Black water sludge reuse in agriculture: Are heavy metals a problem?
Tervahauta, T.H. ; Rani, S. ; Leal, L.H. ; Buisman, C.J.N. ; Zeeman, G. - \ 2014
Journal of Hazardous Materials 274 (2014). - ISSN 0304-3894 - p. 229 - 236.
soil carbon sequestration - mitigate climate-change - urban waste-water - uk total diet - sewage-sludge - trace-elements - lactovegetarian diet - european countries - human physiology - human exposure
Heavy metal content of sewage sludge is currently the most significant factor limiting its reuse in agriculture within the European Union. In the Netherlands most of the produced sewage sludge is incinerated, mineralizing the organic carbon into the atmosphere rather than returning it back to the soil. Source-separation of black water (toilet water) excludes external heavy metal inputs, such as industrial effluents and surface run-offs, producing sludge with reduced heavy metal content that is a more favorable source for resource recovery. The results presented in this paper show that feces is the main contributor to the heavy metal loading of vacuum collected black water (52-84%), while in sewage the contribution of feces is less than 10%. To distinguish black water from sewage in the sludge reuse regulation, a control parameter should be implemented, such as the Hg and Pb content that is significantly higher in sewage sludge compared to black water sludge (from 50- to 200-fold). The heavy metals in feces and urine are primarily from dietary sources, and promotion of the soil application of black water sludge over livestock manure and artificial fertilizers could further reduce the heavy metal content in the soil/food cycle. (C) 2014 Elsevier B.V. All rights reserved.
The increasing impact of food production on nutrient export by rivers to the Bay of Bengal 1970–2050
Sattar, M.A. ; Kroeze, C. ; Strokal, M. - \ 2014
Marine Pollution Bulletin 80 (2014)1-2. - ISSN 0025-326X - p. 168 - 178.
harmful algal blooms - management strategies - coastal nitrogen - shrimp culture - future-trends - sewage-sludge - water-quality - india - soil - eutrophication
The objective of this study is to assess the impact of food production on river export of nutrients to the coastal waters of the Bay of Bengal in the past (1970 and 2000) and the future (2030 and 2050), and the associated potential for coastal eutrophication. We model nutrient export from land to sea, using the Global NEWS (Nutrient Export from WaterSheds) approach. We calculate increases in river export of N and P over time. Agricultural sources account for about 70–80% of the N and P in rivers. The coastal eutrophication potential is high in the Bay. In 2000, nutrient discharge from about 85% of the basin area of the Bay drains into coastal seas contributes to the risk of coastal eutrophication. By 2050, this may be 96%. We also present an alternative scenario in which N and P inputs to the Bay are 20–35% lower than in the baseline.
Nitrous Oxide (N2O) emissions from human waste in 1970-2050
Strokal, M. ; Kroeze, C. - \ 2014
Current Opinion in Environmental Sustainability 9-10 (2014). - ISSN 1877-3435 - p. 108 - 121.
water treatment-plant - coastal waters - climate-change - future-trends - sewage-sludge - anthropogenic nitrogen - reactive nitrogen - nutrient export - surface-water - united-states
Nitrous oxide (N2O) is an important contributor to climate change. Human waste is an important source of N2O emissions in several world regions, and its share in global emissions may increase in the future. In this paper we, therefore, address N2O emission from human waste: collected (from treatment and from sewage discharges) and uncollected waste. We review existing literature on emissions and emission factors, and present region-specific estimates of N2O emissions and their past and future trends. We show that human waste may became an important source of N2O emissions in the coming years as a result of increasing urbanization. About two-thirds of the global emissions are from uncollected waste, and about half from South Asia. We argue that more research is needed to improve emission factors.
Improved Energy Recovery by Anaerobic Grey Water Sludge Treatment with Black Water
Tervahauta, T.H. ; Bryant, I.M. ; Hernandez Leal, L. ; Buisman, C.J.N. ; Zeeman, G. - \ 2014
Water 6 (2014)8. - ISSN 2073-4441 - p. 2436 - 2448.
municipal solid-wastes - grease trap sludge - co-digestion - sewage-sludge - decentralized sanitation - biogas production - uasb reactor - systems - reuse
This study presents the potential of combining anaerobic grey water sludge treatment with black water in an up-flow anaerobic sludge blanket (UASB) reactor to improve energy recovery within source-separated sanitation concepts. Black water and the mixture of black water and grey water sludge were compared in terms of biochemical methane potential (BMP), UASB reactor performance, chemical oxygen demand (COD) mass balance and methanization. Grey water sludge treatment with black water increased the energy recovery by 23% in the UASB reactor compared to black water treatment. The increase in the energy recovery can cover the increased heat demand of the UASB reactor and the electricity demand of the grey water bioflocculation system with a surplus of 0.7 kWh/cap/y electricity and 14 MJ/cap/y heat. However, grey water sludge introduced more heavy metals in the excess sludge of the UASB reactor and might therefore hinder its soil application.
Impacts of climate change on the microbial safety of pre-harvest leafy green vegetables as indicated by Escherichia coli O157 and Salmonella spp.
Liu, C. ; Hofstra, N. ; Franz, E. - \ 2013
International Journal of Food Microbiology 163 (2013)2-3. - ISSN 0168-1605 - p. 119 - 128.
enterica serovar typhimurium - manure-amended soil - irrigation water - united-states - fresh produce - multistate outbreak - sewage-sludge - pathogenic microorganisms - contaminated manure - ambient-temperature
The likelihood of leafy green vegetable (LGV) contamination and the associated pathogen growth and survival are strongly related to climatic conditions. Particularly temperature increase and precipitation pattern changes have a close relationship not only with the fate and transport of enteric bacteria, but also with their growth and survival. Using all relevant literature, this study reviews and synthesises major impacts of climate change (temperature increases and precipitation pattern changes) on contamination sources (manure, soil, surface water, sewage and wildlife) and pathways of foodborne pathogens (focussing on Escherichia coli O157 and Salmonella spp.) on pre-harvested LGVs. Whether climate change increases their prevalence depends not only on the resulting local balance of the positive and negative impacts but also on the selected regional climate change scenarios. However, the contamination risks are likely to increase. This review shows the need for quantitative modelling approaches with scenario analyses and additional laboratory experiments. This study gives an extensive overview of the impacts of climate change on the contamination of pre-harvested LGVs and shows that climate change should not be ignored in food safety management and research.
Environmental Selenium Research: From Microscopic Processes to Global Understanding
Winkel, L.H.E. ; Johnson, C.A. ; Lenz, M. ; Grundl, T. ; Leupin, O.X. ; Amini, M. ; Charlet, L. - \ 2012
Environmental Science and Technology 46 (2012)2. - ISSN 0013-936X - p. 571 - 579.
plasma-mass spectrometry - icp-ms - arsenic contamination - agricultural soils - sewage-sludge - speciation - se - chromatography - groundwater - metabolism
Selenium is a natural trace element that is of fundamental importance to human health. The extreme geographical variation in selenium concentrations in soils and food crops has resulted in significant health problems related to deficient or excess levels of selenium in the environment. To deal with these kinds of problems in the future it is essential to get a better understanding of the processes that control the global distribution of selenium. The recent development of analytical techniques and methods enables accurate selenium measurements of environmental concentrations, which will lead to a better understanding of biogeochemical processes. This improved understanding may enable us to predict the distribution of selenium in areas where this is currently unknown. These predictions are essential to prevent future Se health hazards in a world that is increasingly affected by human activities.
Degradation of 4-n-nonylphenol under nitrate reducing conditions
Weert, J.P.A. de; Vinas, M. ; Grotenhuis, J.T.C. ; Rijnaarts, H.H.M. ; Langenhoff, A.A.M. - \ 2011
Biodegradation 22 (2011)1. - ISSN 0923-9820 - p. 175 - 187.
anaerobic degradation - desulfobacterium-phenolicum - polychlorinated-biphenyls - nonionic surfactants - sewage-sludge - n-hexadecane - sp-nov - nonylphenol - biodegradation - 4-nonylphenol
Nonylphenol (NP) is an endocrine disruptor present as a pollutant in river sediment. Biodegradation of NP can reduce its toxicological risk. As sediments are mainly anaerobic, degradation of linear (4-n-NP) and branched nonylphenol (tNP) was studied under methanogenic, sulphate reducing and denitrifying conditions in NP polluted river sediment. Anaerobic bioconversion was observed only for linear NP under denitrifying conditions. The microbial population involved herein was further studied by enrichment and molecular characterization. The largest change in diversity was observed between the enrichments of the third and fourth generation, and further enrichment did not affect the diversity. This implies that different microorganisms are involved in the degradation of 4-n-NP in the sediment. The major degrading bacteria were most closely related to denitrifying hexadecane degraders and linear alkyl benzene sulphonate (LAS) degraders. The molecular structures of alkanes and LAS are similar to the linear chain of 4-n-NP, this might indicate that the biodegradation of linear NP under denitrifying conditions starts at the nonyl chain. Initiation of anaerobic NP degradation was further tested using phenol as a structure analogue. Phenol was chosen instead of an aliphatic analogue, because phenol is the common structure present in all NP isomers while the structure of the aliphatic chain differs per isomer. Phenol was degraded in all cases, but did not affect the linear NP degradation under denitrifying conditions and did not initiate the degradation of tNP and linear NP under the other tested conditions.
Residues of bioenergy production chains as soil amendments: Immediate and temporal phytotoxicity
Gell, K. ; Groenigen, J.W. van; Cayuela, M.L. - \ 2011
Journal of Hazardous Materials 186 (2011)2-3. - ISSN 0304-3894 - p. 2017 - 2025.
seed-germination - risk-assessment - rapeseed meal - sewage-sludge - by-products - paper-mill - bio-oil - biochar - growth - pyrolysis
The current shift towards bioenergy production increases streams of bioenergy rest-products (RPs), which are likely to end-up as soil amendments. However, their impact on soil remains unclear. In this study we evaluated crop phytotoxicity of 15 RPs from common bioenergy chains (biogas, biodiesel, bioethanol and pyrolysis). The RPs were mixed into a sandy soil and the seedling root and shoot elongation of lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), and wheat (Triticum aestivum L.) were measured. Immediate phytotoxic effects were observed with biodiesel and bioethanol RPs (root elongation reduced to 14-60% for the three crops; P
Accumulation of background levels of persistent organochlorine and organobromine pollutants through the soil-earthworm-hedgehog food chain
Vermeulen, F. ; Covaci, A. ; Havé, H. D'; Brink, N.W. van den; Blust, R. ; Coen, W. De; Bervoets, L. - \ 2010
Environment International 36 (2010)7. - ISSN 0160-4120 - p. 721 - 727.
brominated flame retardants - polybrominated diphenyl ethers - pollution exposure assessment - polychlorinated-biphenyls - erinaceus-europaeus - risk-assessment - aromatic-hydrocarbons - organic pollutants - sewage-sludge - hair
The bioaccumulation of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and DDT and metabolites, was investigated in the soil–earthworm–hedgehog food chain. Concentrations of selected POPs were measured in soil and earthworms collected in grassland and open woodland and in hair and blood of hedgehogs foraging in two parks containing these habitats. Despite background concentrations in soil (ranging from 1.3 to 9.3 ng/g for DDTs, 2.3 to 6.5 ng/g for PCBs and 0.08 to 0.20 ng/g for PBDEs), biota-soil accumulation factors (BSAFs) indicated that earthworms accumulated POPs (0.48–1.70 for DDTs, 1.09–2.76 for PCBs and 1.99–5.67 for PBDEs) and that animals feeding on earthworms are potentially exposed to higher concentrations of pollutants. BSAFs decreased with increasing soil concentrations for the three groups of compounds, suggesting that steady-state equilibrium was not reached in soil or earthworms. Positive, but low, log-linear relationships were found for DDT (r2 = 0.23, p <0.05 for Brasschaat and r2 = 0.63, p <0.01 for Hoboken) and PCB (r2 = 0.13, p <0.05 for both parks) concentrations between soil and earthworms. In order to relate earthworm to hedgehog POP concentrations, the foraging behavior of each individual was taken into account. The use of hair as a potential biomonitoring tissue in exposure and risk assessment of POPs was evaluated by examining the relationship between PCB and p,p'-DDE levels in hedgehogs' hair and blood. Contaminant profiles were used to gain insight into biotransformation of the studied compounds in each step of the investigated food chain and in the blood of hedgehogs, as well as the consequences thereof for their incorporation in hair. The absence of a discernable relationship between POP concentrations in earthworms and hair is possible due to variation in individual foraging behavior and POP uptake. Our results suggest that POPs in tissues should be measured from an adequate number of individuals per population instead of relying on indirect estimates from levels in soil or prey items.
Aerobic nonylphenol degradation and nitro-nonylphenol formation by microbial cultures from sediments
Weert, J.P.A. de; Viñas, M. ; Grotenhuis, J.T.C. ; Rijnaarts, H.H.M. ; Langenhoff, A.A.M. - \ 2010
Applied Microbiology and Biotechnology 86 (2010)2. - ISSN 0175-7598 - p. 761 - 771.
sphingomonas-xenophaga bayram - sp strain ttnp3 - river sediment - nitrosomonas-europaea - ipso-substitution - p-nonylphenol - sewage-sludge - bisphenol-a - 4-nonylphenol - biodegradation
Nonylphenol (NP) is an estrogenic pollutant which is widely present in the aquatic environment. Biodegradation of NP can reduce the toxicological risk. In this study, aerobic biodegradation of NP in river sediment was investigated. The sediment used for the microcosm experiments was aged polluted with NP. The biodegradation of NP in the sediment occurred within 8 days with a lag phase of 2 days at 30°C. During the biodegradation, nitro-nonylphenol metabolites were formed, which were further degraded to unknown compounds. The attached nitro-group originated from the ammonium in the medium. Five subsequent transfers were performed from original sediment and yielded a final stable population. In this NP-degrading culture, the microorganisms possibly involved in the biotransformation of NP to nitro-nonylphenol were related to ammonium-oxidizing bacteria. Besides the degradation of NP via nitro-nonylphenol, bacteria related to phenol-degrading species, which degrade phenol via ring cleavage, are abundantly present
Aquatic worms grown on biosolids: Biomass composition and potential applications
Elissen, H.J.H. ; Mulder, W.J. ; Hendrickx, T.L.G. ; Elbersen, H.W. ; Beelen, M.J.C. ; Temmink, B.G. ; Buisman, C.J.N. - \ 2010
Bioresource Technology 101 (2010)2. - ISSN 0960-8524 - p. 804 - 811.
lumbriculus-variegatus oligochaeta - biodiesel production - sewage-sludge - earthworms - bioaccumulation - toxicity - sediment - cadmium - lipids - diet
The increasing production of biological waste sludge from wastewater treatment plants is a problem, because stricter legislation inhibits the use of traditional disposal methods. The use of the aquatic worm Lumbriculus variegatus can minimise sludge production. Because the worms can feed and grow on this waste sludge, valuable compounds that are present in the sludge can be recovered by the worms. This paper describes a systematic approach for finding possible applications of the produced biomass. The worm biomass mainly consists of protein and smaller fractions of fat, sugar and ash. It also contains low concentrations of heavy metals. The potential produced amount is relatively small, compared to other waste streams, and is produced decentrally. Therefore, the most promising applications are specific components of the biomass, for example specific amino acids or fatty acids. However, until the process is optimized and there is a stable supply of worms, the focus should be on simple applications, later on followed by specific applications, depending on the market demand. Worm biomass grown on clean sludges has a broader application potential, for example as consumption fish feed.
Effects of physico-chemical factors on the viscosity evolution of anaerobic granular sludge
Pevere, A. ; Guibaud, G. ; Goin, E. ; Hullebusch, E.D. van; Lens, P.N.L. - \ 2009
Biochemical Engineering Journal 43 (2009)3. - ISSN 1369-703X - p. 231 - 238.
activated-sludge - waste-water - rheological parameters - sewage-sludge - reactor - suspensions - extraction - cobalt - flocs
The rheological properties of anaerobic granular Sludge samples from four full-scale and one lab-scale anaerobic bioreactors were characterized by determining their "limit viscosity" values. These values were deducted from the evolution of the apparent viscosity of granular sludge samples (20 mL) at steady shear rate (200s(-1)) recorded using rotation tests with a wings type measurement cell stirrer Anton-Parr reference: ST24-1D/2V-Q0. The limit viscosity values depended on the applied shear rate, indicating a non-Newtonian behavior of the anaerobic granular sludge types investigated. The effect of variations of physico-chemical parameters such as pH (involving surface charge change), size, surface roughness and TSS content on the evolution of the limit viscosity of an anaerobic granular sludge suspension was investigated. This showed the importance of both quantitative (number of particles in a given volume) as well as qualitative (surface charge or shape) granule-granule interactions on this theological parameter. Moreover, the origin of the granular sludge strongly influenced the limit viscosity value according with different granules characteristics. This work confirms the ability of the rheological parameter "limit viscosity" as an overall parameter to describe the physico-chemical characteristics (TSS, granulometry, origin, and charge) of anaerobic granular Sludge and showed this holds for both sieved (500 mu m) and unsieved sludges.
Heavy metals and soil microbes
Giller, K.E. ; Witter, E. ; McGrath, S. - \ 2009
Soil Biology and Biochemistry 41 (2009)10. - ISSN 0038-0717 - p. 2031 - 2037.
leguminosarum-biovar-trifolii - biotic ligand model - term field experiment - sewage-sludge - contaminated soils - agricultural soils - nitrogen-fixation - past applications - zinc concentrations - copper toxicity
The discovery in the early 1980s that soil microorganisms, and in particular the symbiotic bacteria Rhizobium, were highly sensitive to heavy metals initiated a new line of research. This has given us important insights into a range of topics: ecotoxicology, bioavailability of heavy metals, the role of soil biodiversity, and the existence of ‘keystone’ organisms. Concurrently, and particularly in Europe, the research led to new approaches to the protection of soils from pollution that take into account the many effects on soil microorganisms. To date these key findings have largely been ignored in the USA, although our results caused considerable controversy there. In the past decade there have been many advances in the ecotoxicological assessment of metals and their effects on soil organisms but major gaps in knowledge and theory remain with regard to how microorganisms are exposed and respond to metals in soils. In this brief review we emphasise the need for long-term experiments and basic research to forge this understanding and improve environmental protection policies.
Predicting the phytoextraction duration to remediate heavy metal contaminated soils
Koopmans, G.F. ; Römkens, P.F.A.M. ; Song, J. ; Temminghoff, E.J.M. ; Japenga, J. - \ 2007
Water Air and Soil Pollution 181 (2007)1-4. - ISSN 0049-6979 - p. 355 - 371.
hyperaccumulator thlaspi-caerulescens - organic-matter - lead phytoextraction - accumulating plants - sewage-sludge - phytoremediation - cadmium - ph - phosphate - zinc
The applicability of phytoextraction to remediate soils contaminated with heavy metals (HMs) depends on, amongst others, the duration before remediation is completed. The impact of changes in the HM content in soil occurring during remediation on plant uptake has to be considered in order to obtain a reliable estimate of the phytoextraction duration. To simulate the decrease in the HM content in soil and to assess the resulting decrease in the uptake of HMs by plants, contaminated soil was mixed with uncontaminated, but otherwise similar soil. Uptake of Cd, Pb, and Zn by the indicator plant Lupinus hartwegii and the Zn hyperaccumulator Thlaspi caerulescens (La Calamine ecotype) was a log-linear function of the in-situ measured HM soil solution concentrations. Over a wide range in dissolved Cd and Zn concentrations, uptake of these HMs by T. caerulescens was (much) greater than by L. hartwegii. Experimentally derived regression models describing the relationships between soil, soil solution, and plant were implemented in a HM mass balance model used to obtain estimates of the phytoextraction duration. For our target soils, estimates of the Cd phytoextraction duration using L. hartwegii or T. caerulescens increased significantly by more than 100 or 50 years when experimental soil¿soil solution¿plant relationships were used instead of the assumption of constant plant uptake of Cd. The two approaches gave similar results for phytoextraction of Zn by T. caerulescens.
Transfer and loss of naturally-occuring plasmids among isolates of Rhizobium leguminosarum bv. viciae in heavy metal contaminated soils
Lakzian, A. ; Murphy, P.J. ; Giller, K.E. - \ 2007
Soil Biology and Biochemistry 39 (2007)5. - ISSN 0038-0717 - p. 1066 - 1077.
sewage-sludge - nitrogen-fixation - biovar trifolii - past applications - host-plant - survival - identification - populations - environment - resistance
Plasmid transfer among isolates of Rhizobium leguminosarum bv. viciae in heavy metal contaminated soils from a long-term experiment in Braunschweig, Germany, was investigated under laboratory conditions. Three replicate samples each of four sterilized soils with total Zn contents of 54, 104, 208 and 340 mg kg¿1 were inoculated with an equal number (1×105 cells g¿1 soil) of seven different, well-characterized isolates of R. leguminosarum bv. viciae. Four of the isolates were from an uncontaminated control plot (total Zn 54 mg kg¿1) and three were from a metal-contaminated plot (total Zn 340 mg kg¿1). After 1 year the population size was between 106 and 107 g¿1 soil, and remained at this level in all but the most contaminated soil. In the soil from the most contaminated plot no initial increase in rhizobial numbers was seen, and the population declined after 1 year to
Nematodes as sentinels of heavy metals and organic toxicants in the soil
Ekschmitt, K. ; Korthals, G.W. - \ 2006
Journal of Nematology 38 (2006)1. - ISSN 0022-300X - p. 13 - 19.
caenorhabditis-elegans - sewage-sludge - communities - copper - cadmium - invertebrate - glutathione - pollution - toxicity - stress
Field and laboratory research has repeatedly shown that free-living soil nematodes differ in their sensitivity to soil pollution. In this paper, we analyze whether nematode genera proved sensitive or tolerant toward heavy metals and organic pollutants in six long-term field experiments. We discuss overlaps between nematode physiological responses to heavy metals and to organic pollutants, which may explain why nematodes can exhibit co-tolerance toward several contaminants. We propose a simple method for separating direct effects of soil contamination on nematode populations from indirect effects mediated through the food chain. Finally, we analyze the extent to which nematodes exhibited consistent responses across the experiments analyzed. Our results show that (a) indirect effects of pollution were generally strong; (b) fewer nematode genera were tolerant than sensitive; (c) many genera, including practically all Adenophorea, exhibited a common response pattern to contaminants; and (d) several genera of the Secernentea exhibited differential tolerance toward particular pollutants. We conclude that bioindication of soil contamination should preferentially be based on tolerant, and less on sensitive, nematodes. We provide a list of nematode genera that may potentially serve as differential bioindicators for specific soil contaminants.
Electrokinetic copper and iron migration in anaerobic granular sludge
Virkutyte, J. ; Sillanpää, M.J. ; Lens, P.N.L. - \ 2006
Water Air and Soil Pollution 177 (2006)1-4. - ISSN 0049-6979 - p. 147 - 168.
treated wood waste - heavy-metals - electrodialytic remediation - sewage-sludge - pilot-scale - removal - soils - extraction - water - chromium
The application of low-level direct electric current (0.15 mA cm¿2) as an electrokinetic technique to treat copper-contaminated mesophilic anaerobic granular sludge was investigated. The sludge was obtained from a full scale UASB reactor treating paper-mill wastewater and was artificially contaminated by Cu(NO3)2 or CuEDTA2¿ with initial copper concentrations of 1000 mg . kg¿1 wet sludge. The effect of different electrokinetic cell layouts, pH and EDTA concentrations on the migration of copper and iron during electrokinetic treatment were evaluated. Both, the pH of the sludge cake or the copper complexation with EDTA significantly affected the migration direction of copper. In an `open¿ cell (sludge cake in direct contact with air), the highest copper mobility was observed at pH 2.5 in both Cu(NO3)2 or CuEDTA2¿ amended sludge. The highest copper accumulation was at the cathode (22 ± 2)% with CuEDTA2¿ as contaminant. In a `closed¿ cell (sludge cake not in contact with air), the highest accumulation was obtained for CuEDTA2¿ at the anode and amounted to 4(± 0.5)% and 2(± 0.05)%, respectively, at a final pH of 4.2 and 7.7 in the sludge cake
Copper and trace element fractionation in electrokinetically treated methanogenic anaerobic granular sludge
Virkutyte, J. ; Hullebusch, E.D. van; Sillanpaa, M. ; Lens, P.N.L. - \ 2005
Environmental Pollution 138 (2005)3. - ISSN 0269-7491 - p. 517 - 529.
metal-contaminated soils - heavy-metals - sewage-sludge - sequential extraction - pilot-scale - removal - remediation - speciation - zinc - sediments
The effect of electrokinetic treatment (0.15 mA cm(-2)) on the metal fractionation in anaerobic granular sludge artificially contaminated with copper (initial copper concentration 1000 mg kg(-1) wet sludge) was studied. Acidification of the sludge (final pH 4.2 in the sludge bed) with the intention to desorb the copper species bound to the organic/sulfides and residual fractions did not result in an increased mobility, despite the fact that a higher quantity of copper was measured in the more mobile (i.e. exchangeable/carbonate) fractions at final pH 4.2 compared to circum-neutral pH conditions. Also addition of the chelating agent EDTA (Cu2+:EDTA4- ratio 1.2:1) did not enhance the mobility of copper from the organic/sulfides and residual fractions, despite the fact that it induced a reduction of the total copper content of the sludge. The presence of sulfide precipitates likely influences the copper mobilisation from these less mobile fractions, and thus makes EDTA addition ineffective to solubilise copper from the granules
The effect of long-term irrigation using wastewater on heavy metal contents of soils under vegetables in Harare, Zimbabwe
Mapanda, F. ; Mangwayana, E.N. ; Nyamangara, J. ; Giller, K.E. - \ 2005
Agriculture, Ecosystems and Environment 107 (2005)2-3. - ISSN 0167-8809 - p. 151 - 165.
sewage-sludge - effluent - zn - ni - cu
The magnitude of contamination, regulatory compliance and annual loadings of soils with copper (Cu), zinc (Zn), cadmium (Cd), nickel (Ni), chromium (Cr) and lead (Pb) were determined at three sites in Harare where wastewater was used to irrigate vegetable gardens for at least 10 years. Heavy metal total concentrations (mg kg-1) in sandy and sandy–clay soils of pH 5.1–8.1 from all sites ranged from 7.0 to 145 for Cu, 14 to 228 for Zn, 0.5 to 3.4 for Cd,
Comparison of three sequential extraction procedures to describe metal fractionation in anaerobic granular sludges
Hullebusch, E.D. van; Sudarno, S. ; Zandvoort, M.H. ; Lens, P.N.L. - \ 2005
Talanta 65 (2005)2. - ISSN 0039-9140 - p. 549 - 558.
heavy-metals - sewage-sludge - chemical fractionation - sample pretreatment - potential mobility - molasses stillage - trace-metals - sediments - speciation - acid
In the last few decades. several sequential extraction procedures have been developed to quantify the chemical status of metals in the solid phase. In this study. three extraction techniques (modified [A. Tessier, P.G.C. Campbell, M. Bisson, Anal. Chem. 51 (1979) 844]: [R.C. Stover. L.E. Sommers, D.J. Silvera, J. Water Pollut. Con. F. 48 (1976) 2165]; and the Bureau Communautaire de Reference (BCR) [K.F. Mossop. C.M. Davidson. Anal. Chim. Acta 478 (2003) 111]) were applied to study the distribution of trace (Co, Ni, Zn and Cu) and major (Mn and Fe) elements in two different anaerobic granular sludges from full-scale methanogenic wastewater treatment plants. The Stover scheme displayed a higher number of fractions that induces a poor recovery compared to the other schemes. The sequential extraction scheme recommended by BCR and the modified Tessier scheme gave similar trends and are sufficiently repeatable and reproducible for application in fractionation studies. However, the BCR scheme seems to be of limited utilisation to study anaerobic matrixes because the extraction stage for its reducible fraction may release substantial amounts of trace elements bound to the organic/sulfides fraction, and consequently, the recovery of trace elements in the oxide fraction may be overestimated at the expense of the oxidisable fraction. As a final conclusion. the modified Tessier scheme seems to be the most suitable scheme to study the metal partitioning in anaerobic granular sludges. (C) 2004 Elsevier B.V. All rights reserved.