VOLUME 4, 2007
CONTENTS (January 2007, Volume 4/Number 1)
Research Strategies for Enzyme Dosing to Enhance Anaerobic Digestion of Sewage Sludge Å. DAVIDSSON, J. WAWRZYNCZYK, O. NORRLÖW and J. LA COUR JANSEN Production of Granular Activated Carbons from Pig Manure for Metal Ions Adsorption ISABEL Effect of Anaerobic Digestion and Anaerobic/Aerobic Digestion Processes on Sludge Dewatering SANGEETHA SUBRAMANIAN, NITIN KUMAR, SUDHIR MURTHY and JOHN T. NOVAK Demonstration of Combined Dewatering and Thermal Vacuum Drying of Municipal Residuals MOHAMMAD ABU-ORF, ROBERT JUNNIER, JOSHUA MAH and STEVEN DENTEL Dimensionless Groups as Scale-Up Parameter for Wastewater and Wastewater Sludge Treatment in a Stirred Tank Reactor MAUSAM VERMA, SATINDER K. BRAR, T. R. SREEKRISHNAN, R. D. TYAGI and R. Y. SURAMPALLI Use of a Natural Mineral for the Removal of Copper and Nickel from Aqueous Solutions to Reduce Heavy Metal Content of Precipitation Sludges VOLKAN ÇAGIN, NIHAN MORALI and IPEK IMAMOGLU Heavy Metal Concentrations of Atmospheric Ambient Deposition Dust in H. KURTULUS OZCAN, GOKSEL DEMIR, SEMIH NEMLIOGLU, NAIM SEZGIN and CUMA BAYAT ARTICLE ABSTRACTS (January 2007, Volume 4/Number 1) Strategies for Enzyme Dosing to Enhance Anaerobic Digestion of Sewage Sludge Å. DAVIDSSON, J. WAWRZYNCZYK, O. NORRLÖW and J. LA COUR JANSEN ABSTRACT: Enhancement of anaerobic digestion of sewage sludge by enzyme addition was demonstrated in batch digestion tests. A pre-hydrolysation step with addition of enzymes at controlled temperature during 4 hours was shown to increase the methane yield significantly. Further tests with direct feeding of enzymes together with fresh sludge to the digester gave the same effect of a methane yield increase. For implementation in full-scale, different strategies for adding the enzymes were tested in batch laboratory tests and pilot-scale continuous digestion. The addition to the inlet together with fresh sludge and addition with re-circulated digested sludge were compared. Both ways resulted in significant increases in methane production. The highest yield was achieved when enzymes were added together with fresh sludge in continuous pilot-scale digestion. Enzymatic treatment decreased the biomass vitality in the digester without reducing the methanogenic activity. Production of Granular Activated Carbons from Pig Manure for Metal Ions Adsorption ISABEL ABSTRACT: The current method of processing pig waste involves diluting it into large lagoons, which carries both environmental and human health risks. Alternatives to pig waste disposal are its reuse into value added products. This study produces activated carbons from swine manure and characterizes them in terms of physical, chemical and adsorptive properties. The process involves pyrolyzing and activating dry palletized swine manure under conditions effective to produce activated carbon. Brunauer-Emmett-Teller, BET surface areas for the resulting granular activated carbons ranged between 342 and 456 m2/g but no relationship was found between BET and adsorption. When compared to reference carbons made from coal, coconut shells or wood, experimental carbons were superior in their ability to adsorb metal ions, adsorbing two to three times more copper ion than their plant based counterparts and up to eight times more than carbons made from coal. Swine manure-based carbons demonstrated a preference towards ions of copper, followed by zinc and cadmium. It is postulated that negatively charged phosphate groups attached to the carbon skeleton are, at least in part responsible for their increased affinity towards positively charged metal ions. Effect of Anaerobic Digestion and Anaerobic/Aerobic Digestion Processes on Sludge Dewatering SANGEETHA SUBRAMANIAN, NITIN KUMAR, SUDHIR MURTHY and JOHN T. NOVAK ABSTRACT: Digestion processes are known to affect various sludge properties including total and volatile solids content, particle size distribution, extracellular polymeric substances concentration and composition, bound water content, and consequently the dewatering characteristics of sludge. Both aerobic and anaerobic digestion have been used to reduce the volatile solids content of waste sludges and each has advantages and disadvantages. In this study, sequential anaerobic/aerobic digestion was evaluated to determine if anaerobic digestion followed by aerobic digestion could improve volatile solids destruction and improve biosolids dewatering. The data showed that combined anaerobic/aerobic digestion could improve volatile solids destruction from 7 to 41% and polymer conditioning requirements could be reduced as much as 50% compared to anaerobic digestion alone. In addition, the required polymer dose decreased and the bound water content decreased, indicating that higher cake solids could be attained. Demonstration of Combined Dewatering and Thermal Vacuum Drying of Municipal Residuals MOHAMMAD ABU-ORF, ROBERT JUNNIER, JOSHUA MAH and STEVEN DENTEL ABSTRACT: Achieving dryer sludge cake for disposal or reuse is becoming both economical and desirable in many solids management programs. Sequential dewatering and drying processes have generally been required for this purpose. This paper reports on a technology that combines the two processes in a single step. The device modified a conventional recessed chamber filter press by increasing temperature and applying vacuum during filtration to produce a high percent solids cake. The research objective was to assess the device's effectiveness with municipal residuals. Four different biosolids and residuals were used in this study. Proper chemical conditioning was first determined for each residual type using bench scale jar testing procedures and a pressure filtration apparatus. Pilot scale testing was then conducted to determine the drying efficiency. Results showed that the dewatering and drying efficiency of the device primarily depends on the residual type and the selection of the right combination of conditioners. The pilot scale device achieved 85–97% solids dryness in about 5 hrs drying time. Neither the capillary suction time test nor the laboratory pressure filtration device were able to predict pilot scale performance. The device produces relatively uniform, dried cake solids, and without significant performance variation between chambers. However, solids throughput of the technology appears to be low. Dimensionless Groups as Scale-Up Parameter for Wastewater and Wastewater Sludge Treatment in a Stirred Tank Reactor MAUSAM VERMA, SATINDER K. BRAR, T. R. SREEKRISHNAN, R. D. TYAGI, and R. Y. SURAMPALLI ABSTRACT: Scale-up of a biological process can be carried out by utilizing several techniques depending upon the specific requirements. For instance, a mathematical modeling would be highly recommended if it is feasible to define the physics of a process by a mathematical equation. Likewise, a statistical model is recommended, if the mutual interactions of process parameters are difficult to explain based on theoretical ground. On the other hand, dimensional analysis could provide "scale-invariant" tool for reliable scale-up, if the mathematical formulation of the physical process is dimensionally homogenous. In this study, process parameters have been examined for determination of the best set of dimensionless group for municipal wastewater and wastewater sludge treatment in a stirred tank reactor. The relevance list generated following relationship among volumetric mass transfer coefficient (kLa), and other operational parameters. The ratio, kLa/N was defined as mass transfer number. The study utilized data from bench scale stirred tank reactor operations on wastewater sludge using Bacillus sp. as inoculum culture under aerobic conditions. Considering the greater dependency of the process on aeration and agitation, the results of 15 l stirred tank reactors were selected to determine the most important relationship between kLa and other operational parameters. On analyses of 15 l bioreactor results, the scale-up criteria suggested by this dimensional analysis proved to be a successful attempt. Thus the future experimentation on a higher scale reactor would be feasible. Use of a Natural Mineral for the Removal of Copper and Nickel from Aqueous Solutions to Reduce Heavy Metal Content of Precipitation Sludges VOLKAN ÇAGIN, NIHAN MORALI and IPEK IMAMOGLU ABSTRACT: A major disadvantage of precipitation removal of heavy metals is the disposal of sludge having a high concentration of heavy metals, sometimes requiring disposal in hazardous waste landfills. A sorption based polishing step using natural sorbents following precipitation may be feasible to avoid costly disposal of hazardous sludge. This study investigates the applicability of the use of a natural zeolite, namely clinoptilolite, obtained from a Western Anatolian deposit, in removing copper and nickel from aqueous solutions. Maximum achievable capacities were found as 0.31 meq Cu2+/g and 0.32 meq Ni2+/g for as-received, and 0.55 meq Cu2+/g and 0.43 meq Ni2+/g for conditioned clinoptilolite samples, respectively. Use of clinoptilolite for the removal of Cu2+ from precipitation effluents holds more potential for the purpose of meeting discharge standards. Metal removal mechanisms are also investigated via examination of exchangeable cations (Na+, K+, Mg2+, Ca2+) in the aqueous phase. Heavy Metal Concentrations of Atmospheric Ambient Deposition Dust in H. KURTULUS OZCAN, GOKSEL DEMIR, SEMIH NEMLIOGLU, NAIM SEZGIN and CUMA BAYAT ABSTRACT: Air Pollution emissions due to motor vehicle-related traffic on motorways are sent into the atmosphere. Along with many pollutants from motor vehicles because of fossile fuel usage, heavy metals are also emitted as particles with exhausted gas. Heavy metals are one of the important parameters among environmental pollution sources. Heavy metals from motor vehicles may be found as PM in motorway atmosphere and be involved in street dust by depositing on roads as atmospheric precipitates. Bridge tollhouses are one of the most closely encountered environments of human beings with this kind of dust. In this study, time-related changes of atmospheric precipitate depositing per unit area were determined on breathing height of tollhouse workers, as well as concentrations of lead (Pb), copper (Cu), zinc (Zn), cadmium (Cd), and nickel (Ni) were measured. The study area was Commentary Paradigms for Biosolids Management: Risk and Sustainability Based Models STEVEN K. DENTEL Feature Planning the Municipal Solid Waste Management: The Case of " LUDOVICO SPINOSA, ANTONELLO ANTONICELLI and MICHELE CUOMO Research Impact of Calcite on Phosphorus Removal and Recovery from Wastewater Using CSH-Filled Fixed Bed Filters U. BERG, A. EHBRECHT, E. RÖHM, P.G. WEIDLER and R. NÜESCH Assessment of Salmonella typhimurium Growth in Class A Biosolids and Soil/Biosolid Mixtures NOHELIA CASTRO-DEL CAMPO, IAN L. PEPPER and CHARLES P. GERBA Heavy Metal Amounts in Soil and Sediments of Surface Water Sources in the Industrial Regions of EMINE ELMASLAR OZBAS, H. KURTULUS OZCAN, NILGUN BALKAYA and GOKSEL DEMIR Biopesticide Production from Wastewater Sludge: Inoculum Age and Sludge Solids S. YAN, A. S. VIDYARTHI, R. D. TYAGI, J. R. VALÉRO, R.Y. SURAMPALLI and B.N. LOHANI Index Volume 3/2006 ARTICLE ABSTRACTS (April 2007, Volume 4/Number 2) Paradigms for Biosolids Management: Risk and Sustainability Based Models STEVEN K. DENTEL ABSTRACT: Policies established in the Planning the Municipal Solid Waste Management: The Case of " LUDOVICO SPINOSA, ANTONELLO ANTONICELLI and MICHELE CUOMO ABSTRACT: Waste management is one of the most critical issues facing modern society, also considered the need to apply reuse options instead of simple disposal ones. In the Apulia Region (I) a Commissariat for Environmental Emergency was established since 1997 having also the duty to develop a "Regional Plan for urban waste management" in conformity with European/National regulations. The Plan introduces technical criteria for qualification of recyclable fractions deriving from waste separate collection, and mechanical-biological treatment of waste remaining after separate collection. In this paper main lines of the Plan are discussed, and the first plant complying with Plan requirements described. Impact of Calcite on Phosphorus Removal and Recovery from Wastewater Using CSH-Filled Fixed Bed Filters U. BERG, A. EHBRECHT, E. RÖHM, P.G. WEIDLER and R. NÜESCH ABSTRACT: Phosphorus (P) resources expiring in the next ~100 years reveal the necessity to search for alternatives. Investigations focused on the P-recovery straight from wastewater in one single process by means of laboratory long-term column experiments using two carrier materials—calcium silicate hydrate (CSH) and calcite (cc). Both, pure materials and mixtures of both substrates were applied. The efficiency of the P-recovery process was significantly dominated by the CSH content. However, a considerable improvement of the P-elimination was affected by using two consecutive columns with pure materials, i.e. pre-filtration through a cc column. Hydroxylapatite-like products were formed as potential recyclables. Assessment of Salmonella typhimurium Growth in Class A Biosolids and Soil/Biosolid Mixtures NOHELIA CASTRO-DEL CAMPO, IAN L. PEPPER and CHARLES P. GERBA ABSTRACT: The potential of Salmonella typhimurium regrowth in Class A biosolid pellets and compost after land application was assessed. Mixtures of soil, soil plus biosolids, and biosolids were inoculated with two different concentrations and monitored during a period of 20 days. No Salmonella growth occurred in any of the soil/biosolid mixtures regardless of inoculum size or moisture content. No growth occurred in any of the biosolids with a moisture content of 20% except the pellets from Texas when inoculated with 10,000 colony forming units/g. Growth of Salmonella did occur in all of the Class A products under saturated conditions. Under all moisture conditions indigenous microflora increased in numbers in the biosolids, soil and biosolid/soil mixtures. In conclusion, these results suggest that while regrowth of Salmonella in biosolids may occur under saturated conditions it does not occur after Class A biosolids land application at typical agronomic rates. Heavy Metal Amounts in Soil and Sediments of Surface Water Sources in the Industrial Regions of EMINE ELMASLAR OZBAS, H. KURTULUS OZCAN, NILGUN BALKAYA, GOKSEL DEMIR and CUMA BAYAT ABSTRACT: Today, heavy metal-oriented soil pollution composes a substantial problem, especially in regions with dense industrial activities. Industrial wastes may also be introduced to superficial waters either directly or indirectly, forming a dense accumulation of heavy metal in aquatic sediments. Biopesticide Production fromWastewater Sludge: Inoculum Age and Sludge Solids S. YAN, A. S. VIDYARTHI, R. D. TYAGI, J. R. VALÉRO, R. Y. SURAMPALLI and B. N. LOHANI ABSTRACT: Production of Bacillus thuringiensis (Bt) based biopesticide was studied in shake flasks and in computer controlled 15L-fermentor using wastewater sludge as a sole raw material. Shake flask experiments with different inoculum age (9h, 12h, 15h and 18h) and inoculum growth medium were studied at suspended sludge solids concentration of 25 g.l-1. The process performance was assessed in terms of viable cell count (VC), viable spore count (VS) and entomotoxicity (ET). The best results in terms of highest VS (2.7E+09 cfu.ml-1) count and ET (10813 IU.µl-1) were observed using 12h old inoculum produced in two stages—1st stage—tryptic soya yeast extract (TSY) medium and 2nd stage in sludge. The TSY grown inoculum supported good growth in sludge medium but failed to attain the corresponding high ET. Bt production using different sludge solids concentration (from 20 g.l-1 to 35 g.l-1) was studied in fermentor under controlled conditions (pH, temperature and dissolved oxygen). The maximum ET (13587 IU.µl-1) was obtained with sludge solids of 25g.l-1 (dry weight basis) and did not change significantly with further increase in sludge solids. A drop in both VS count and ET value was observed at sludge solids of 35 g.l-1. A decrease in VS, VC and ET values at high solids concentration was due to inhibition by the sludge solids. Dissolved oxygen (DO) concentration was maintained above critical level in order to meet the oxygen requirement during fermentation. O2 transfer rate (OTR) and CO2 transfer rate (CTR) were measured by exit gas analysis during fermentation at 20 g.l-1 and 30 g.l-1 sludge solids. OTR values at higher SS were higher compared to lower SS. It was quite unexpected based on speculation from shake flask experiment that DO availability in the medium with high suspended solids might be low and thus it acted as one of the limiting parameter in Bt fermentation. Respiratory quotients (RQ) calculated based on OTR and CTR values in the fermentation system was also analysed.
Editors Comments Research Characterization of the Quality of Drying Bed Treated Biosolids in AKRUM H. TAMIMI, CHARLES P. GERBA, BASSAM HAYEK, CHRISTOPHER Y. CHOI and ROBERT J. FREITAS P-RoC-Phosphorus Recovery from Wa stewater by Crystallisation of Calcium Phosphate Compounds U. BERG, G. KNOLL, Concentrations of Nutrients and Heavy Metals in Cyclone Fly Ash from the Grate-Fired Boiler at a Small Municipal District Heating Plant (6 MW) RISTO PÖYKIÖ, HANNU NURMESNIEMI and OLLI DAHL Determination of Micro-Elements in Surface Water Resources AIDA SAHMUROVA, ATAKAN ONGEN, EMINE ELMASLAR OZBAS and NILGUN BALKAYA From "Fills" to Filter: Insights into the Reuse of Dewatered Alum Sludge as a Filter Media in a Constructed Wetland EA.O. BABATUNDE, Y.Q. ZHAO, Y. YANG and P. Application of Organic Acids to Reduce Helminth Ova Content in Physicochemical Sludge J.A. BARRIOS, B. JIMÉNEZ and C. MAYA Utilization of Extracellular Polymeric Substances for Removal of Heavy Metals from Contaminated Soils TIAN YU, ZHENG LEI and SUN DEZHI ARTICLE ABSTRACTS (July 2007, Volume 4/Number 3) Characterization of the Quality of Drying Bed Treated Biosolids in AKRUM H. TAMIMI, CHARLES P. GERBA, BASSAM HAYEK, CHRISTOPHER Y. CHOI and ROBERT J. FREITAS ABSTRACT: Disposal of liquid and dewatered sludge at storage sites and landfills is currently the most widely practiced method dealing with biosolids in P-RoC - Phosphorus Recovery from Wastewater by Crystallisation of Calcium Phosphate Compounds U. BERG, G. KNOLL, ABSTRACT: The P-RoC process—the phosphorus recovery from wastewater by crystallisation of calcium phosphate—was developed in order to simultaneously remove and recover phosphorus (P) from waste- and process waters by applying calcium silicate hydrate (CSH) compounds. Experiments were performed in fixed bed- and stirred reactors, both in laboratory- and semi-technical scale. Total P (P-tot) contents of the crystallisation products of at least 24 wt-%P-tot were achieved. X-ray diffraction analysis proved the formation of hydroxylapatite (HAP, Ca5(PO4)3OH) using municipal wastewater and of brushite (CaHPO4*2H2O) using industrial process water. Reuse options of the generated products as P-rock substitute and/or fertiliser are conceivable. Concentrations of Nutrients and Heavy Metals in Cyclone Fly Ash from the Grate-Fired Boiler at a Small Municipal District Heating Plant (6MW) RISTO PÖYKIÖ, HANNU NURMESNIEMI and OLLI DAHL ABSTRACT: Combustion acts like a thermodynamic separation process for the different inorganic materials in the fuel. Elements with a low volatility will concentrate in the bottom ash, while more volatile elements will concentrate in the fly ash. The consequence of separation effect in combustion plant is that the different ash fractions have a different chemical composition, and are therefore variably suited for utilization as a secondary raw material with fertilizing and liming effects in forestry and in agriculture. According to the enrichment factor, which is the ratio of element concentrations in the cyclone fly ash to those in the ash collected from the outlet of the biomass-fired system (i.e. bottom ash), the concentrations of the heavy metals in the cyclone fly ash were within 1.3–41 times higher than those in the bottom ash. The total Cd, Cr, Zn and Hg concentrations in the cyclone fly ash exceeded the new Finnish limit values for fertilizers in agricultural use. In addition, the total concentrations of Cd, Cu and Hg in the cyclone fly ash exceeded the new Finnish limit values for forestry fertilizers. Both limit values came into force in March 2007. Due to enrichment of heavy metals in the cyclone fly ash, it cannot be used as an agricultural or forestry fertilizer. Determination of Micro-Elements in Surface Water Resources AIDA SAHMUROVA, ATAKAN ONGEN, EMINE ELMASLAR OZBAS and NILGUN BALKAYA ABSTRACT: The basic resources of microelements that are essential for human life. However, in larger or lower amounts, they may become important and critical. They may accumulate in biological systems and become a significant health hazard. Biochemical and physical adaptation of microorganisms is related to geophysical properties and the environmental factors in the surrounding habitat. Therefore many research studies have been conducted dealing microelements and their effect on ecosystems. In this study, heavy metal contamination in the samples taken from surface water resources in the From "Fills" to Filter: Insights into the Reuse of Dewatered Alum Sludge as a Filter Media in a Constructed Wetland A.O. BABATUNDE, Y.Q. ZHAO, Y. YANG and P. ABSTRACT: Dewatered alum sludge, a by-product of drinking water treatment plants, hitherto consigned to landfills was used to develop a novel bio-filter in form of a constructed wetland. Performance results have demonstrated the benefits of the alum sludge cakes in a lab-scale system in enhancing phosphorus (P) removal from an animal farm wastewater. Although P and organic matter were concurrently removed in the system, there was a probable "one off" release of organics from the system, and this coincided with an increase in inlet P concentration from 39.2 mg-P/l to 163.0 mg-P/l. A conceptual model was then proposed to explain and discuss this. Application of Organic Acids to Reduce Helminth Ova Content in Physicochemical Sludge J.A. BARRIOS, B. JIMÉNEZ and C. MAYA ABSTRACT: New criteria are being developed for the safe use of wastewater and other sources of water and/or nutrients in agriculture that may be in the future adapted to sludge reuse. In particular, helminths are of concern because they infect an estimated of 1.25 billion people worldwide and their ova are highly resistant. However, organic acids have demonstrated their effectiveness to inactivate them, as well as different microorganisms, but their effect on actual sludge samples with high concentrations of helminth ova is rarely documented. To compare the effect of acetic and peracetic acids (PAA), samples were treated with 22,000 ppm and 550 ppm, respectively, and the inactivation of helminth ova was monitored at different contact times (2–30 min). Acetic acid inactivated 81% of viable helminth ova but still could not meet the limit of the Mexican regulation (35 total ova/g TS). Apparently, its effect is based on the diffusion through the membrane that inhibits protein response and causes toxic conditions. In contrast, peracetic acid reached 93% of inactivation and achieved concentrations of less than 10 viable ova/g TS. Microscope observations indicated that PAA breaks the operculum of Ascaris suum eggs by oxidation with the free oxygen released. Utilization of Extracellular Polymeric Substances for Removal of Heavy Metals from Contaminated Soils TIAN YU, ZHENG LEI and SUN DEZHI ABSTRACT: In order to evaluate extracellular polymeric substances (EPS) for their effectiveness in removing heavy metals from contaminated soils, we examined the effect of concentration of EPS, initial pH of EPS solution and duration of EPS treatment for identification of the best way to achieve efficient removal of heavy metals from contaminated soils, compare the fraction distributions of heavy metals in soils before and after EPS treatment for determination of optimal remedying conditions, and study the kinetics of heavy metal extraction by EPS from contaminated soils for a better understanding of the remediation process. Our findings include EPS can be used to remove 83% of Cd, 45% of Pb and 48% of Zn from contaminated soils at an initial pH of 7–8 and a concentration of 180mg/L in 24 hours; metal-ion removal process can bemodeled by fast and slow reactions, and the order of rate constant is Cd>Zn>Pb for fast reaction and Cd>Pb>Zn for slow reaction; EPS is more effective in removing the organically bound and carbonate fractions of heavy metals from contaminated soils. Our conclusion is therefore that, as a promising extractant, EPS can be used for removal of heavy metals from contaminated soils.
Editors Note Research Historical Development of Sludge Management in AYSE FILIBELI and AZIZE AYOL Different Approaches for Prospective Sludge Management Incorporating Phosphorus Recovery D. MONTAG, K. GETHKE and J. PINNEKAMP Wastewater Sludge as a Raw Material for Biopesticides Production—Impact of Seasonal Variations S. YAN, S. BALA SUBRAMANIAN, S. MOHAMMEDI, R. D. TYAGI, R. Y. SURAMPALLI and B. N. LOHANI Zirconium Mesostructures Entrapped in Calcium Alginate for Treating Phosphate Ion in Reject Water After Sludge Dewatering K. H. YEON, S. LEE, Y. M. PARK, Y. S. CHOI and S. H. LEE Reduction of the Quantity of Sewage Sludge and Increase in the Digester Gas Production KARL-GEORG SCHMELZ, ANJA REIPA and DANIEL ROSSOL Stabilization/Solidification of Electroplating Sludge using Cement/Silica Fume V. SHAPOURI, M. R. ALAVI MOGHADAM and T. EBADI Improvement of the Sedimentation and Dewatering Properties o f Water Treatment Sludges by Application of a Non Conventional Flocculant: Basaltic Dust Produced in an Asphaltic Plant R. M. R. ZAMORA, F. N. MARTÍNEZ and A. D. MORENO ARTICLE ABSTRACTS (October 2007, Volume 4/Number 4) Historical Development of Sludge Management in AYSE FILIBELI and AZIZE AYOL ABSTRACT: Advances in the field of sustainable management of natural resources made possible the enhanced understanding on the exchanges between human activities and ecological, earth and ocean systems. With the realization of the changes in the nature, human being tried to find the way lessening the damages given to the natural sources by the human activities. Depending on the social demands and environmental reasons, many strategies on the issues like water and wastewater treatment, waste management, air pollution have been developed by the communities. Recently, sludge related problems took place as one of the most challenging environmental problems in Worldwide. This paper explores historical development of sludge management in Different Approaches for Prospective Sludge Management Incorporating Phosphorus Recovery D. MONTAG, K. GETHKE and J. PINNEKAMP ABSTRACT: By the end of this century phosphate deposits with low concentrations of hazardous substances, first of all cadmium and uranium, will be totally exploited. As phosphates cannot be substituted for plant nutrition by other substances, usage of secondary phosphate materials is becoming more and more important. At the Institute of Environmental Engineering of RWTH Aachen University several approaches for phosphate recovery have been investigated and developed. The PRISA process can be integrated into the sludge treatment of a municipal wastewater treatment plant (wwtp), whereas the RPA process is attached to a mono-incineration of the sewage sludge. Related to the phosphorus inflow load to the wwtp, the processes enable a recovery up to 40 and 80%, respectively. The recovered phosphate can be used either in agriculture or can be sold to the phosphate industry. Both processes can be recommended as possibilities for sustainable sludge management in the future. Wastewater Sludge as a Raw Material for Biopesticides Production—Impact of Seasonal Variations S. YAN, S. BALA SUBRAMANIAN, S. MOHAMMEDI, R. D. TYAGI, R. Y. SURAMPALLI and B. N. LOHANI ABSTRACT: Wastewater sludge is a very good nutritional source for growth of industrial microorganisms to produce value added products such as Bacillus thuringiensis (Bt) based biopesticides. Biopesticides production using synthetic medium is expensive. Therefore sludge (containing high nutritive values) could replace the commercial synthetic medium, which is economical due to low or zero cost of the raw material. Due to extreme seasonal variations in municipal wastewater treatment plants, the sludge characteristics may change and consequently affect the biopesticide yield when sludge is used as a raw material. Therefore, it was essential to study the reproducibility of entomotoxicity and other Bt growth related parameters with seasonal variations of sludge characteristics. Municipal wastewater sludge samples were collected from wastewater treatment plant over a period of one year at different times and were used for the production of Bacillus thuringiensis (Bt kurstaki HD-1) based biopesticide in shake flask experiments. The composition of sludge was found to vary during different seasons. The progress of biopesticide production process was studied by measuring total viable cell count (TC), total viable spore count (VS) and entomotoxicity (Tx). The values of TC varied from 6.00E+07 to 2.40E+08CFU/ml, the generation time changed between 0.8 to 1.3 h and sporulation varied from 80–88%. The entomotoxicity value also varied but the variation was not high. There was no correlation of entomotoxicity with spore or viable cell concentration. Zirconium Mesostructures Entrapped in Calcium Alginate for Treating Phosphate Ion in Reject Water After Sludge Dewatering K. H. YEON, S. LEE, Y. M. PARK, Y. S. CHOI and S. H. LEE ABSTRACT: The zirconium mesostructures (ZM), which have a high sorption capacity for phosphate in its original powder form, were molded by calcium alginate to have a bead form for practical application. And the ZM bead was estimated as a potential adsorbent for the phosphate in reject water after sludge dewatering by varying ZM contents in it and its particle size. It was found that more than 99% of phosphate could be removed under optimal conditions using ZM beads. The maximum sorption capacity of ZM beads for the single-existing phosphate in distilled water was estimated to be 56.7 mg/g. Even though the ZM bead had 1.8 times lower phosphate sorption capacity than the equivalent original ZM powder, it still showed 2.2 times higher capacity than the existing anion adsorbent like activated alumina. This study showed that ZM bead could be used as a promising adsorbent for treating the phosphate in the reject water after sludge dewatering. Reduction of the Quantity of Sewage Sludge and Increase in the Digester Gas Production KARL-GEORG SCHMELZ*, ANJA REIPA and DANIEL ROSSOL ABSTRACT: Almost half the operating costs in German wastewater treatment plants fall to the areas "Energy" and "Treatment and disposal of sewage sludge". Therefore, with the Emschergenossenschaft and Lippeverband, various innovative processes have been tested for the reduction of the quantity of sewage sludge and for the increase in production of digester gas and energy. Sewage sludge disintegration, using various processes (ball mills, ultrasonic waves, lysate centrifuges and ozone), has been applied on a large-scale in parallel operation. Increases of the degree of degradation and of gas production up to a maximum of 20% could be achieved. However, as a rule, this is not sufficient in order to reclaim the energy and to reduce the quantity of sewage sludge to such an extent that an economical solution results. The addition of enzymes has also been investigated in a large-scale parallel operation. The positive effects determined (increase of the degree of degradation and of the production of digester gas) were here also too small for an economical application. Sewage sludge digestion at increased temperature (up to 45°C) has been investigated in semi-industrial parallel trials. An increase of the degree of degradation and of the digester gas production could also be established, however, the dewatering capability of the sludge deteriorated. The quantity of sludge could also be reduced through an aerobic post-treatment of the digested sludge and even the dewatering capability could be improved. At the same time the nitrogen return loading of the wastewater treatment plant can be reduced. Nevertheless, based on the results of the large-scale trials, no economic efficiency is achieved for the process. Through co-fermentation (joint treatment of biogenic wastes in the digester) the production of digester gas can be increased strongly. For more than two years wastes containing fats have been jointly treated in the Stabilization/Solidification of Electroplating Sludge using Cement/Silica Fume V. SHAPOURI, M. R. ALAVI MOGHADAM, and T. EBADI ABSTRACT: Stabilization/Solidification (S/S) is used as a pre-lanfilling waste treatment technology that aims to hazardous wastes safe for disposal. Inorganic binders such as cement are widely used as an appropriate binder for S/S treatment of hazardous waste. In this study cement and silica fume were used to stabilize hexavalent chromium present in the electroplating sludge. The degree of chromium stabilization was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) Test, Compression Test and XRD analysis .The specimens were prepared based on various Cr+6 concentration in sludge (12,6,1 gr/l ). The results showed that the chromium concentration in leaching solution for 12 and 6 g/lCr+6 in sludge is more than the maximum contaminated level (5 mg/l) in TCLP test after 90 days curing . The obtained result showed that the average Cr+6 fixation was about 90% which seems to be acceptable for the present situation of electroplating sludge disposal in Iran. As the matrix of cement paste, the addition of sludge containing 12 gr/l Cr+6 encouraged the formation of CaCrO4.H2O, as observed through XRD analysis. Another obtained data showed that the partial replacement of cement with 10% silica fume increased the efficiency of Cr+6 fixation and compensate any negative effects caused by sludge on cement hydration. It should be mentioned that the compressive strength amounts of all samples are more than the minimum EPA compressive strength for stabilized wastes (3.5 Kg/Cm2). Improvement of the Sedimentation and Dewatering Properties of Water Treatment Sludges by Application of a Non Conventional Flocculant: Basaltic Dust Produced in an Asphaltic Plant R. M. R. ZAMORA, F. N. MARTÍNEZ and A. D. MORENO ABSTRACT: The assessment of the feasibility to valorize basaltic dust as flocculants additives in order to improve the sedimentation and dewatering characteristics of drinking water sludges was outlined as general objective in this research. The experimental study was divided in three stages: (1) sampling and physicochemical characterisation of basaltic dust (colour, density, oxides content, electronic microscopy, etc.), (2) optimization of the coagulant dose applied in the coagulation-flocculation process by using of the basaltic dust as flocculant and (3) physico-chemical characterisation of sludges produced in jar tests using basaltic dusts and raw water. The physicochemical characterisation of the basaltic dust (Corrosivity, Reactivity, Explosiviness, Toxicity, In flammability and Biological Risk) showed that this material was not a hazardous waste. Density, oxides content and particle size values of this material were similar to those reported for activated silica (a conventional inorganic flocculant). Basaltic dust improved sedimentation rate, filtration time and specific resistance to filtration from 2 to 5 times with respect to the values obtained for those experiments carried out without dust. The basaltic dust also reduced 60 % the coagulant dose (decreased from 25 to 10 mg/L Al2(SO4)3), employed in order to meet the Mexican standards for drinking water.
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