Changes in copper, lead and zinc concentrations in plants from paper mill sludge-treated soils

Effects of paper mill sludge addition on the availability of metals were studied on different soils both laboratory and naturally polluted; copper, lead and zinc concentrations were determined in Hordeum Distichum plants grown on the untreated and on sludge-treated soils. In some case a decrease of metal concentration is observed on sludge-treated soils; these results are consistent with the reduction of metal mobile forms in the soil, before plant growth. The decrease of metal availability in sludge-treated soils may be related with the pH value of the soil after sludge addition.     

Laboratory studies on waste water sludge application for acid soil remediation

In this work the effects of sludge disposal on pH values, buffer capacity and adsorption capacity of an acid soil were studied. A stabilized waste water sludge and a paper mill sludge were employed; the pH values of both sludges were higher than 8. The observed differences between soil-urban sludge and soil-paper mill sludge systems can be ascribed to the nature of the compounds present in the sludges and adsorbed on the soil. Both kinds of sludge are able to modify the natural pH of the soil, the buffer capacity and its capacity to retain metal. These modifications increase with increasing soil-sludge contact time and are higher for paper mill sludges. Temperature affects only the modifications due to urban sludge treatment.     

Morphological and physiological responses of barley plants grown on soils characterised by metal toxicity and metal deficiency

Aim of this work was to investigate which are the effects on barley crops grown on two different soils: a soil lacking in Cu, an essential micronutrient (A) and a naturally polluted soil rich in lead, zinc, copper (B). In particular we investigated the relationship between some ecophysiological parameters such as biomass, chlorophyll concentration and guaiacolo peroxidase activity and the chemical-physical properties of the soils like pH, organic matter and heavy metal content. Because metals uptake by plants is strongly correlated with the bioavailable fraction rather then their total amount in a soil, we have measured also metal exchangeable forms, using a single extraction method (MgCl2 as extractant). Plants grown on soil B showed a metal content higher than background limits, whereas plants grown on soil A were characterised by a background Fe and Zn concentrations and by a tolerant Pb concentration. Conversely, Cu content in tissues of plants grown in soil A is found to be under the background limits. Copper-deficiency plants present chlorotic leaves followed by a reduced clorophyll content, while plants grown on metals contaminated soil showed an increase of peroxidase activity.     

Soil contamination by some organic micropollutants related to sewage sludge spreading

The aim of the present publication is to give some information on soil contamination by 4 different micropollutant classes due to sewage sludge spreading. The soil under research shows an accumulation of light molecular weight PAHs and PCBs, DEHP and 4-NP just after spreading, but one month later the concentration of these micropollutant groups fall to the concentration detected just before the sludge spreading. As far as the soil concentration is concerned, only PAHs and PCBs are precipitation dependent. Some test plots, enriched during 10 years with fertilisers, pig-dung or sewage sludges show only an increase of the PAH concentrations of the plots amended with sludges. In the same way, the sewage sludge is chiefly responsible for the increase of PCBs in the soils, but pig-dung seems to contain quantities of these micropollutants which have to be taken into consideration.     

Soil Contamination by some Organic Micropollutants Related to Sewage Sludge Spreading

Abstract

The aim of the present publication is to give some information on soil contamination by 4 different micropollutant classes due to sewage sludge spreading.

The soil under reserch shown an accumulation of light molecular weight PAHs and PCBs, DEHP and 4-NP just after spreading, but one month later the con-centration of these micropollutant groups fall to the concentration detected just before the sludge spreding.

As far as the soil concentration is concerned, only PAHs and PCBs are precipitation dependent.

Some test plots, enriched during 10 years with fertilisers, pig-dung or sewage sludges show only an increse of the PAH concentrations of the plots amended with sludges. In the same way, the sewage sludge is chiefly responsible for the increase of PCBs in the soils, but pig-dung seems to contain quantities of these micropollutants which have to be taken into consideration.     

Zn adsorption by different fractions of Galician soils

To evaluate the contribution of organic matter, oxides, and clay fraction to Zn adsorption in six soils from Galicia (Spain), after soil characterization, adsorption isotherms were obtained by adding nine solutions containing between 20 and 500 mg L(-1) concentrations of Zn(NO(3))(2). Distribution coefficients were obtained from the data of adsorption isotherms. Zn adsorption isotherms corresponding to untreated soil and to the organic matter removed samples and organic matter and oxides removed samples were compared with curves pattern and adjusted to Langmuir and Freundlich empirical models. Untreated soils described L-curves whereas when soils were deprived of any component, the curves described were S-type. Distribution coefficients allowed knowing the Zn adsorption capacity of the untreated soil, and of the organic matter, oxides, and clay fraction. Soil organic matter is the main component that affects Zn adsorption as long as soil pH is near neutrality. At acid pH, the oxides are the main component that affects Zn adsorption, although to a much smaller extent than the organic matter near neutral conditions. So soil pH is the main soil factor that determines Zn adsorption, before any other soil property.     

Sequestered carbon on clay mineral probed by electron paramagnetic resonance and X-ray photoelectron spectroscopy

This paper describes the interaction among soil organic matter components with kaolinite, an important clay mineral present in tropical soils, especially in Brazil. XPS data show that the soil organic matter adsorbed on kaolinite has aromatic and aliphatic structures, with phenolic and/or alcoholic functions and carbonyl carbons (CO) of amide and/or carboxylic groups. The N1s spectrum of the kaolinite shows an asymmetric peak that is assigned to amide and protonated ammines probably from humin. The interaction between them is strong enough to resist chemical oxidative or reductive attack besides loose amide functionalities. EPR data show that reductive treatment reduces some Fe3+ of the kaolinite structure, loosing organic components. A schematic representation of the reduction of structural Fe3+ in the concentrated domains and consequently increased concentration of Fe3+ ions in diluted domains of the spectrum is presented. This reinforces the hypothesis that humin is a stable carbon sink in soils when adsorbed to clays.     

Determination of molybdenum in extracts of soil and sewage sludge CRMs after fractionation by means of BCR modified sequential extraction procedure

A modified three-step sequential extraction procedure proposed by the Commission of European Communities Bureau of Reference (BCR) was applied to certified reference materials of three different soil groups (rendzina, luvisol, and cambisol) and sewage sludge of different compositions originating from a municipal water treatment plant in order to assess potential mobility and the distribution of molybdenum in the resulting fractions. In the soils examined, molybdenum was present almost entirely in the mineral lattice, the content of molybdenum in the fractions of the studied reference materials of sludges was predominant in the fraction, represents Mo bound to organic matter and sulphide.The internal check of accuracy was performed on the results of the sequential extraction by comparing of the extractable amounts of molybdenum in the sequential procedure with the results of the pseudototal digestion of original samples. The recovery ranged from 96 to 101% and the precision (RSD) in the extracts was below 10%.     

金华市城市污水处理厂污泥成分及农用价值分析

为确定金华市城市污水处理厂污泥资源化利用途径,对金华市某污水处理厂的脱水污泥进行了采样和成分分析.结果表明,所有污泥为中性,pH 6.89,含水率较高75%;污泥中有机质、氮、磷、钾含量丰富;污泥中重金属的含量较低,均符合国家农用污泥中污染物控制标准.以此为基础对污泥的农用价值及其应用前景作了分析和展望.     

Thermodynamic and kinetic study of the single extraction of mercury from soil using sodium-thiosulfate

The use of sodium-thiosulfate (Na-thiosulfate) as a reagent for the extraction of mercury (Hg) from soil was investigated. High organic matter content in soil plays a major role in retaining metals. It has previously been reported that using the cold vapour atomic absorption method, powerful reagents such as EDTA, DTPA and cysteine could not release Hg from soil samples. The optimal conditions for using Na-thiosulfate to extract soil-Hg are presented here. Our results show that 50 ± 5% of total Hg was extracted from soil samples using 0.01 mol L⁻¹ of the reagent without pH adjustment. Increasing the reagent concentration above this level showed no significant change in Hg extraction. From this extraction three fractions of Hg were obtained, the labile, slowly labile and un-extractable. We further applied the use of a kinetic extraction approach that has never been applied for Hg. We observed a correlation between the first two fractions and the quantity of organic matter content in soils. The labile fraction could be released by using any concentration of the reagent. However, the slowly labile fraction was dependent on time and increased concentrations of Na-thiosulfate. Furthermore, our results suggest that the labile and slowly labile fractions involve two different sites of reduced sulphur groups contained in soil organic matter and Hg levels present in the soil samples did not appear high enough to saturate all these high affinity sulphur sites. The capacity of Na-thiosulfate to reduce (Hg(II)) to (Hg(0)), was determined to be negligible. Our results further suggest the implication of iron (Fe(II)) for reducing Hg(II) to Hg(0). Here we have demonstrated that Na-thiosulfate is an effective reagent in the extraction of Hg from soil, with the particular characteristic of its ability to remove strongly bound Hg from sulphur groups contained in soil organic matter.     

Bioconversion of Kraft Paper Mill Sludges to Ethanol by SSF and SSCF

Paper mill sludge is a solid waste material composed of pulp residues and ash generated from pulping and paper making processes. The carbohydrate portion of the sludge has chemical and physical characteristics similar to pulp. Because of its high carbohydrate content and well-dispersed structure, the sludges can be biologically converted to value-added products without pretreatment. In this study, two different types of paper mill sludges, primary sludge and recycle sludge, were evaluated as a feedstock for bioconversion to ethanol. The sludges were first subjected to enzymatic conversion to sugars by commercial cellulase enzymes. The enzymatic conversion was inefficient because of interference by ash in the sludges with the enzymatic reaction. The main cause was that the pH level is dictated by CaCO₃ in ash, which is two units higher than the pH optimum of cellulase. To alleviate this problem, simultaneous saccharification and cofermentation (SSCF) using cellulase (Spezyme CP) and recombinant Escherichia coli (ATCC-55124), and simultaneous saccharification and fermentation (SSF) using cellulase and Saccharomyces cerevisiae (ATCC-200062) were applied to the sludges without any pretreatment. Ethanol yields of 75–81% of the theoretical maximum were obtained from the SSCF on the basis of total carbohydrates. The yield from the SSF was also found to be in the range of 74–80% on the basis of glucan. The SSCF and SSF proceeded under stable condition with the pH staying near 5.0, close to the optimum for cellulase. Decrease of pH occurred due to carbonic acid and other organic acids formed during fermentation. The ash was partially neutralized by the acids produced from the SSCF and SSF and acted as a buffer to stabilize the pH during fermentation. When the SSF and SSCF were operated in fed-batch mode, the ethanol concentration in the broth increased from 25.5 and 32.6 g/L (single feed) to 45 and 42 g/L, respectively. The ethanol concentration was limited by the tolerance of the microorganism in the case of SSCF. The ethanol yield in fed-batch operation decreased to 68% for SSCF and 70% for SSF. The high-solids condition in the bioreactor appears to create adverse effects on the cellulase reaction.     

Characterization and pyrolysis behaviour of different paper mill waste materials

Paper industry generates a considerable amount of wastes. Their composition mainly depends on the type of paper produced and the origin of cellulose fibres. Nowadays, in Spain, 40% of solid wastes generated by the paper and pulp industry are deposited directly in landfill, 25% are used in the agriculture, 13% in the ceramic industry and 7% in the concrete production. In the last years, thermal treatment methods like combustion, pyrolysis and gasification have been widely study as alternative techniques for the valorization of different organic waste materials. The main objective of the present work is to study the pyrolysis behaviour of different paper mill waste materials. For this reason, a wide characterization of eight paper mill waste materials from different origins was performed using SEM, FTIR, DRX and thermogravimetric techniques. Paper mill sludges from recycled paper, mainly wastes obtained from deinking process, showed high CaCO₃ and clays contents. Compared with the elevated total organic matter content (TOM) of paper mill waste materials their low organic carbon content determined by Cr₂O₇²⁻ oxidation reveals the elevated chemical stability of organic matter, due to high content on cellulose fibres. Analysis of samples by SEM indicates that successive recycled processes of paper leads to paper mill waste materials with more degraded fibres. XRD analyses show as crystalline cellulose was present in reject and primary sludge from paper mills that produced paper from virgin wood. However, crystalline cellulose content significantly decreased in waste materials from recycled paper. Finally, thermogravimetric analysis indicates that presence or mineral matter and degradation of cellulose significantly influences their pyrolysis behaviour. In general, weight loss of paper mill waste materials started at lower temperatures than pure cellulose. In waste materials from recycled paper weight loss continues at temperatures highest than 500 °C due to kaolinite dehydration and carbonates decomposition.     

Retention of Metamitron by Model and Natural Particulate Matter

Abstract

Adsorption isotherms of metamitron on model soil colloidal components: kaolinite, illite, montmorillonite, iron oxide and humic acid, and their binary associations were obtained using a batch equilibration procedure. Sorption parameters, K_f and n_f, were calculated by fitting the sorption data to the Freundlich equation and results obtained for binary associations were compared with those obtained for the individual model components. The sorption efficiency of the humic acids and their binary associations was measured as Koc. The adsorption behaviour of the < 2 μm fraction of two soils from Southern Spain was also studied as natural particulate matter. Montmorillonite and humic acids were found to be the most important components responsible for metamitron retention by the model adsorbents studied. On the contrary, metamitron showed little interaction with kaolinite, illite or iron oxide. These individual adsorption behaviours were reproduced in the montmorillonite-iron oxide-humic acid binary systems, but with differences suggesting changes on the surface properties upon association. Differences in Koc values of isolated humic acids and their associations indicate that the interaction transforms the humic acid surfaces and suggest different types of bonding between colloids and metamitron. The results obtained with model adsorbents and their associations were in agreement with the highest adsorption of metamitron found for the natural clay fraction of two soils which displayed the largest adsorption in that with the highest content in montmorillonite and organic carbon. The importance of organic matter and montmorillonite in metamitron adsorption by colloidal components was also shown by the decrease in K_f and the increase in Koc observed after removal of organic matter from the soil clay fraction with the highest organic carbon content.     

造纸污泥添加剂对麦秆灰烧结熔融特性的影响

利用灰熔点测试仪、XRD及XRF等仪器,对比研究了造纸污泥(脱墨污泥、造纸废水污泥)、城市废水污泥作为添加剂对麦秆灰熔融特性的影响,考察了烧结和熔融过程中的组分变化,分析了污泥添加剂对麦秆灰的作用机理;进一步将污泥添加剂与常规添加剂进行灰熔融特性对比研究。研究发现,添加比例控制为3%-10%,造纸污泥(脱墨污泥、造纸废水污泥)软化温度提升效果均优于城市废水污泥;在添加比例控制为5%时,造纸废水污泥对麦秆灰软化温度提升效果最好;增大添加比例过程中,造纸废水污泥Al_2O_3修饰骨架作用明显,但灰中长石类物质逐渐增多使得软化温度提升效果下降;在不同温度下,脱墨污泥主要是通过形成硅铝榴石使得灰熔点提升,造纸废水污泥则主要是通过生成高熔点物质CaSiO_3抑制低熔点硅酸盐形成,城市废水污泥升温中存在明显SiO_2晶态转变过程;使用污泥添加剂作为抗结渣添加剂具有良好应用前景。     

Paper mill sludge-soil mixture: kinetic and thermodynamic tests of cadmium and lead sorption capability

Paper mill sludge (characterized by 29.0% of organic substances such as cellulose, lignin and tannins and 71.0% of inorganic substances such as kaolinite and carbonates) was studied in a mixture with soil in order to evaluate its effects on soil capability for retaining heavy metals. Attention was focused on cadmium and lead sorption and two parameters were investigated, the contact time of paper mill sludge-soil mixture and the paper mill sludge-soil ratio in the mixture. Results showed that paper mill sludge and soil interact to form ‘new’ sorbing sites. Taking into account sorption results of lead, the retention of which by soil is substantially increased by sludge addition, can highlight this modification. Also, the amount of sorbed cadmium was increased by sludge addition.     

Agricultural valorisation of de-inking paper sludge as organic amendment in different soils

The objective of this study is to study the influence of de-inking paper sludge (DPS) and sewage sludge (SL) mixtures addition at different rates (2, 4 and 8%) in two soils. Incubation experiments were performed during 60 days and the influence of treatments in physical soil properties was determined by soil porosity and stability of aggregates. Differential thermal analysis (DTA) of amended soils after incubation was performed. Experimental results show that amendment increased biological soil activity, soil porosity and stability of aggregates. DTA analysis shows that the first exothermic peak generally increases with the dosage of DPS:SL due to the addition of immature organic matter. Moreover, the second peak enlarges probably due to the humification process during incubation.     

Speciation of heavy metals in sewage sludge after mesophilic and thermophilic anaerobic digestion

Two types of sewage sludge anaerobic digestion were carried out: mesophilic and thermophilic. Metal speciation analysis was performed revealing some changes in the chemical form of the metals during the stabilization process of sludge. After both methane fermentation processes, a comparable level of organic matter distribution was obtained (≈ 40 %). The amount of produced methane during thermophilic and mesophilic digestion was 560 mL of CH4 and 580 mL of CH₄ from 1 g of removed organic matter, respectively. Low concentration of heavy metal ions in the liquid phase of sludge was observed. Metal ions precipitated and remained bound throughout the stabilization process. No accumulation of heavy metals in the mobile fractions of sludge (exchangeable and carbonate) was observed for either digestion process. The highest increase of zinc, copper, nickel, cadmium, and chromium concentration was observed in the organic-sulfide fraction, whereas the highest increase of lead was found in the residual fraction.     

Potassium hexacyanoruthenate(II) as an analytical reagent for iron

Fe(III) undergoes a reaction with colourless Ru(CN)(4-)(6) to produce an intensely violet-blue complex that absorbs at 550 nm and obeys Beer's law over the iron concentration range 0.04-2 mug/ml in acidic medium. Some common cations and anions are tolerable at low concentrations. The procedure is applicable for determination of total iron in potable water. Destruction of organic matter is required for contaminated surface waters or soil samples.     

土壤有机氯脱氯转化的界面交互反应*

有机氯杀虫剂、除草剂等难降解有机物是重要的土壤污染物。近年来,有机氯脱氯转化的界面过程已成为土壤环境科学的研究热点。本文综述了土壤有机氯脱氯转化的界面非生物过程、界面生物过程以及界面生物－非生物交互反应过程。界面脱氯转化过程与主要土壤化学过程、土壤根际过程相互关联,该过程中,铁物种循环与铁氧化物的异化还原溶解扮演了重要角色。     

Production of Cellulase from Kraft Paper Mill Sludge by Trichoderma Reesei Rut C-30

Paper mill sludge is a solid waste material generated from pulping and papermaking operations. Because of high glucan content and its well-dispersed structure, paper mill sludges are well suited for bioconversion into value-added products. It also has high ash content originated from inorganic additives used in papermaking, which causes hindrance to bioconversion. In this study, paper mill sludges from Kraft process were de-ashed by a centrifugal cleaner and successive treatment by sulfuric acid and sodium hydroxide, and used as a substrate for cellulase production. The treated sludge was the only carbon source for cellulase production, and predominantly inorganic nutrients were used as the nitrogen source for this bioprocess. The cellulase enzyme produced from the de-ashed sludge exhibited cellulase activity of 8 filter paper unit (FPU)/mL, close to that obtainable from pure cellulosic substrates. The yield of cellulase enzyme was 307 FPU/g glucan of de-ashed sludge. Specific activity was 8.0 FPU/mg protein. In activity tests conducted against the corn stover and α-cellulose, the xylanse activity was found to be higher than that of a commercial cellulase. Relatively high xylan content in the sludge appears to have induced high xylanase production. Simultaneous saccharification and fermentation (SSF) was performed using partially de-ashed sludge as the feedstock for ethanol production using Sacharomyces cerevisiae and the cellulase produced in-house from the sludge. With 6% (w/v) glucan feed, ethanol yield of 72% of theoretical maximum and 24.4 g/L ethanol concentration were achieved. These results were identical to those of the SSF using commercial cellulases.