the relative potential hazard of the particular toxic element. Based on the model calculation, the most efficient S/S formulation was CAC + Akrimal, which reduced soil leachability of Cd, Pb, Zn, Cu, Ni and As into deionized water below the limit of quantification and into TCLP solution by up to 55, 185, 8750, 214, 4.7 and 1.2-times, respectively; and the mass transfer of elements from soil monoliths by up to 740, 746, 104,000, 4.7, 343 and 181-times, respectively.     

Zinc recovery and waste sludge minimization from chromium passivation baths

This work reports the feasibility of applying emulsion pertraction technology (EPT) aiming at zinc recovery and waste minimization in the zinc electroplating processes that include Cr (III) passivation. The assessment consists of firstly the lifetime extension of the passivation baths by selective removal of the tramp ions zinc and iron, and secondly, the recovery of zinc for further reuse. Spent passivation baths from a local industry were tested, being the major metallic content: Cr³⁺ 9000 mg L⁻¹, Zn²⁺ 12,000 mg L⁻¹, Fe³⁺ 100 mg L⁻¹. Working in a Liqui-Cel hollow fiber membrane contactor and using the extractant bis(2,4,4-trimethylpentyl) phosphinic acid, reduction of zinc and iron concentrations below 60 mg L⁻¹ and 2 mg L⁻¹, respectively were obtained, while trivalent chromium, the active metal that generates the passivation layer, was retained in the baths. Zinc was selectively transferred to an acidic stripping phase that in the experimental time reached a concentration of 157,000 mg L⁻¹. Zinc recovery by electrowinning from the acidic stripping phase without any pretreatment of the electrolyte solution provided a purity of 98.5%, matching the lower commercial zinc grade. As a result of the extension of the life time of the passivation bath, significant environmental advantages are derived such as minimization of the volume of hazardous wastes and savings in the consumption of raw materials.     

Morphology and photophysical properties of polymer thin films dispersed with dye nanoparticle

We prepared nanoparticles of an organic dye, acridine orange (AO), dispersed in poly(methacrylic acid) (PMA) films by spin-coating the solution of the two components. The surface of the AO/PMA films became bumpier with increasing AO concentration (c_AO). The absorption and fluorescence spectra of AO/PMA films exhibited a marked dependence on c_AO at low c_AO (c_AO < 2.1 × 10^− 1 mol kg^− 1), and were independent of c_AO at high c_AO (c_AO > 2.1 × 10^− 1 mol kg^− 1). The peak shift of fluorescence spectra with changing c_AO was as large as ∼ 100 nm.     

Novel modeling concept for evaluating the effects of cadmium and copper on heterotrophic growth and lysis rates in activated sludge process

A new modeling concept to evaluate the effects of cadmium and copper on heterotrophic growth rate constant (μ_H) and lysis rate constant (b_H) in activated sludge was introduced. The oxygen uptake rate (OUR) was employed to measure the constants. The results indicated that the μ_H value decreased from 4.52 to 3.26 d⁻¹ or by 28% when 0.7 mg L⁻¹ of cadmium was added. Contrarily the b_H value increased from 0.31 to 0.35 d⁻¹ or by 11%. When adding 0.7 mg L⁻¹ of copper, the μ_H value decreased to 2.80 d⁻¹ or by 38%. The b_H value increased to 0.42 d⁻¹ or by 35%. After regression, the inhibitory effect was in a good agreement with non-competitive inhibition kinetic. The inhibition coefficient values for cadmium and copper were 1.82 and 1.21 mg L⁻¹, respectively. The relation between the b_H values and heavy metal concentrations agreed with exponential type well. The heavy metal would enhance b_H value. Using these data, a new kinetic model was established and used to simulate the degree of inhibition. It was evident that not only the inhibitory effect on μ_H but also that the enhancement effect on b_H should be considered when heavy metal presented.     

Investigation of a sewage-integrated technology combining an expanded granular sludge bed (EGSB) and an electrochemical reactor in a pilot-scale plant

A sewage-integrated treatment system (SITS) for the treatment of municipal wastewater, consisting of an expanded granular sludge bed (EGSB) reactor to remove soluble organic matter and an electrochemical (EC) reactor to oxidize the NH₃-N, was evaluated. The performance of the EGSB reactor was monitored for 12 months in a pilot-scale plant. Iron shavings were added to the EGSB reactor on the sixtieth day to improve the removal efficiency of the chemical oxygen demand (COD), suspended solids (SS) and total phosphorus (TP). After the iron shavings were added, the effluent COD, SS and TP decreased from 104 to 46 mg L⁻¹, 21 to 8.6 mg L⁻¹ and 3.62 to 1.36 mg L⁻¹, respectively. Moreover, in the EC reactor, which was equipped with IrO₂/Ti anodes, the NH₃-N and total nitrogen (TN) concentrations decreased from 25 to 12 mg L⁻¹ and 29 to 15 mg L⁻¹, respectively. The NH₃-N was directly oxidized to N₂, resulting in no secondary pollution. The results demonstrated the possibility of removing carbon and nutrients in a SITS with high efficiency. The system runs efficiently and with a flexible operation, making it suitable for low-strength wastewater. The results and parameters presented here can provide references for the practical project.     

Tl-208, Pb-212, Bi-212, Ra-226 and Ac-228 adsorption onto polyhydroxyethylmethacrylate-bentonite composite

The adsorption of naturally occurring radionuclides (²⁰⁸Tl⁺, ²¹²Pb²⁺, ²²⁶Ra²⁺, ²¹²Bi³⁺ and ²²⁸Ac³⁺) onto Polyhydroxyethylmethacrylate-bentonite (PHEMA-B) composite was investigated. Experimentally obtained isotherms were evaluated with reference to Langmuir, Freundlich and Dubinin-Radushkevich (DR) models. The adsorption isotherms were L type of Giles classification proving that PHEMA-B had a high affinity adsorbent for the studied radionuclides. The Langmuir adsorption capacities (X_L) were in the order of ²²⁶Ra (2.8 MBq kg⁻¹)>²¹²Bi (0.4 MBq kg⁻¹)>²¹²Pb (0.3 MBq kg⁻¹)>²²⁸Ac and ²⁰⁸Tl (0.2 MBq kg⁻¹). The adsorption process was physical via complex formation after proton exchanger for which the adsorption energies obtained from DR model was evidence. The enthalpy and entropy changes were positive and the negative free enthalpy change was proof for the spontaneity of adsorption. The reusability tests for PHEMA-B for five uses demonstrated that the adsorbent could be reused after complete recovery of the loaded radionuclide ions by 1 M HCl. The chemical structure of the composite did not change after the reuses and storage foregoing.     

Aqueous two-phase systems: a new approach for the determination of p-aminophenol

A new method has been developed for the spectrophotometric determination of p-aminophenol (PAP) in water, paracetamol formulations and human urine samples with a recovery rate between 94.9 and 101%. This method exploits an aqueous two-phase system (ATPS) liquid-liquid extraction technique with the reaction of PAP, sodium nitroprusside and hydroxylamine hydrochloride in pH 12.0, which produces the [Fe₂(CN)₁₀]¹⁰⁻ anion complex that spontaneously concentrates in the top phase of the ATPS (K[Fe₂(CN)₁₀]¹⁰⁻=97.7). The ATPS does not require an organic solvent, which is a safer and cleaner liquid-liquid extraction technique for the determination of PAP. The linear range of detection was from 5.00 to 500 μg kg⁻¹ (R ≥ 0.9990; n = 8) with a coefficient of variation of 2.11% (n = 5). The method exhibited a detection limit of 2.40 μg kg⁻¹ and a quantification limit of 8.00 μg kg⁻¹. The ATPS method showed a recovery that ranged between 96.4 and 103% for the determination of PAP in natural water and wastewater samples, which was in excellent agreement with the results of the standard 4-aminoantipyrine method that was performed on the same samples.     

Feasibility of nutrient recovery from industrial sludge by vermicomposting technology

Transformation of industrial sludges into vermicompost is of double interest: on the one hand, a waste is converted into value added product, and, on the other, it controls a pollutant that is a consequence of increasing industrialization. This paper reports the feasibility of utilization of vermicomposting technology for nutrient recovery from industrial sludge in laboratory scale experiment employing Eisenia fetida earthworm. A total of nine vermireactors, having different percentage of wastewater treatment plant sludge of a food industry and cow dung, were established and monitored for fertilizer quality of vermicompost and growth and fecundity of the earthworms for 3 months. The earthworms were unable to survive in 100% FIS. There was a decrease in pH, organic carbon content, organic matter, C:N ratio, and increase in ash content, EC, nitrogen, potassium and phosphorus content in all the vermireactors. Total Kjeldhal nitrogen (TKN) content increased in the range of 12.2–28.7 g kg⁻¹ in different vermireactors after vermicomposting. C:N ratio was 1.59–5.24 folds lesser in final vermicomposts than initial raw substrate. The heavy metals’ content in final vermicomposts was higher than initial feed mixtures. Maximum worm biomass was observed in control, i.e., 100% CD (836 mg earthworm⁻¹) and the lowest in 30% CD + 70% FIS feed mixture (280 mg earthworm⁻¹). Cocoon production was started during 6–7th week in all feed mixture except in feed mixture no. 9. After 12 weeks maximum cocoons (57) were counted in 100% CD and minimum (2) in 30% CD + 70% FIS feed. The results indicated that food industry sludge could be converted into good quality manure by vermicomposting if mixed up to 30% with cow dung.     

Emissions of polycyclic aromatic hydrocarbons from fluidized and fixed bed incinerators disposing petrochemical industrial biological sludge

This study investigated the emissions of polycyclic aromatic hydrocarbons (PAHs) from two fluidized bed incinerators (FLBI_A and FLBI_B) and one fixed bed incinerator (FIBI) disposing biological sludge generated from the petrochemical industries in Taiwan. The results of 21 individual PAHs (including low (LM-PAHs), middle (MM-PAHs) and high molecular weight PAHs (HM-PAHs)) were reported. The LM-PAHs mainly dominated the total-PAHs in the stack flue gases, whereas the LM- and HM-PAHs dominated the total-PAHs in the bottom fly, fly ash and WSB effluent. Due to high carcinogenic potencies (= total-BaP_eq concentrations) in the bottom ash (195 ng g⁻¹) and WSB effluent (20,600 ng L⁻¹) of the FIBI, cautious should be taken in treating them to avoid second contamination. Lower combustion efficiency and elevated fuel/feedstock (F/W) ratio for the FIBI led to the highest total emission factor of total-PAHs (38,400 μg kg⁻¹). Lower total-PAH removal efficiencies of wet scrubber (WSB) (0.837–5.89%), cyclone (0.109–0.255%) and electrostatic precipitator (ESP) (0.032%) than those reported elsewhere resulted in high fraction in PAH contributions from the stack flue gases. Lower total-PAH emission factor was found for FLBI_A (2380 μg kg⁻¹ biological sludge) with higher combustion efficiency compared to those for FLBI_B (11,500 μg kg⁻¹) and FIBI (38,400 μg kg⁻¹ biological sludge), implying that combustion efficiency plays a vital role in PAH emissions.     

Graphene nanosheets-poly(o-aminophenol) nanocomposite for supercapacitor applications

Graphene nanosheets-poly(o-aminophenol) (POAP/GNS) nanocomposite was fabricated on a platinum surface by potential cycling. Voltammograms of the POAP/GNS/Pt electrode showed an excellent capacitive behavior accompanied with a redox transition with a mid-peak potential of 295 mV. The POAP/GNS nanocomposite displayed a specific capacitance as high as 281.1 F g⁻¹ at 0.1 A g⁻¹ which is almost three times higher than that of pure graphene. The specific energy and power of the nanocomposite material were 25.0 Wh kg⁻¹ and 34.8 W kg⁻¹, respectively. The nanocomposite retained more than 99% of the initial capacitance after 1200 charge/discharge cycles.     

Long-acting antibacterial activity of quaternary phosphonium salts functionalized few-layered graphite

Tetradecyl triphenyl phosphonium bromide (TTP) functionalized few-layered graphite (FG) was prepared to investigate the effects of phosphonium salts usage on the characteristics, morphology, thermal stability and long-acting antibacterial property of TTP functionalized FG (TTP-FG) by introducing different content of TTP into FG. The results showed that the phosphonium salt was intercalated into FG, and the basal spacing of TTP-FG was enlarged with the increasing of phosphonium salt content. TTP-FG-3 with 33.7% (mass fraction) of TTP, displayed excellent thermal stability and long-acting antibacterial activity with the minimal inhibitory concentrations against E. coli and S. aureus of 580 mg L⁻¹ and 285 mg L⁻¹ after 72 h soaking, respectively.     

Using response surface methodology to assess the effects of iron and spent mushroom substrate on arsenic phytotoxicity in lettuce (Lactuca sativa L.)

The effects of iron (Fe) and spent mushroom substrate (SMS) arsenic (As) phytotoxicity towards lettuce in artificial soils were investigated to separate the adverse soil parameters relating to As toxicity using a response surface methodology. SMS induced the root elongation of lettuce in both control and As-treated soils. However, in phytotoxicity test using a median effective concentration (EC₅₀) of As, Fe and the interaction between both parameters (Fe*SMS) significantly affected EC₅₀, which explained 71% and 23% of the response, respectively. The refined model was as follows: EC₅₀ of As (mg kg⁻¹) = 10.99 + 60.03 × Fe − 10.50 × Fe*SMS. The results confirmed that the soil parameters relating to the As mobility in soils were important factors affecting its toxicity. In conclusion, Fe significantly reduced the As phytotoxicity. However, although SMS enhanced the root elongation, SMS in As-treated soils decreased EC₅₀ of As on the root growth via its interaction with Fe. Despite the limitations of the artificial soils and range of parameters studied, the application of this statistical tool can be considered a powerful and efficient technique for interpretation and prediction of the complicated results caused by the interactions between many factors within the soil environments.