Heavy metals extraction from municipal solid waste incineration fly ash using adapted metal tolerant Aspergillus niger

This study focused on the adaptation of Aspergillus niger tolerating high concentration of heavy metals for bioleaching of fly ash. The Plackett-Burman design indicated that Al and Fe inhibited the growth of A. niger (AS 3.879 and AS 3.40) significantly. The single metal (Al and Fe) and multi-metals adapted AS 3.879 strain tolerated up to 3500 mg/L Al, 700 mg/L Fe, and 3208.1mg/L multi-metals, respectively. The order of metal extraction yield in two-step bioleaching of 60 and 70 g/L fly ash using Al adapted, multi-metals adapted and un-adapted AS 3.879 strains was as follows: multi-metals adapted>Al adapted>un-adapted. The multi-metals adapted strain grew with up to 70 g/L fly ash and secreted 256 mmol/L organic acids after 288 h, where 87.4% Cd, 64.8% Mn, 49.4% Zn and 45.9% Pb were dissolved. The extracted metals in TCLP test of the bioleached fly ash by multi-metals adapted strain were under the regulated levels in China.     

Metal accumulation and growth performance of Phaseolus vulgaris grown in fly ash amended soil

Phytoextraction of heavy metals from fly ash (FA) contaminated soil was evaluated using Phaseolus vulgaris var. T55. The results showed that electrical conductivity (EC), cation exchange capacity (CEC), organic carbon (OC) and organic matter (OM) of different amendments decreased with the addition of FA in the soil. The level of diethylene triaminepenta acetic acid (DTPA) extractable metals increased with increase in FA amendments up to 25%. However, Cr was found below detection limit in both the amendments. The metal accumulation in the plant tissues was found in the order of Fe>Zn>Mn>Co>Ni>Pb>Cu>Cd at 25% FA. Accumulation of Fe, Mn, Ni, Cu and Co was found more in the roots while Zn, Pb and Cd were more in the aerial parts.     

Fungal bioleaching of metals in preservative-treated wood

Twenty-four brown-rot and 10 white-rot fungi were screened to evaluate their applicability for detoxification of preservative-treated wood impregnated with copper and chromium (CC) salts. Brown-rot fungi generally showed higher tolerance towards copper inhibition than white-rot fungi. Additionally, brown-rot fungi were found to accumulate considerable quantities of oxalic acid (up to 44.3 mM) in liquid medium, while white-rot fungi generally accumulated only traces of this organic acid. Oxalic acid is a strong organic acid capable of complexing a variety of heavy metals. Four Antrodia vaillantii and two Poria placenta brown-rot strains that displayed both a high copper tolerance and a high oxalic acid production were selected for further study. The brown-rot fungi effectively decayed wood containing up to 4.4% CC causing corrected mass losses of up to 24.3% in 4 weeks. Fungal treatment was also found to promote extensive leaching of chromium (up to 52.4%), but only moderate leaching of copper (15.6% or less). These results indicate the potential of solid-state fermentation with copper-tolerant fungi for the remediation of preservative-treated wood. Improving the solubility of copper will be an important challenge for future research.     

Biosorption behavior of heavy metals in bioleaching process of MSWI fly ash by Aspergillus niger

In this study, it was considered that the biosorption of heavy metals by biomass might occur during the bioleaching of fly ash. This work is focused on the biosorption behavior of Al, Fe, Pb and Zn by Aspergillus niger during the bioleaching process. The fungal biomass was contacted with heavy metals solution which extracted from fly ash by using gluconic acid as leaching agent. The equilibrium time for biosorption was about 120 min. The biosorption experiment data at initial pH 6.5 was used to fit the biosorption kinetics and isotherm models. The results indicated that the biosorption of Al, Fe and Zn by A. niger biomass were well described by the pseudo-first order kinetic model. The pseudo-second order kinetic model was more suitable for that of Pb. The Langmuir isotherm model could well describe the biosorption of Fe, Pb and Zn while the Freundlich model could well describe the biosorption of Al. Furthermore, the biosorption of metal ions decreased evidently in the presence of fly ash as compared to that in the absence of fly ash. This research showed that although the biomass sorption occurred during the bioleaching process, it did not inhibit the removal of Al, Fe, Pb and Zn evidently from fly ash.     

水热法改性粉煤灰去除矿山酸性废水中金属离子

矿山酸性废水污染是由开采矿山和废弃矿山的所产生的重要环境问题。本文利用廉价的粉煤灰通过水热法改性制备了沸石吸附剂,研究了不同pH值、接触时间和吸附剂加入量条件下,矿山废水中的重金属离子去除效果。结果表明：pH值是影响重金属离子去除的重要因素,pH值在为7时,其对Pb²⁺、Zn²⁺、Cu²⁺去除率分别为100%、95.2%和95.8%;吸附剂对Cu²⁺的去除主要是由吸附和沉淀共同作用完成的,而Zn²⁺和Pb²⁺的去除主要依靠吸附作用。随着吸附剂加入量的增加,Pb²⁺、Zn²⁺、Cu²⁺的吸附率也随之增加,其最优加入量分别为20、25和30 g·L^-1。当Pb²⁺、Zn²⁺、Cu²⁺的吸附时间分别为20、40和50 min时,其去除率可分别可达94.2%、95.2%和98.2%。此外,还讨论了复合离子相互间强化和抑制作用。当3种离子同时存在时,其相互间的强化作用并不明显,但会呈现较显著的抑制作用。     

镉锌超积累植物伴矿景天焚烧飞灰的重金属浸出特性及安全处置

为探究超积累植物伴矿景天焚烧灰浸出回收有价金属的可行性,以800℃流化床焚烧旋风灰为材料,研究盐酸、硝酸、氯化铵以及不同浓度、液固比和浸出时间对飞灰中重金属浸出规律的影响,同时评价浸出残渣的安全性.结果 表明:浸提剂种类、浓度及液固比是影响浸出的重要参数,浸出时间的影响较小,酸性浸提剂浸出能力明显强于氯化铵盐溶液浸出;...     

Soil properties and turf growth on a sandy soil amended with fly ash

Field lysimeters of a sandy soil were amended to a depth of 100 mm with four rates (0, 5, 10 and 20%, wt/wt) of fly ash, and effects on soil water content, nutrient leaching, turf growth and nutrition, and uptake of trace elements by turf were assessed. Measurements were taken for 70 days for lysimeters either planted with rhizomes of Cynodon dactylon(L.) Pers., cv. `Wintergreen', or left bare. When irrigated daily, soil water content increased progressively with increasing rates of fly ash and leachate volumes were decreased by 17–52% for lysimeters containing fly ash amended soil. Fertiliser was applied equivalent to 28.4 g N m<sup>–2</sup> and 10.3 g P m<sup>–2</sup> for the entire 70 days (including pre-plant application). Macronutrient concentrations in leaf tissue were within levels regarded as sufficient. Total dry mass (root plus shoot) decreased when fertiliser application rates were reduced by 25%, irrespective of fly ash treatment. In `bare' lysimeters containing fly ash amended soil, cumulative leaching of NO₃ ^–, NH₄ ⁺and P were 0.32–0.88 of the values in non-amended soil. When planted with turf, leaching of those nutrients was minimal (equivalent to 3% of total N applied) and leaching loses did not differ among fly ash rates. Extractable soil P levels were increased 2.5–4.5-fold in the fly ash amended zone, compared with non-amended soil. Root mass in the top 100 mm was 1.2–1.5-fold larger for turf in fly ash amended soil, compared to non-amended soil. The Se concentrations were higher in leaf tissue grown in fly ash amended soil (being at most 0.63 g g^–1), but there was no effect of fly ash amended soil on As, Ba, B, Cd, Co, Cr, Cu, Pb, Hg, Mn, Ni, Ag or Zn in leaf tissues. Thus, fly ash amendment may be a suitable management option for turf culture on sandy soils, since fly ash improved soil water holding capacity and root growth in the amended zone.     

Hybridomas in a bioreactor cascade: modeling and determination of growth and death kinetics

Hybridomas were cultured under steady-state conditions in a series of two continuous stirred-tank reactors (CSTRs), using a serum-free medium. The substrate not completely converted in the first CSTR, was transported with the cells to the second one and very low growth rates, high death rates, and lysis of viable cells were observed in this second CSTR. These conditions are hardly accessible in a single vessel, because such experiments would be extremely time-consuming and unstable due to a low viability. In contrast to what is often observed in literature, kinetic parameters could thus be derived without the neccessity for extrapolation to lower growth rates. Good agreement with literature averages for other hybridomas was found. Furthermore, showing that the reactor series is a valuable research tool for kinetic studies under extreme conditions, the possibility to observe cell death under stable and defined steady-state conditions offers interesting opportunities to investigate apoptosis and necrosis. Additionally, a model was developed that describes hybridoma growth and monoclonal antibody production in the bioreactor cascade on the basis of glutamine metabolism. Good agreement between the model and the experiments was found.Abbreviation MAb Monoclonal antibody Nomenclature C _AConcentration of any (mol m^-3) component A D Dilution rate (s^-1) K _dDeath-rate constant (mol m^-3) K _lLysis-rate constant (mol m^-3) K _sMonod constant (mol m^-3) m Maintenance coefficient (mol cell^-1 s^-1) q Specific consumption (mol cell^-1 s^-1) or production rate t Time (s) X Cell concentration (cell m^-3) Y Yield coefficient (cell mol^-1) Greek symbols _d Specific death rate (s^-1) _l Specific lysis rate (s^-1) of viable cells _net Net specific growth (s^-1) rate _true True specific growth (s^-1) rate     

Effects of fly ash and Helminthosporium oryzae on growth and yield of three cultivars of rice

A 120-day greenhouse experiment was conducted to study the effects of various fly ash concentrations (0%, 20%, 40%, 60%, 80% and 100% vol/vol) with normal field soil and Helminthosporium oryzae on the growth and yield of three cultivars (Pusa Basmati, Pant-4 and Pant-10) of rice, Oryza sativa L. Application of 20% and 40% fly ash with soil caused a significant increase in plant growth and yield of all the three cultivars. Forty percent fly ash caused a higher increase in growth and yield than did 20%. Sixty percent, 80% and 100% fly ash had an adverse effect on growth and yield of all the three cultivars, the maximum being with 100% fly ash. Inoculation of H. oryzae had an adverse effect on the growth and yield, Pant-10 suffered higher damage by H. oryzae than Pusa Basmati and Pant-4. Pant-10 also exhibited higher infected leaf area and greater disease symptoms of H. oryzae than did Pusa Basmati and Pant-4. Plants grown in 100% fly ash suffered higher reductions in growth and yield with H. oryzae than plants grown in pure soil or in 20% or 40% fly ash. In general, plant growth was best in Pusa Basmati followed by Pant-4 and Pant-10, while yield was higher in Pant-4 followed by Pant-10 and Pusa Basmati.     

Impact of fly ash content and fly ash transportation distance on embodied greenhouse gas emissions and water consumption in concrete

Background, aim and scope  

Fly ash, a by-product of coal-fired power stations, is substituted for Portland cement to improve the properties of concrete and reduce the embodied greenhouse gas (GHG) emissions. Much of the world’s fly ash is currently disposed of as a waste product. While replacing some Portland cement with fly ash can reduce production costs and the embodied emissions of concrete, the relationship between fly ash content and embodied GHG emissions in concrete has not been quantified. The impact of fly ash content on embodied water is also unknown. Furthermore, it is not known whether a global trade in fly ash for use in concrete is feasible from a carbon balance perspective, or if transport over long distances would eliminate any CO₂ savings. This paper aims to quantify GHG emissions and water embodied in concrete (f′_c = 32 MPa) as a function of fly ash content and to determine the critical fly ash transportation distance, beyond which use of fly ash in concrete increases embodied GHG emissions.     

Reuse options for coal fired power plant bottom ash and fly ash

Reuse options for coal fly ash and coal bottom ash are reviewed in this paper. Although, significant quantities of coal fly ash and coal bottom ash are produced worldwide every year, less than 30 % of coal ash produced is reused. Coal ash is mainly reused in civil engineering applications such as road construction, embankments, construction materials, geo-polymer applications and in cement production. Other potential reuse options for coal ash include applications such as glass ceramics, water and wastewater treatment, agriculture as well as for making high value products (e.g. telescope mirrors, break-liners, fire proof products etc.). Considering that only a small fraction of coal ash is reused, other reuse options for commercial applications need to be explored.     

Factors affecting bioleaching kinetics of sulfide ores using acidophilic micro-organisms

Recovery of metal values from sulfide ores by use of acidophilic microorganisms is gaining importance. A number of commercial/pilot plants are setup to find out the techno-economic feasibility of the overall process. The main drawback in the process is the slow kinetics of dissolution of metal values from the sulfide ores. To make the technology e attractive the kinetics should be improved considerably. There are various factors which determine the overall kinetics such as bacterial activity and concentration, iron and sulfur oxidation, oxygen consumption, reactor design and nature of ore. A brief review has been made dealing with the above parameters     

Fungal wood decay in the presence of fly ash as indicated by gravimetrics and by extractability of low molecular weight volatile organic acids

A mycoremediation system of wood substrate and fungal inoculum was established on an organically poor fly ash deposit at the ?o?tanj Thermal Power Plant, Slovenia. A mini-block method with beech wood samples was used to select a suitable fungal isolate for inoculation into the mycoremediation system. Pleurotus ostreatus ZIM 76 proved to be the most appropriate for further tests. Compared to the mass loss in a non-contaminated medium, wood degradation with the selected fungal isolate was reduced by 51% on wood substrate contaminated with 17% (w/w) fly ash. The deterioration processes of wood chips on inoculated and non-inoculated experimental plots were studied by ionic chromatographic analyses of volatile organic acids in water extracts. The presence of P. ostreatus did not influence the concentrations of acetic and formic acids in water extracts from wood chips collected at experimental plots in different intervals from May 2006 to November 2007 comparing inoculated vs. non-inoculated plots.     

Coal fly ash utilization in agriculture: its potential benefits and risks

Over the past few decades there has been avid interest in developing the strategies for the utilization of Fly ash (FA). Major foci have been on its agricultural application. It is often economical to use FA as a soil amendment. The potential of FA as a resource material in agriculture is due to its specific physical properties like’s texture, water holding capacity, bulk density, pH etc., and contains almost all the essential plant nutrients. It can be used as in soil that cannot substitute the chemical fertilizers or organic manure it can be used in combination with these to get additional benefits in terms of improvement in soil physical characteristics, increased yields etc. The amount and method of FA application in soil would vary with the type of soil, the crop, grown, the prevailing agro climatic condition and also with the FA characteristics. Although, as an input material FA has many benefits for agriculture applications like, improvement of nutrient deficiency, effectively control various pests infesting etc., in contrast FA also contains number of toxic heavy metals and also have natural radioactivity materials in it. Therefore, proper attention should be given on some important areas related to FA utilization such as long term studies of impact of FA on soil health, heavy metal uptake, plant physiology and growth, crop quality, and continuous monitoring on the soil characteristics. While using FA in agriculture problem of heavy metal toxicity and leaching due to excess dose should also be kept in mind.     

Effects of fly ash incorporation on heavy metal accumulation, growth and yield responses of Beta vulgaris plants

Use of fly ash (FA) to agriculture is not always beneficial, however, utilization of lower concentration of FA as soil amendment is suitable for better management of few crops. The present study was conducted to study the effects of various concentrations of FA (0%, 5%, 10%, 15% and 20%) on heavy metal accumulation, growth, and yield responses of palak (Beta vulgaris L. var All Green H1). The results showed that application of FA caused significant reductions in growth, biomass and yield responses of B. vulgaris plants at different ages of observations. The concentrations of all the heavy metals increased significantly with increasing concentrations of FA. Metal pollution index (MPI) of both roots and shoots showed significant and negative relationships with the yield of B. vulgaris plants. The study concludes that B. vulgaris plant is sensitive to FA concentrations used in this study. It is further recommended that leafy vegetable like B. vulgaris is not a suitable crop to be grown in a region where FA is used for amendment of agricultural soils.     

Effects of different treatments of fly ash and mining soil on growth and antioxidant protection of Indian wild rice

The aim of the present study was investigation of the effects of fly ash and mining soil on growth and antioxidant protection of two cultivars of Indian wild rice (Oryza nivara and Oryza rufipogon) for possible phytoremediation and restoration of metal-contaminated site. In this study, Indian wild rice showed significant changes in germination, growth, and biochemical parameters after exposure to different ratio of fly ash and mining soil with garden soil. There was significant reduction of germination, fresh weight, dry weight, leaf chlorophyll content, leaf area, Special Analysis Device Chlorophyll (SPAD) Index, proteins, and activities of antioxidant enzymes in both cultivars of the wild rice grown in 100% fly ash and mining soil compared to the plants grown in 100% garden soil. Results from this study showed that in both cultivars of wild rice, all growth and antioxidant parameters increased when grown in 50% fly ash and mining soil. Taken together, Indian wild rice has the capacity to tolerate 50% of fly ash and mining soil, and can be considered as a good candidate for possible phytoremediation of contaminated soils.     

Metal phytoremediation potential of naturally growing plants on fly ash dumpsite of Patratu thermal power station,Jharkhand, India

Three naturally growing plants Ipomoea carnea, Lantana camara, and Solanum surattense were found in fly ash dumpsite of Patratu thermal power station, Jharkhand, India. They were assessed for their metal uptake potential. The fly ash was slightly alkaline with very less nitrogen and organic carbon but enriched with phosphorus and heavy metals. Lantana camara and Ipomoea carnea showed good translocation from root to shoot for most of the metals except Mn and Pb. The order of metal accumulation in stem of both the plants were Fe(205mg/kg)>Mn(65mg/kg)>Cu(22.35mg/kg)>Pb(6.6mg/kg)>Cr(3.05mg/kg)>Ni(1 mg/kg)>Cd(0.5 mg/kg) and Fe(741 mg/kg)>Mn(154.05 mg/kg)>Cu(20.75 mg/kg)>Pb(6.75 mg/kg)>Ni(4.0 mg/kg)>Cr(3.3mg/kg)>Cd(0.05mg/kg), respectively. But Solanum surattense accumulated most of the metals in roots. The order was in the following order, Mn (382.2mg/kg) >Fe (264.1mg/kg) > Cu (25.35mg/kg) >Pb (5.95 mg/kg) > Ni (1.9 mg/kg) > Cr (1.8mg/kg) > Cd (0.55 mg/kg). The order of Bioconcentration factor (BCF) in root and shoot followed almost the same order as, Mn>Fe>Ni>Pb>Cu>Cr≈ Cd in all the three species. ANOVA showed significant variation in metal accumulation by root and stem between the species. Finally, it can be concluded that Solanum surattense can be used as phytostabilizer and other two species as phytoextractor of metal for fly ash dumpsite reclamation.     

Phytoremediation efficiency of Eichhornia crassipes in fly ash pond

The present study was focused on field research to examine the phytoremediation potential of naturally grown Eichhornia crassipes in fly ash (FA) pond. Field results indicate the efficiency of E. crassipes for remediation of heavy metals from FA pond. The bioconcentration factor trend was Cr (3.75) > Cu (2.62) > Cd (1.05), and Cu (1.35) in root and stem, respectively. The survival and abundance growth of E. crassipes in the circumstance of heavy metal enriched FA pond is another highlight of the present research that reveals its toxitolerant characteristics. Thus, this lesson on phytoremediation proved that E. crassipes is a potential accumulator of Cu, Cr, and Cd from FA ponds and is a promising species for FA pond's remediation globally.     

The utilization of fly ash by two tube-building polychaetes

Benthic tube-building polychaetes which utilize sediment particles have been found to incorporate fly ash in their tubes. Experiments were conducted on North Sea specimens of Myriochele oculata Zachs and Pectinaria koreni (Malmgren) in artificial sediments offering a range of fly ash concentrations. A marked selection for non-ash particles was shown by Myriochele oculata, and a marginal selection against ash by Pectinaria koreni. It is suggested that this selection is based on the inorganic nature of fresh ash particles, assuming initial collection for feeding: as ash particles at the sea bed develop an organic component, such selection will disappear.