Pollutants In Sludge Research Articles

Assessment of the Health Risk Induced by Accumulated Heavy Metals from Anaerobic Digestion of Biological Sludge of the Lettuce.

Heavy metals are a group of pollutants in biological sludge. Many agencies regulated guidelines for heavy metal concentrations for various applications of sludge such as agricultural application. In this study, we tried to determine heavy metal fate after anaerobic digestion. Additionally, we determined the bioaccumulation rate of heavy metals in lettuce cultivated on a sludge-applied land. Heavy metal (As, Pb, Hg, Cd) contents of solid and liquid parts of raw and anaerobically digested sludge were separately measured by ICP-OES. For this purpose, the samples were digested using nitric acid, hydrochloric acid, and boric acid. Then, the raw and anaerobically digested sludge were used for cultivation of lettuce in separate farms. The heavy metal concentrations in the harvested lettuce were measured by the same procedure. The results showed that the main part of heavy metals in the raw sludge was in the liquid part (67%), while, the main part of heavy metals in the anaerobically digested samples was in the solid part of the sludge. Because of washout of dissolved heavy metals in the liquid part of the sludge, the lettuce cultivated by anaerobically digested sludge had higher content of the heavy metals in comparison to that of the lettuce cultivated by the raw sludge. This study showed that application of anaerobically digested sludge can increase the bioaccumulation rate of heavy metals in the crops and induce more human health risk.

Remediation of Cadmium Toxicity on Alfalfa (Medicago sativa L.) Using Biochar as a Bioadsorbent, Rhizobium meliloti and Arbuscular Mycorrhizal Fungi as Biofertilizers

Contamination of agricultural soil is becoming an increasingly serious problem because of long-term exposure to pollutants in irrigation water, sludge, fertilizers, and pesticides. Cadmium (Cd) is one of the most dangerous and potentially toxic metals. Pollution by Cd is especially significant as contaminated soils are used for agriculture; this metal is easily absorbed from soils into crops, inhibiting plant growth and nutrient uptake. So, the present study aimed to elucidate the effect of accumulation Cd over the permissible limits on growth of higher plants, e.g., alfalfa and soil microorganisms, e.g., rhizobium bacteria and arbuscular mycorrhiza fungi. In this study we also attempted to find an optimum solution for the problem of soil pollution with Cd through the application of biochar (BC) as bioadsorbent, rhizobia, (Rh) and arbuscular mycorrhizal fungi (AMF) as biofertilizers. CdCl2 was applied in a pot experiment in presence and absence of BC, AMF and Rh. Cd negatively affected alfalfa growth and yield, content of essential minerals such as N, P, K, Ca and Mg in leaves and roots, activity of nodules nitrogenase and rhizosphere dehydrogenase. AMF colonization % and the total microbial count decreased under Cd stress. Application of BC, AMF and Rh individually or in combination improved alfalfa growth, leaf and root content of essential minerals, fungal population and the microbial count. On the other side, these treatments reduced Cd uptake and translocation from roots to seeds. Solo application of BC contributed in Cd immobilization through the metal adsorption and increasing soil alkalinity. Application of BC together with AMF and Rh significantly promoted alfalfa growth and yield, the leaf and root content of mineral ions, the fungal populations and the microbial count compared to control and Cd stressed plants.

Native plant colonization of brownfield soil and sludges: effects on substrate properties and pollutant mobility

Phytostabilization with native plant species might represent an economically more realistic and cost-effective option than excavation, soil washing, and sludge disposal for rehabilitation of degraded and polluted industrial areas. This work was done to assess the changes induced by native plant revegetation in the chemical properties and mobility-bioavailability of Pb and Zn pollutants of soil and post-washing sludges from an Italian brownfield site of national interest. A 5-year native plant revegetation of polluted soil and relative post-washing sludges from a steel plant was achieved in situ and ex situ in pot and in the presence and absence of peat as organic amendment. During the experiment, the vegetation growth was monitored (Adamo et al. In Int J Environ Sci Technol 12(6):1811–1824, 2015). Before and after plant growth, the substrates were studied for pH, organic carbon, and carbonate contents. Lead, Zn, and other metal mobility and leachability were investigated by water extraction. The metal bioavailability was estimated by diethylenetriaminepentaacetic acid (DTPA) extraction at pH 7.3. Sequential extractions (BCR procedure) were used to fractionate Pb and Zn in soil main geochemical forms. Plant ability to uptake metals was evaluated on the three most representative species: Bituminaria bituminosa, Daucus carota, and Dactylis glomerata. After 5 years of revegetation with native plants, the substrate pH and organic carbon content were respectively decreased and increased by plant growth, with changes masked by peat treatments. Although metal pollutants in both substrates were characterized by low water solubility and DTPA availability, after plant growth, an increase of rhizospheric Zn, Cu, Fe, and Mn solubility in H2O was detected. According to metal speciation, Pb and Zn were largely occluded in easily reducible manganese/iron oxides and trapped in the mineral structure of silicates, with no visible changes of distribution after plants. Water extraction always underestimated plant uptake, whereas DTPA and sequential extractions better predicted Pb and Zn uptake. Despite the original extremely low mobility and bioavailability of metal pollutants in both soil and post-washing sludges, the acidification and increase of organic carbon content induced by peat amendments and plant growth enhance the solubility in water of metal-containing compounds. Therefore, attention must be paid to these effects in the long period. A continuous monitoring of the changes of pollutant mobility-bioavailability induced by native plant revegetation of brownfields is crucial to prevent risks to the surrounding environment and human health.

Disposal Situation of Sewage Sludge from Municipal Wastewater Treatment Plants (WWTPs) and Assessment of the Ecological Risk of Heavy Metals for Its Land Use in Shanxi, China.

Land use of sewage sludge is the primary disposal method in Shanxi, accounting for 42.66% of all. To determine the ecological risk of heavy metals in sewage sludge, contents of seven heavy metals in sewage sludge from 9 municipal waste water treatment plants (WWTPs) that had the highest application for land use were determined. The order of the measured concentrations was: Zn > Cr > Cu > Ni > Pb > As > Cd, and all heavy metals contents were within the threshold limit values of the Chinese Control Standards for Pollutants in Sludge from Agriculture Use (GB4284-84). Four indices were used to assess the pollution and the ecological risk of heavy metals. By the mean values of the geoaccumulation index (Igeo), heavy metals were ranked in the following order: Cd > Zn > Cu > As > Cr > Ni > Pb. The values showed that the pollution of Zn in station 3 and Cd in station 1, 2, 3, 4, 8 and 9 were heavily; Cu in station 8 and 9, Zn in station 1, 2, 4, 8 and 9 and Cd in station 5 and 7 were moderately to heavily, and the accumulation of other heavy metals were not significant. The single-factor pollution index (PI) suggested that none of the stations had heavy metals contamination, except for Cu in station 9, Zn in station 3 and 8, and Cd in station 1 and 9, which were at a moderate level. According to the results of the Nemerow’s synthetic pollution index (PN), sewage sludge from all stations was safe for land use with respect to heavy metals contamination, except for stations 3, 8 and 9, which were at the warning line. The monomial potential ecological risk coefficient () revealed that heavy metals ecological risks in most stations were low. However, station 9 had a moderate risk for Cu; station 6 had a moderate risk, stations 5 and 7 had high risk, other stations had very high risk for Cd. According to the results of the potential ecological risk index (RI), station 1, 8 and 9 had high risk; station 2, 3, 4, 5 and 7 had a moderate risk, and station 6 had a low risk. The preliminary results indicated that the potential risk of land exposure to heavy metals in sewage sludge was relatively low, with Zn and Cd as the main contributor to the ecological risk for the applying of sewage sludge on land. Additionally, stations 3, 8 and 9 require more attention regarding the land applications related to heavy metals pollution.

Visible light driven photocatalytic degradation of organic pollutants in wastewater and real sludge using ZnO–ZnS/Ag 2 O–Ag 2 S nanocomposite

Visible light active ZnO–ZnS/Ag2O–Ag2S nanocomposite was synthesized for the photocatalytic decomposition of 2-chlorophenol (2-CP) and complex organic compounds in real sludge. The synthesized catalyst was characterized by X-ray diffraction, Scanning electron microscopy, Raman, UV–visible absorption spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic degradation of 2-CP was highly dependent on the solution pH, initial pollutant concentration and reaction time. The adsorption of 2-CP also plays a vital role in its degradation. The maximum interaction and degradation of 2-CP was found at pH 5. The photocatalytic decomposition of 2-CP decreased from 96 to 55% as its concentration increased from 10 to 100 mg/L. Furthermore, the ZnO-ZnS/Ag2O–Ag2S photocatalyst showed a significant enhancement in sludge solubilization, while the soluble COD increased by more than two times of its initial concentration. About 43% increase in the biogas production (anaerobic) was observed form photocatalytically pretreated sludge compared to raw sludge. These results suggest that the synthesized nanomaterial is an efficient catalyst that can be used for multiple applications such as the degradation of toxic pollutants in wastewater and solubilization of sludge for biogas production.

Linking toxicity profiles to pollutants in sludge and sediments

Obtaining a complex picture of how pollutants synergistically influence toxicity of a system requires statistical correlation of chemical and ecotoxicological data. In this study, we determined concentrations of eight potentially toxic metals (PTMs) and four groups of organic pollutants in 15 sewage sludge and 12 river sediment samples, then linked measured contaminant concentrations to the toxicity of each matrix through constrained correspondence analysis (CCA).In sludge samples, Hg, As, hexachlorohexane (HCH), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) influenced the toxicity profiles, with the first four having significant effects and HBCD being marginally significant. In sediment samples, Hg, As, PBDEs, hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT), HBCD, HCH and polycyclic aromatic hydrocarbons (PAHs) were found to explain toxicity profiles with Hg, As, PBDEs, HCB, DDT, HBCD, and HCH having significant effects and PAHs being marginally significant. Interestingly, HCH was present in small amounts yet proved to have a significant impact on toxicity. To the contrary, PAHs were often present in high amounts, yet proved to be only marginally significant for sediment toxicity. These results indicate that statistical correlation of chemical and ecotoxicological data can provide more detailed understanding of the role played by specific pollutants in shaping toxicity of sludge and sediments.

Uncertainty in degradation rates for organic micro-pollutants during full-scale sewage sludge composting

Composting can potentially remove organic pollutants in sewage sludge. When estimating pollutant removal efficiency, knowledge of estimate uncertainty is important for understanding estimate reliability. In this study the uncertainty (coefficient of variation, CV) in pollutant degradation rate (K1) and relative concentration at 35days of composting (C35/C0) was evaluated. This was done based on recently presented pollutant concentration data, measured under full-scale composting conditions using two different sampling methods for a range of organic pollutants commonly found in sewage sludge. Non-parametric statistical procedures were used to estimate CV values for K1 and C35/C0 for individual pollutants. These were then used to compare the two sampling methods with respect to CV and to determine confidence intervals for average CV. Results showed that sampling method is crucial for reducing uncertainty. The results further indicated that it is possible to achieve CV values for both K1 and C35/C0 of about 15%.

Polycyclic Aromatic Hydrocarbon Affects Acetic Acid Production during Anaerobic Fermentation of Waste Activated Sludge by Altering Activity and Viability of Acetogen.

Till now, almost all the studies on anaerobic fermentation of waste activated sludge (WAS) for bioproducts generation focused on the influences of operating conditions, pretreatment methods and sludge characteristics, and few considered those of widespread persistent organic pollutants (POPs) in sludge, for example, polycyclic aromatic hydrocarbons (PAHs). Herein, phenanthrene, which was a typical PAH and widespread in WAS, was selected as a model compound to investigate its effect on WAS anaerobic fermentation for short-chain fatty acids (SCFAs) accumulation. Experimental results showed that the concentration of SCFAs derived from WAS was increased in the presence of phenanthrene during anaerobic fermentation. The yield of acetic acid which was the predominant SCFA in the fermentation reactor with the concentration of 100 mg/kg dry sludge was 1.8 fold of that in the control. Mechanism exploration revealed that the present phenanthrene mainly affected the acidification process of anaerobic fermentation and caused the shift of the microbial community to benefit the accumulation of acetic acid. Further investigation showed that both the activities of key enzymes (phosphotransacetylase and acetate kinase) involved in acetic acid production and the quantities of their corresponding encoding genes were enhanced in the presence of phenanthrene. Viability tests by determining the adenosine 5'-triphosphate content and membrane potential confirmed that the acetogens were more viable in anaerobic fermentation systems with phenanthrene, which resulted in the increased production of acetic acid.

Analytical methodologies based on LC–MS/MS for monitoring selected emerging compounds in liquid and solid phases of the sewage sludge

In this work, two analytical methodologies based on liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) were developed for quantification of emerging pollutants identified in sewage sludge after a previous wide-scope screening. The target list included 13 emerging contaminants (EC): thiabendazole, acesulfame, fenofibric acid, valsartan, irbesartan, salicylic acid, diclofenac, carbamazepine, 4-aminoantipyrine (4-AA), 4-acetyl aminoantipyrine (4-AAA), 4-formyl aminoantipyrine (4-FAA), venlafaxine and benzoylecgonine. The aqueous and solid phases of the sewage sludge were analyzed making use of Solid-Phase Extraction (SPE) and UltraSonic Extraction (USE) for sample treatment, respectively. The methods were validated at three concentration levels: 0.2, 2 and 20μgL−1 for the aqueous phase, and 50, 500 and 2000μgkg−1 for the solid phase of the sludge. In general, the method was satisfactorily validated, showing good recoveries (70–120%) and precision (RSD<20%). Regarding the limit of quantification (LOQ), it was below 0.1μgL−1 in the aqueous phase and below 50μgkg−1 in the solid phase for the majority of the analytes. The method applicability was tested by analysis of samples from a wider study on degradation of emerging pollutants in sewage sludge under anaerobic digestion.The key benefits of these methodologies are:• SPE and USE are appropriate sample procedures to extract selected emerging contaminants from the aqueous phase of the sewage sludge and the solid residue.• LC–MS/MS is highly suitable for determining emerging contaminants in both sludge phases.• Up to our knowledge, the main metabolites of dipyrone had not been studied before in sewage sludge.

PAHs content of sewage sludge in Europe and its use as soil fertilizer

The European Commission has been planning limits for organic pollutants in sewage sludge for 14years; however no legislation has been implemented. This is mainly due to lack of data on sewage sludge contamination by organic pollutants, and possible negative effects to the environment. However, waste management has become an acute problem in many countries. Management options require extensive waste characterization, since many of them may contain compounds which could be harmful to the ecosystem, such as heavy metals, organic pollutants. The present study aims to show the true European position, regarding the polycyclic aromatic hydrocarbons (PAHs) content of sewage sludge, by comparing the Italian PAHs content with European Union countries, and at assessing the suitability of sewage sludge as soil fertilizer. The FOCUS Pearl model was used to estimate the concentration of benzo [a] pyrene (B(a)Pyr), the most toxic PAH in soil, and its exposure to organisms was then evaluated. The simulated B(a)Pyr and PAHs, expressed as B(a)Pyr, concentrations in soil were much lower than the B(a)Pyr’s most conservative lowest observable effect concentration (LOEC) for soil organisms. Furthermore, the results obtained indicate that it is more appropriate to apply 5tha−1 sewage sludge annually than 15tha−1 triennially. Results suggest, the EU maximum recommended limit of 6mgkg−1 PAHs in sewage sludge, should be conservative enough to avoid groundwater contamination and negative effects on soil organisms.

Non-target screening of organic pollutants in sediments and sludges using gas chromatography-mass spectrometry and automated mass spectral deconvolution

A screening method in the combination of ultrasonic extraction, gas chromatography-mass spectrometry detection and automated mass spectrometry deconvolution technique was developed for non-target screening of non-polar and weak polar pollutants in sediments and sludges. The samples were extracted by ultrasonication for 20 min using dichloromethane for three times. The extraction solutions were cleaned-up by gel permeation chromatography and a silica gel column, and then 3 g of copper powder was used to remove the sulfur by ultrasonication for 10 min. Parallel experiments were carried out for 5 times and the RSDs were ranged from 5.8% to 14.9%. Automated mass spectral deconvolution & identification system (AMDIS) would improve the resolution of overlapping peaks, and identify the pure mass spectrum of the analytes in the cases of stronger background interference and co-extracted substances covering. Standard spectrum databases, such as NISTDRUG, NISTEPA, NISTFDA, Mass Spectral Library, etc, would qualitatively identify the organic pollutants in the samples. As a result, a total of 290 organic pollutants were identified, of which 190 and 153 pollutants were found in sediments and sludges, respectively. The identified pollutants included the Environmental Protection Agency (EPA) priority pollutants, pharmaceuticals, herbicides, antioxidants, intermediates, organic solvents and chemical raw materials. The proposed method is proved to be a promising one for non-target screening of complex matrix samples with the advantages of higher sensitivity and better repeatability.

Electrooxidation treatment for removal of emerging pollutants in wastewater sludge

Management of wastewater sludge continues to pose a challenge as its generation is rising as a result of an increase in wastewater treatment and because its quality varies widely. Lately, emerging pollutants have gained importance based on their persistence and potential risk once they enter the environment. Different treatment processes have been proposed to reduce their concentration, such as electrooxidation. Electrooxidation using boron doped diamond electrodes has properties that make them suitable for a wide variety of applications, including wastewater and sludge. Electrooxidation was applied to sludge from a wastewater treatment plant receiving industrial discharges located in Toluca, México. Different pH and current densities were tested at the laboratory and, based on soluble chemical oxygen demand (sCOD) reduction, operating conditions were set at a pH of 3 and a current density of 40mAcm−2 during 1h. Oxidation of organic matter was limited by the concentration of solids during treatment as phased separation (flotation) occurred due to gas generation and additional tests were performed to overcome this situation. 4,4′-(Propane-2,2-diyl)diphenol, Nonylphenol, and 5-chloro-2-(2,4-dichlorophenoxy)phenol were removed by 73%, 89%, and 82% under improved test conditions. Sludge volatile solids were degraded 23% and total COD 27%. Overall, the proposed process represents a promising technology to reduce emerging pollutants in wastewater sludge.

Assessment of pollution level using Mytilus galloprovincialis as a bioindicator species: The case of the Gulf of Trieste

A multidisciplinary approach was used to estimate the pollution level of the marine environment in the North Eastern Adriatic by measurement of the isotopic composition of carbon and nitrogen (δ13C, δ15N), metal/metalloids analyses (Fe, Cu, Zn, As, Se, Cd and Pb, including As speciation) in the Mytilus galloprovincialis, as well by using metallothioneins (MT) concentrations, micronuclei (MN) in gill cells and biological parameters (condition index and gonadosomatic index). Concentrations of MT were in the range from 44 to 175μgg−1 wet matter tissue and were higher at the end of the winter season. The frequency of MN did not indicate an elevated level. Sewage sludge pollution was not confirmed. Elevated As concentrations in mussel are related to salinity and low nutrients concentrations and not to pollution. Elevated concentrations of Cu, Zn and Pb were found in the Bay of Koper in comparison with the Bays of Strunjan and Piran.

DIMENSIONAMENTO DE UM LANDFARMING PARA TRATAMENTO DE BORRAS OLEOSAS UTILIZANDO CRITÉRIOS DE UM REATOR BATELADA

This paper presents a criterion for sizing systems landfarmings, which takes into account the kinetic model of the degradation of pollutants in oily sludge , levels of speeds involved in chemical reactions and adaptation of the theory of batch reactor for the sizing of the ground be installed infrastructure for treatment , since this subject is considered unprecedented in the literature and technical standards that guide the design models of these systems . The methodology used in the development of this work involved the interpretative analysis of texts and pictures present in scientific articles , books , papers and course completion . As analysis of ABNT NBR 13894 1997 for soil treatment (landfarming) . Kinetic data were obtained and considered for kinetic mathematical adjustments first and second order reactions analyzed. The proposed criterion, using the principles of operation of a batch reactor applied to a system Landfarming presented as an acceptable method and consists in advancing the state of the art design methodologies for safe and efficient for this type of system.

Challenge and Development of Sludge Treatment and Disposal in China

As the grim situation of the contamination caused by the sludge is gradually expanded in China, the target to make sludge harmless, stable, reduced, and available is increasingly aimed. Traditional methods and techniques of sludge treatment, disposal, and resource utilization are mature and widely used in many waterworks. With the fast progress of science and technology, some new technologies in treating sludge are appearing to manage the incoming challenge of sludge treatment and disposal. Therefore, the traditional methods and novel development of sludge treatment and disposal are reviewed in this paper in order to find optimal solutions to solve the problems of the sludge pollution.

Priority and emerging pollutants in sewage sludge and fate during sludge treatment

This paper aims at characterizing the quality of different treated sludges from Paris conurbation in terms of micropollutants and assessing their fate during different sludge treatment processes (STP). To achieve this, a large panel of priority and emerging pollutants (n=117) have been monitored in different STPs from Parisian wastewater treatment plants including anaerobic digestion, thermal drying, centrifugation and a sludge cake production unit. Considering the quality of treated sludges, comparable micropollutant patterns are found for the different sludges investigated (in mg/kg DM – dry matter). 35 compounds were detected in treated sludges. Some compounds (metals, organotins, alkylphenols, DEHP) are found in every kinds of sludge while pesticides or VOCs are never detected. Sludge cake is the most contaminated sludge, resulting from concentration phenomenon during different treatments. As regards treatments, both centrifugation and thermal drying have broadly no important impact on sludge contamination for metals and organic compounds, even if a slight removal seems to be possible with thermal drying for several compounds by abiotic transfers. Three different behaviors can be highlighted in anaerobic digestion: (i) no removal (metals), (ii) removal following dry matter (DM) elimination (organotins and NP) and iii) removal higher than DM (alkylphenols – except NP – BDE 209 and DEHP). Thus, this process allows a clear removal of biodegradable micropollutants which could be potentially significantly improved by increasing DM removal through operational parameters modifications (retention time, temperature, pre-treatment, etc.).

Sustainability of Domestic Sewage Sludge Disposal

Activated sludge is now one of the most widely used biological processes for the treatment of wastewaters from medium to large populations. It produces high amounts of sewage sludge that can be managed and perceived in two main ways: as a waste it is discharged in landfill, as a fertilizer it is disposed in agriculture with direct application to soil or subjected to anaerobic digestion and composting. Other solutions, such as incineration or production of concrete, bricks and asphalt play a secondary role in terms of their degree of diffusion. The agronomical value of domestic sewage sludge is a proved question, which may be hidden by the presence of several pollutants such as heavy metals, organic compounds and pathogens. In this way, the sustainability of sewage sludge agricultural disposal requires a value judgment based on knowledge and evaluation of the level of pollution of both sewage sludge and soil. The article analyzed a typical Italian case study, a water management system of small communities, applying the criteria of evaluation of the last official document of European Union about sewage sludge land application, the “Working Document on Sludge (3rd draft, 2000)”. The report brought out good sewage sludge from small wastewater treatment plants and soils quality suggesting a sustainable application.

Phytotreatment of Sewage Sludge Contaminated by Heavy Metals and Pahs by Co-Planting Sedum Alfredii and Alocasia Marorrhiza

High concentrations of heavy metals and organic pollutants in municipal sewage sludge are key factors limiting its use in agriculture. The objectives of this study were to decrease the heavy metal and polycyclic aromatic hydrocarbon concentrations in sewage sludge by phytotreatment and to determine, in a field experiment, whether co-planting is more effective than using a mono-crop of Sedum alfredii. Four treatments were used in the plot experiment: no sludge, no plants, S. alfredii and co-planting S. alfredii and Alocasia marorrhiza. The results showed that co-planting produced tubers and shoots of A. marorrhiza that were suitable as a safe animal feed and good organic K fertilizer, respectively. Co-planting was more effective than mono-planting at reducing concentrations of total Zn and diethylenetriaminepentaacetic acid (DTPA)-extractable Zn, Cd, and Cu in the sludge. Co-planting decreased the concentrations of DTPA-extractable heavy metals and benzo[a]pyrene (B[a]P) in the sludge significantly compared with the unplanted sludge. Decreases of 87, 75, 85, 31, and 64% were obtained for B[a]P and DTPA-extractable Zn, Cd, Cu, and Pb, respectively, compared with the fresh sludge. These results indicate that co-planting can reduce significantly the environmental risks associated with heavy metals and B[a]P in sewage sludge for further disposal.

Characterization of Stainless Steel and Wire Rope Pickling Sludge

With the development of Chinese industry, stainless steel and wire rope pickling sludge pollution problems have become increasingly prominent. Pickling sludge contains a large number of residual acid and heavy metals, and it is hazardous waste which would pose potential environmental problems and threaten people's health if being deposited outdoors or landfill simply. In view of Jiangsu Province present situation of pickling sludge, the paper analyzes the physical properties and the elements content of sludge from 9 enterprises. Pickling sludge pH is basically alkaline and range 7 to 9, moisture content is basically about 50% to 60%. ICP-AES has been applied to identify the content of metals. The range of Fe content is from 13.23% to 35.56% and the range of Ca content is from 1.04% to 29.93%, which shows that pickling sludge is appropriated for resource utilization. Ni and Cr are mainly contained in pickling sludge of stainless steel, the content are 1.79%~3.2% and 2.22%~3.15%, while Pb and Zn are mainly contained in pickling sludge of wire rope, the content are 0.0034%~0.53% and 3.14%~10.18%. The Elemental Analyzer has been applied to determine the content of F, Cl, N, S and P in picking sludge. The paper aims to provide a theoretical basis for making the huge amounts of the sludge harmless and how to utilize the treated sludge.

Life cycle assessment of sewage sludge co-incineration in a coal-based power station

A life cycle assessment was conducted to evaluate the environmental and economic effects of sewage sludge co-incineration in a coal-fired power plant. The general approach employed by a coal-fired power plant was also assessed as control. Sewage sludge co-incineration technology causes greater environmental burden than does coal-based energy production technology because of the additional electricity consumption and wastewater treatment required for the pretreatment of sewage sludge, direct emissions from sludge incineration, and incinerated ash disposal processes. However, sewage sludge co-incineration presents higher economic benefits because of electricity subsidies and the income generating potential of sludge. Environmental assessment results indicate that sewage sludge co-incineration is unsuitable for mitigating the increasing pressure brought on by sewage sludge pollution. Reducing the overall environmental effect of sludge co-incineration power stations necessitates increasing net coal consumption efficiency, incinerated ash reuse rate, dedust system efficiency, and sludge water content rate.