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1.
Phosphorus (P) in wastes from piggeries may contribute to the eutrophication of waterways if not disposed of appropriately. Phosphorus leaching, from three soils with different P sorption characteristics (two with low P retention and one with moderate P retention) when treated with piggery effluent (with or without struvite), was investigated using batch and leaching experiments. The leaching of P retained in soil from the application of struvite effluent was determined. In addition, P leaching from lime residues (resulting from the treatment of piggery effluent with lime to remove P) was determined in comparison to superphosphate when applied to the same three soils. Most P was leached from sandy soils with low P retention when effluent with or without struvite was applied. More than 100% of the filterable P applied in struvite effluent was leached in sandy soils with low P retention. Solid, inorganic forms of P (struvite) became soluble and potentially leachable at pH<7 or were sorbed after dissolution if there were sufficient sorption sites. In sandy soils with low P retention, more than 39% of the total filterable P applied in recycled effluent (without struvite) was leached. Soil P increased mainly in surface layers after treatment with effluent. Sandy soils pre-treated with struvite effluent leached 40% of the P retained in the previous application. Phosphorus decreased in surface layers and increased at depth in the soil with moderate P retention after leaching the struvite effluent pre-treated soil with water. The soils capacity to adsorb P and the soil pH were the major soil properties that affected the rate and amount of P leaching, whereas the important characteristics of the effluent were pH, P concentration and the forms of P in the effluent. Phosphorus losses from soils amended with hydrated lime and lime kiln dust residues were much lower than losses from soils amended with superphosphate. Up to 92% of the P applied as superphosphate was leached from sandy soils with low P retention, whereas only up to 60% of the P applied in lime residues was leached. The P source contributing least to P leaching was the lime kiln dust residue. The amount of P leached depended on the water-soluble P content, neutralising value and application rate of the P source, and the pH and P sorption capacity of the soil. 相似文献
2.
Environmental Science and Pollution Research - Phosphorus is an essential element in the food production chain, even though it is a non-renewable and limited natural resource, which is going to run... 相似文献
3.
The removal of pollutants in saline medium by the Fenton's reagent needs a more detailed investigation, since the presence of chloride may inhibit or retard degradation. Phenol was used as a model pollutant and the influence of some important process variables for the removal of total organic carbon and phenol were investigated, such as FeSO4 and H2O2 concentrations, pH and salinity. The reactivity of iron cations and alternative procedures of applying UV radiation (photo-Fenton) were evaluated. Phenol was fast and completely removed by the Fenton's process even in a high saline medium (50,000mg NaCll(-1)). However, TOC was only moderately or poorly removed in saline media, depending on the salt concentration. When the photo-Fenton process was used, mineralization was improved and high TOC removals were observed in moderately saline media (NaCl concentration < or =10,000mgl(-1)). For the highest NaCl concentration tested (50,000mgl(-1)) only a moderate TOC removal was observed (50%). 相似文献
4.
A solid waste from manganese dioxide industry was studied for possible use to remove color from dye containing effluents. Artificial mixtures with direct, basic and acid dyes were studied. This material was found to be an effective adsorbent for the class of direct dyes. 相似文献
5.
Background Olive mill wastewater (OMW) generated by the olive oil extracting industry is a major pollutant, because of its high organic
load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. Mediterranean countries are
mostly affected by this serious environmental problem since they are responsible for 95% of the worldwide oliveoil production.
There are many methods used for OMW treatment, such as adsorption, electro coagulation, electro-oxidation, biological degradation,
advanced oxidation processes (AOPs), chemical coagulation, flocculation, filtration, lagoons of evaporation and burning systems,
etc. Currently, there is no such economical and easy solution. The aim of this study was to evaluate the feasibility of decolourization
and removal of phenol, lignin, TOC and TIC in OMW by UV/H 2O 2 (AOPs). The operating parameters, such as hydrogen peroxide dosage, times, pH, effect of UV and natural sunlight were determined
to find the suitable operating conditions for the best removal. Moreover, there is no study reported in the literature related
to the use of UV/H 2O 2 and lime together in OMW treatment.
Methods OMW was obtained from an olive-oil producing plant (Muğla area of Turkey) which uses a modern production process. No chemical
additives are used during olive oil production. This study was realised by using two different UV sources, while taking the
time and energy consumption into consideration. These two sources were mercury lamps and natural sunlight. Before starting
AOPs experiments, one litre of OMW was treated by adding lime until a pH of 7.00. Then, 100 ml was taken from each sample,
and 1 to 10 ml of a 30% H 2O 2 (Riedel-deHaen) solution was added. These solutions in closed vessels were laid in the natural sunlight for a week and their
compositions and colour changes were analysed daily by UV-Vis spectrophotometer. At the end of the one-week period, they were
treated with lime. In this study, the effect of changes in the initial pH, times and H 2O 2 concentrations on removal was investigated. At the end of all experiments, changes in colour, phenol, lignin, TOC and TIC
concentrations were analysed according to standard methods.
Results and Discussion In the samples exposed to natural sunlight and having an H 2O 2/OMW ratio of 3 ml/100 ml, a significant colour removal was achieved approximately 90% of the time at the end of 7 days. When
the same samples were treated with lime (pH: up to 7), 99% efficiency was achieved. When phenol and lignin removals were examined
in the same concentration, phenol and lignin removal were found 99.5%, 35%, respectively. However, for maximum lignin removal,
more use of H 2O 2 (10 ml H 2O 2/100 ml OMW) was found to be necessary. Under these conditions, it was found that lignin can be removed by 70%, but to 90%
with lime, at the end of a seven-day period. Rate constants obtained in the experiments performed with direct UV were found
to be much higher than those of the samples exposed to natural sunlight (k a
lignin
= 0.3883 ≫ k b
lignin
= 0.0078; k a
phenol
= 0.5187 ≫ k b
phenol
= 0.0146). Moreover, it should be remembered in this process that energy consumption may induce extra financial burden for
organisations.
Conclusions It was found, in general, that colour, lignin, total organic carbon and phenol were removed more efficiently from OMW by using
H 2O 2 UV and lime OMW. Moreover, in the study, lime was found to contribute, both initially and after radical reactions, to the
efficiency to a great extent.
Recommendations and Perspectives Another result obtained from the study is that pre-purification carried out with hydrogen peroxide and lime may constitute
an important step for further purification processes such as adsorption, membrane processes, etc. 相似文献
6.
Integrated up-flow floating media system utilised sponge cube floating bed for microbial attachment and suspended solid clarification. The first reactor was operated under anaerobic condition where high organic removal of more than 85% was reached. It was followed by anoxic/aerobic floating media reactors or chemical coagulation/air stripping units. When biological post treatment was employed, overall organic removal efficiency was up to 98%. In case of chemical post treatment, alum was applied at optimal dose of 1.0 gL −1 with COD, SS and colour removal of 88%, 97% and 93%, respectively. The air stripping process further removed more than 75% of ammonia nitrogen, yielding comparable effluent qualities to the biological process. 相似文献
7.
The morphological characteristics as well as chemical composition of rice husks were evaluated by different techniques such as spectroscopy and thermogravimetry. The material, which is considered a by-product obtained from rice milling, was then investigated as a potential decontaminant of toxic heavy metals present in laboratory effluents. Studies using glass columns were carried out at room temperature employing 100 ml of synthetic solutions containing Cd(II) and Pb(II) at 100 mg l(-1) in order to study the effects of pH, flow rate and particle size on Cd(II) and Pb(II) adsorption. After establishing the optimised conditions, the potentiality of rice husks for removing Cd(II) and Pb(II) ions from 100 ml of laboratory effluent, presenting concentrations before treatment of 22 and 12 mg l(-1), respectively, was evaluated. The ability to take up other metals species, such as Al(III), Cu(II) and Zn(II), present in this effluent was also studied. According to the data obtained, under the optimised conditions (pH=4.0, flow rate of 8.0 ml min(-1) and < or =355 microm rice husk particle size), 30 g of husks were necessary to attain the permissible limits for effluent release, as recommend by the EPA, for those species evolved in this work (Al, Cd, Cu, Pb and Zn). 相似文献
8.
Adsorption isotherms for a selection of non-ionic surfactants on activated carbons indicated the effectiveness of the latter in the removal of these pollutants from secondary effluents. The removal efficiencies were found to be improved when the secondary effluent was first flocculated with ferric chloride. This effectively removed some 80% of the non-ionic surfactant in the effluent. Batch adsorption experiments with powdered activated carbon removed 97% of the surfactant at low carbon dosage. A granular carbon with the best adsorption capacity was selected for continuous-flow operation in which non-ionic surfactants, COD and anionic surfactant alkyl benzene sulphonate were monitored. The breakthrough capacity for the non-ionic surfactants was in excess of 6000 bed volumes throughput of flocculated, sand-filtered effluent in a laboratory scale carbon column. Such a procedure is suggested for the complete removal of such pollutants from effluents. 相似文献
9.
Granular activated carbon (GAC) exhaustion rates on pulp and paper effluent from South East Australia were found to be a factor of three higher (3.62 cf. 1.47 kg m −3) on Kraft mills compared to mills using Thermomechanical pulping supplemented by Recycled Fibre (TMP/RCF). Biological waste treatment at both mills resulted in a final effluent COD of 240 mg L −1. The dissolved organic carbon (DOC) was only 1.2 times higher in the Kraft effluent (70 vs. 58 mg L −1), however, GAC treatment of Kraft and TMP/RCF effluent was largely different on the DOC persisted after biological treatment. The molecular mass (636 vs. 534 g mol −1) and aromaticity (5.35 vs. 4.67 L mg −1 m −1) of humic substances (HS) were slightly higher in the Kraft effluent. The HS aromaticity was decreased by a factor of 1.0 L mg −1 m −1 in both Kraft and TMP/RCF effluent. The molecular mass of the Kraft effluent increased by 50 g mol −1 while the molecular mass of the TMP/RCF effluent was essentially unchanged after GAC treatment; the DOC removal efficiency of the GAC on Kraft effluent was biased towards the low molecular weight humic compounds. The rapid adsorption of this fraction, coupled with the slightly higher aromaticity of the humic components resulted in early breakthrough on the Kraft effluent. Fluorescence excitation-emission matrix analysis of the each GAC treated effluent indicated that the refractory components were higher molecular weight humics on the Kraft effluent and protein-like compounds on the TMP/RCF effluent. Although the GAC exhaustion rates are too high for an effective DOC removal option for biologically treated pulp and paper mill effluents, the study indicates that advanced organic characterisation techniques can be used to diagnose GAC performance on complex effluents with comparable bulk DOC and COD loads. 相似文献
10.
Removal of chloride from recycled cooling water is needed to reduce corrosion and prolong equipment life. Laboratory experiments have demonstrated that the ultra-high lime with aluminum (UHLA) process has the ability to achieve high chloride removal efficiency from recycled cooling water. In an effort to further understand the behavior of chloride in the UHLA process, a fundamental model of the chemical processes was developed. The purpose of this paper is to describe this equilibrium model and present values for solubility products of precipitated solids that have not been investigated previously. The model was based on PHREEQC and a new program called INVRS K was integrated with PHREEQC to calculate values of unknown or poorly defined equilibrium or kinetic constants using a Gauss-Newton nonlinear regression routine. Model predictions indicated that the results could be best described by assuming the formation of a solid solution of calcium chloroaluminate (Ca4Al2Cl2OH12), tricalcium hydroxyaluminate (Ca3Al2OH12), and tetracalcium hydroxyaluminate (Ca4Al2OH14). 相似文献
11.
Nitrate contamination in groundwater resources originates mainly from the excessive use of fertilisers and uncontrolled land discharges of treated wastewater. This can cause potential health hazards to infants and pregnant women, thus limiting the direct use of the groundwater resources for the human consumption in several parts of the world, including India. The conventional processes used to eliminate nitrate from water are ion exchange, reverse osmosis and electro-dialysis. The utility of these processes has been limited due to their expensive operation and subsequent disposal problem of the generated nitrate waste brine. This paper presents a comprehensive account of the methods/techniques used for the removal of nitrate ion from water during the last 10 years with special reference to the biological denitrification and fate of the metals in decontamination processes. 相似文献
12.
The ultra high-lime with aluminum process (UHLA) has the ability to remove sulfate and chloride in addition to other scale-forming materials from recycled cooling water. Laboratory experiments have demonstrated that the UHLA process can achieve high chloride removal from recycled cooling water, and an equilibrium model was developed to describe chemical behavior during chloride removal. This paper describes the influence of pH, temperature, and initial chloride concentration on chloride removal by UHLA and identifies the precipitated solids formed during treatment. The optimum pH for maximum chloride removal efficiency was found to be 12 +/- 0.2. Chloride removal efficiency was higher at a high initial chloride concentration than at a low initial chloride concentration with the chemical doses used. Solids formed during UHLA treatment were identified by x-ray diffraction as calcium chloroaluminate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. This supports the assumption of the equilibrium model that these compounds are present and form a solid solution. 相似文献
13.
Three wastewater samples from a pharmaceutical plant formulating medical ointments were subjected to lab-scale treatment by a Fenton-like system in combination with lime coagulation. All samples were plant pre-treated by adsorption/flocculation/filtration processes with utilization of bentonite, but the quality of effluents did not comply with the regulations for wastewater discharged to local sewerage. The optimization of Fenton-like oxidation demonstrated the highest process efficacy at H(2)O(2)/COD weight ratio of 2:1, H(2)O(2)/Fe(2+) molar ratio of 10:1 and 2h of treatment time. The fast pH decrease to acidic values approximately 3 during first min of oxidation for all effluents suggested that pH adjustment was unnecessary. Combination of Fe(III) precipitation and lime coagulation proved feasible to improve considerably COD and residual iron concentration reduction in pharmaceutical effluents. Additionally, considerable BOD(7) reduction and BOD(7)/COD ratio improvement of pharmaceutical wastewater samples was achieved by combined treatment. The application of Fenton-like oxidation with subsequent iron (III)/lime coagulation did not only enhance the quality of pharmaceutical effluents with different chemical characteristics and help to meet the requirements for wastewater discharged to sewage, but also improve the biodegradability of pharmaceutical effluents. 相似文献
14.
This work establishes methods of reducing the amount of methane produced from the anaerobic treatment of piggery wastewater by either reducing the storage time before solid/liquid separation or inhibiting the activity of methanogens in anaerobic wastewater treatment system. Experimental results showed these two methods can be adopted effectively to reduce methane production resulting from anaerobic piggery wastewater treatment. First, the wastewater must be processed using solid/liquid separation immediately after washing pig houses. This process can reduce by 62% the biogas production and indirectly decrease the methane production from the anaerobic wastewater treatment reactor. Second, adding 10 mg L(-1) bromochloromethane (BCM) daily into the anaerobic wastewater treatment reactor can significantly reduce the amount of biogas and methane produced during the anaerobic fermentation process. Furthermore, biogas production can be completely inhibited after 4 days. Adding BCM (< or =10 mg L(-1)) to wastewater only slightly affected the efficiency of the anaerobic wastewater treatment process. Results in this study can provide the basis for further research on reduction of the amount of methane produced from anaerobic wastewater treatments. 相似文献
15.
Due to its adverse impact on health, as well as its global distribution, long atmospheric lifetime and propensity for deposition in the aquatic environment and in living tissue, the US Environmental Protection Agency (US EPA) has classified mercury and its compounds as a severe air quality threat. Such widespread presence of mercury in the environment originates from both natural and anthropogenic sources. Global anthropogenic emission of mercury is evaluated at 2000 Mg year−1. According to the National Centre for Emissions Management (Pol. KOBiZE) report for 2014, Polish annual mercury emissions amount to approximately 10 Mg. Over 90% of mercury emissions in Poland originate from combustion of coal. The purpose of this paper was to understand mercury behaviour during sub-bituminous coal and lignite combustion for flue gas purification in terms of reduction of emissions by active methods. The average mercury content in Polish sub-bituminous coal and lignite was 103.7 and 443.5 μg kg−1. The concentration of mercury in flue gases emitted into the atmosphere was 5.3 μg m−3 for sub-bituminous coal and 17.5 μg m−3 for lignite. The study analysed six low-cost sorbents with the average achieved efficiency of mercury removal from 30.6 to 92.9% for sub-bituminous coal and 22.8 to 80.3% for lignite combustion. Also, the effect of coke dust grain size was examined for mercury sorptive properties. The fine fraction of coke dust (CD) adsorbed within 243–277 μg Hg kg−1, while the largest fraction at only 95 μg Hg kg−1. The CD fraction < 0.063 mm removed almost 92% of mercury during coal combustion, so the concentration of mercury in flue gas decreased from 5.3 to 0.4 μg Hg m−3. The same fraction of CD had removed 93% of mercury from lignite flue gas by reducing the concentration of mercury in the flow from 17.6 to 1.2 μg Hg m−3. The publication also presents the impact of photochemical oxidation of mercury on the effectiveness of Hg vapour removal during combustion of lignite. After physical oxidation of Hg in the flue gas, its effectiveness has increased twofold. 相似文献
16.
The sorption of lead ions from aqueous solution onto chitosan has been studied. Equilibrium studies have been carried out to determine the capacity of chitosan for lead ions. The effects of solution pH and chitosan particle size on the sorption capacity have been studied.The experimental data were analyzed using three equilibrium isotherm correlations, namely, Langmuir, Freundlich and Redlich-Peterson equations. The linear correlation coefficients were determined for each isotherm and the Freundlich provided the best fit. In addition, error functions have been used to determine the alternative single component equilibrium isotherm parameters by non-linear regression due to the inherent bias in using the correlation coefficient from the linearization. This technique enables the "best fit" isotherm parameters to be used in the equilibrium equations for the sorption of lead ions on chitosan within the limits and assumptions of the various error analysis methods. 相似文献
17.
The effect of ozone fumigation on the reduction of difenoconazole residue on strawberries was studied. Strawberries were immersed in 1.0 L of aqueous solution containing 400 μL of the commercial product (250 g L ?1 of difenoconazole) for 1 min. Then, they were dried and exposed to ozone gas (O 3) at concentrations of 0.3, 0.6 and 0.8 mg L ?1 for 1 h. The ozone fumigation treatments reduced the difenoconazole residue on strawberries to concentrations below 0.5 mg kg ?1, which corresponds to a 95% reduction. The strawberries treated with ozone and the control group, which was not treated with ozone, were stored at 4°C for 10 days. Some characteristics of the fruit were monitored throughout this period. Among these, pH, weight loss and total color difference did not change significantly ( P > 0.05). The fumigation with ozone significantly affected the soluble solids, titratable acidity and ascorbic acid content (vitamin C) of the strawberries preventing a sharp reduction of these parameters during storage. 相似文献
18.
The discharge of effluents and toxic compounds into aquatic systems represents a growing environmental problem involving an impact on water ecology and potential effect on human health. Most municipal wastewaters are complex mixtures; their complexity led as to carry out a hazard assessment using chemical analyses and biological tests.This study investigates biochemical alteratiobns in two sentinel organisms, the Anodonta cygnea mussel and the Xenopus laevis frog exposed for different lengths of time to various concentrartion of wastewater of the S. Antonino Ticino treatment plant. The results point out the long-life of toxic compounds. 相似文献
19.
This work examines the performance of a hydrous ferric oxide (HFO) reactive filtration (RF) process with coupled chemically enhanced secondary treatment (RECYCLE) for phosphorus removal from municipal wastewater (HFO-RF-RECYCLE). A 3-month, 0.95-ML/d (0.25-mgd) demonstration of HFO-RF-RECYCLE was performed at a municipal wastewater treatment plant equipped with oxidation ditches and secondary clarifiers. Influent to the plant averaged 6.0 mg/L phosphorus, with a tertiary effluent average of 0.011 mg/L phosphorus. Iron doses to the plant were low, at 5 mg/L. Inline recycling of HFO solution rejects to the plant influent resulted in a maximum 90.3%, dose-dependent reduction of phosphorus in the secondary effluent at 4.5 ML/d (1.2 mgd). Other results included reduction of total suspended solids and turbidity. A mass balance analysis was performed. We conclude that HFO-RF-RECYCLE may allow very low levels of phosphorus discharge from municipal wastewater treatment plants with a ferric-iron-based tertiary filtration process and residual recycling. 相似文献
20.
The removal mechanism of a hydrous ferric oxide (HFO) reactive filtration (RF) process with coupled chemically enhanced secondary treatment (RECYCLE) for phosphorus removal from municipal wastewater (HFO-RF-RECYCLE) was examined. A 0.95-ML/d (0.25-mgd) demonstration of HFO-RF-RECYCLE was performed at a municipal wastewater treatment plant equipped with oxidation ditches and secondary clarifiers. Influent to the plant averaged 6.0 mg/L phosphorus, with a 3-month tertiary effluent average of 0.011 mg/L phosphorus. In addition to aqueous geochemical modeling, experiments with surface charge, scanning electron microscopy, adsorptive capacity, thermal desorption, and most probable number of iron(III)-reducing bacteria were performed on samples from the system, to determine the major phosphorus-removal pathways. Results suggest that, in addition to filtration of particulate phosphorus, the low tertiary effluent total phosphorus result was achieved by adsorption. 相似文献
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