CONTENTS (January 2009, Volume 6/Number 1) Editorial Selected Papers Presented During ECSM'08—European Conference on Sludge Management, Liège, September 1–2, 2008 ANGÉLIQUE LÉONARD and MICHEL CRINE Research Effect of CaO and Dolomite Additive on the Thermal Decomposition of Sewage Sludge in an Inert Atmosphere T. BEDYK, L. NOWICKI, P. STOLAREK and S. LEDAKOWICZ Enhancement of Thermophilic Anaerobic Sludge Digestion by 70ºC Pre-Treatment: Energy Considerations I. FERRER, E. SERRANO, S. PONSÁ, F. VÁZQUEZ and X. FONT Activated Sludge Properties After Ultrasonic and Thermal Treatments and Their Potential Influence on Dewaterability J. LAURENT,M. PIERRA, M. CASELLAS,M.N. PONS and C. DAGOT Evaluation of Different Sludge Mechanical Dewatering Technologies D. MAMAIS, A. TZIMAS, A. EFTHIMIADOU, J. KISSANDRAKIS and A. ANDREADAKIS Bio-Fuels and Bio-Char Production from Pyrolysis of Sewage Sludge M.E. SÁNCHEZ, E. LINDAO, D. MARGALEFF, O. MARTÍNEZ and A.MORÁN Influence of Source and Treatment Method on the Properties of Activated Carbons Produced from Sewage Sludge S. PULLKET, K. M. SMITH, G. D. FOWLER and N.J.D. GRAHAM Improved Dewatering by Hydrothermal Conversion of Sludge H. SAVEYN, D. CURVERS, M. SCHOUTTETEN, E. KROTT and P. VAN DER MEEREN Sludge Drying Reed Beds: A Case Study E. UGGETTI, E. LLORENS, A. PEDESCOLL, I. FERRER, R. CASTELLNOU and J. GARCÍA ARTICLE ABSTRACTS (January 2009, Volume 6/Number 1) Effect of CaO and Dolomite Additive on the Thermal Decomposition of Sewage Sludge in an Inert Atmosphere T. BEDYK, L. NOWICKI, P. STOLAREK and S. LEDAKOWICZ ABSTRACT: The synchronised and calibrated measurement system consisting of thermobalance coupled with mass spectrometer was used in the study of sewage sludge pyrolysis. A sample of dried and sieved sewage sludge had been mixed with mineral additives (calcium oxide or dolomite) in different proportions and then heated up to 1000°C with constant heating rate in the atmosphere of argon. The aim of this work was to compare the thermal decomposition of sewage sludge with and without addition of catalyst and to qualitatively describe phenomena occurred. Adding of CaO or dolomite to the sludge sample we achieved: decrease of residual mass and tars production, an increase of CO and H2 amount. Enhancement of Thermophilic Anaerobic Sludge Digestion by 70ºC Pre-Treatment: Energy Considerations I. FERRER, E. SERRANO, S. PONSÁ, F. VÁZQUEZ and X. FONT ABSTRACT: The objective of this work was to investigate the effect of a low temperature pre-treatment (70°C) on the thermophilic anaerobic digestion of sewage sludge. Experimental results were used for the calculation of theoretical energy balances of full-scale digesters with and without pre-treatment step. The 70°C sludge pre-treatment increased sludge solubilization by 10 times and enhanced volatile fatty acids generation. Biogas production increased up to 30–40% and methane content in biogas from 64 to 68–70%. Theoretical calculations showed that additional surplus energy production would be expected by incorporating a 70°C pre-treatment step to a thermophilic reactor. Activated Sludge Properties After Ultrasonic and Thermal Treatments and Their Potential Influence on Dewaterability J. LAURENT, M. PIERRA, M. CASELLAS, M.N. PONS and C. DAGOT ABSTRACT: Two excess sludge reduction processes (ultrasounds and thermal) were studied with specific attention to some physico-chemical characteristics of treated sludge. Several parameters were monitored and discussed in respect to process efficiency and implications to dewaterability of excess sludge generated. Release of biopolymers, floc size reduction, transfer of ionizable functional groups in the liquid fraction and decrease of relative hydrophobicity were observed. According to the applied treatment, these modifications may improve or worsen the sludge dewaterability properties. Evaluation of Different Sludge Mechanical Dewatering Technologies D. MAMAIS, A. TZIMAS, A. EFTHIMIADOU, J. KISSANDRAKIS and A. ANDREADAKIS ABSTRACT: The two most dominant technologies in sludge dewatering are belt filter presses and centrifuges. The objective of this work is to evaluate the two technologies in parallel operation, using full scale data from two wastewater treatment plants of different size. According to the data obtained, centrifuges produced a drier cake and exhibited slightly lower polymer requirements compared to belt filter presses. Based on a cost analysis performed, the annual sludge dewatering and disposal cost for a small to medium size and a medium to large size WWTP was higher for the belt filter press and ranged from 106–147 €/ton DS versus 82–114 €/ton DS for the centrifuge dewatering system. Bio-Fuels and Bio-Char Production from Pyrolysis of Sewage Sludge M.E. SÁNCHEZ, E. LINDAO, D. MARGALEFF, O. MARTÍNEZ and A. MORÁN ABSTRACT: The limited reserves of fossil fuels along with the environmental concern about green-house gases have led to the search for new energy sources. Biomass offers a sustainable and renewable energy system. Sewage sludge, a residue generated in wastewater treatment plants, is one of the environmental problems in industrialized countries. Its contents of volatilematter represents a valuable resource, a possible reuse is the conversion into fuels by means of pyrolysis that yields gas, bio-oil and biochar. The composition and heating value of the gas makes it suitable for use as a fuel. The bio-oil may be evaluated as an environmentally-friendly green biofuel. The biochar product is carbon-rich and a potential solid biofuel. Other ways it might be used as a C and N source in soil amendment. Influence of Source and Treatment Method on the Properties of Activated Carbons Produced from Sewage Sludge S. PULLKET, K. M. SMITH, G. D. FOWLER and N.J.D. GRAHAM ABSTRACT: This paper reports an investigation into the effects of the geographical origins of sludge and the treatment methods applied to it on its properties as a feedstock for producing activated carbons. The approach taken firstly utilizes a response surface methodology (RSM) to model the relationship between the activation conditions and the textural characteristics of the carbons produced from two different Improved Dewatering by Hydrothermal Conversion of Sludge H. SAVEYN, D. CURVERS, M. SCHOUTTETEN, E. KROTT and P. VAN DER MEEREN ABSTRACT: A growing demand for renewable energy resources, together with increasing criticism on the competition with food crop production caused by current production methods, has stimulated new interest for fuel production from sewage sludge. One of the processes to recover fuel from sludge is hydrothermal conversion (HTC), whereby the wet sludge undergoes a high temperature/high pressure treatment, with the possible addition of catalysts. In this study, the influence of subcritical HTC treatment with regard to sludge dewaterability was investigated. A range of different temperatures (150–240°C), pH values (3–11), and peroxide additions (0–150% of COD) were studied. It was shown that after hydrothermal treatment of sludge or predewatered sludge cake and subsequent mechanical dewatering, dry matter contents of up to 60% could be obtained, and that the cake mass after HTC decreased by a factor of 5 on average, compared to the untreated sludge. The HTC process also resulted in an enrichment of the inorganic matter in the final cakes, by solubilization of the organic matter into an easily biodegradable form. The energy demand of the HTC process was low compared to drying by evaporation and might be partially provided by biofuels generated in the process, according to energetic calculations. Sludge Drying Reed Beds: A Case Study E. UGGETTI, E. LLORENS, A. PEDESCOLL, I. FERRER, R. CASTELLNOU and J. GARCÍA ABSTRACT: Sludge drying reed beds stand as a suitable technology for sludge management in certain situations. This work examines two full-scale sludge drying reed beds systems located in a Mediterranean region. Samples of influent sludge and sludge accumulated in the reed beds were analyzed for total solids (TS), volatile solids (VS), chemical oxygen demand, nutrients, heavy metals and faecal bacteria indicators. The results show a high dewatering degree (from 1–3 to 20–22%TS), progressive organic matter removal (10–30% VS/TS) and sludge mineralization during sludge storage. The concentration of nutrients, heavy metals and faecal bacteria indicators suggest a good quality of the sludge for land application. CONTENTS (April 2009, Volume 6/Number 2) Research Evaluation of Airborne Endotoxin Concentrations Associated with Management of a Crop Grown on Applied Biosolids E. BARTH, R. HERRMANN, T. DAHLING, R. BRENNER, S. WRIGHT and P. CLARK Determination of Optimum Polymer Dose for Single and Dual Polymer Conditioning of Wastewater Sludge AUDREY MURRAY and BANU ÖRMECI Adsorption of Hexavalent Chromium from Aqueous Solutions by Compost: Adsorption Equilibrium and Kinetics MAHBOOBEH NAMENI, MOHAMMAD REZA ALAVI MOGHADDAM and MOKHTAR ARAMI Evaluation of Trace Element Concentrations in Groundwater and Classification of Endemic Disease Regions using Multilayer Perceptron Neural Network AIDA SAHMUROVA, NIYAZI KILIC, ISIL OKAN and OSMAN N. UCAN Impact of Bioreactor Landfill Leachate Quality on As, Cd, Pb and Zn Leaching from Mine Residues THABET TOLAYMAT, SOUHAIL R. AL-ABED and G. JEGADEESAN ARTICLE ABSTRACTS (April 2009, Volume 6/Number 2) Evaluation of Airborne Endotoxin Concentrations Associated with Management of a Crop Grown on Applied Biosolids E. BARTH, R. HERRMANN, T. DAHLING, R. BRENNER, S. WRIGHT and P. CLARK ABSTRACT: Public health concerns have been expressed regarding inhalation exposure associated with the application of biosolids on cropland, which is due to the potential aerosolization of microorganisms, cell wall products, volatile chemicals, and nuisance odors. Endotoxin is a component of the cell walls of Gram-negative bacteria and is likely present in many biosolids. The application of biosolids to cropland may result in an immediate exposure or a delayed exposure to these microbial agents, such as when the crops are harvested. Upwind and downwind airborne concentrations of endotoxin were compared among and within two adjacent established hayfields, one with and one without previously applied biosolids, during grass raking and bailing activities. The mean downwind concentration of airborne endotoxin was significantly higher than the mean upwind concentration at the site where biosolids had been previously applied. The mean downwind concentration of endotoxin was not significantly different than the mean upwind concentration at the control field where biosolids had not previously been applied. When comparing the mean concentrations of airborne endotoxin among the sites, significant main effects were noticed for wind direction and field type, and an interactive effect was noticed for direction and field type. It is not known if the increased mean concentration of endotoxin associated with the downwind air samples at the applied biosolids field were due to the residual biosolids that were previously applied or due to endotoxin associated with plant material. The results apply to this investigation only since there was no treatment replication of each type of field. The downwind endotoxin concentrations observed during the raking and bailing activities were lower than various health effects criteria that have been recommended for airborne endotoxin. Determination of Optimum Polymer Dose for Single and Dual Polymer Conditioning of Wastewater Sludge AUDREY MURRAY and BANU ÖRMECI ABSTRACT: Determination of the optimum dose for a dual-polymer system is more difficult than for a single polymer system, and there has been little research in this area. This study investigates rheology as a possible tool for the determination of optimum dose for single and dual polymer conditioning. The rheogram peaks observed after polymer injection were analyzed and correlated to the optimum polymer dose. The results showed that dual polymer conditioning achieved better dewatering at lower conditioner doses, and torque rheology provides a promising tool for the determination of optimum dose and optimum combination of polymers in dual polymer systems. Adsorption of Hexavalent Chromium from Aqueous Solutions by Compost: Adsorption Equilibrium and Kinetics MAHBOOBEH NAMENI, MOHAMMAD REZA ALAVI MOGHADDAM, and MOKHTAR ARAMI ABSTRACT: In this research, adsorption of Cr(VI) on municipal compost has been studied. The main objectives are (1) investigating chromium adsorption from aqueous solutions by compost, (2) studying the influence of contact time, pH and initial chromium concentration on adsorption process and (3) determining appropriate adsorption isotherm and kinetics parameters of Cr(VI) adsorption. The results showed that a reasonable adsorption of chromium obtained after 180 minutes. Higher chromium Adsorption observed in lower pHs, and maximum chromium removal (74.63%) obtained in pH = 2. The adsorption of chromium by compost decreased at the higher initial chromium concentration. The adsorption process follows Freundlich isotherm equation (R2 = 0.976) and the pseudo-second order kinetic model. Evaluation of Trace Element Concentrations in Groundwater and Classification of Endemic Disease Regions using Multilayer Perceptron Neural Network AIDA SAHMUROVA, NIYAZI KILIC, ISIL OKAN, FERHAT KARACA and OSMAN N. UCAN ABSTRACT: In this study, trace elements were measured in the groundwater in Impact of Bioreactor Landfill Leachate Quality on As, Cd, Pb and Zn Leaching fromMine Residues THABET TOLAYMAT, SOUHAIL R. AL-ABED and G. JEGADEESAN ABSTRACT: In this paper, leaching of heavy metals (As, Cd, Pb and Zn) from two different metal rich wastes, namely mineral processing waste (W2) and waste derived fertilizer (W1) in batch extraction tests (TCLP, SPLP and deionized water) is presented. In addition, extraction tests using bioreactor MSW landfill leachates were also performed and results compared to the standardized tests. It was observed that the W1 (commercially available as Ironite) failed the TCLP tests, with Pb extract concentration (7.3 mg/L) higher than the TC limit. On the other hand, theW2passed the TCLP test. Significant differences in arsenic leaching fromW1 in the SPLP and deionized water extraction tests, compared to the TCLP tests reiterated the fact that TCLP underestimated the leachability of arsenic. Batch extraction tests using MSW landfill leachates were also performed. Landfill leachates were sampled from conventional (dry-tomb) and bioreactor facultative landfills. Leaching results indicated that TCLP overestimated Cd and Pb leaching in landfills. A comparison of all the batch extraction tests showed that leaching of heavy metals showed high pH dependency, with increased leaching in the acidic region (SPLP and deionized water tests). It was also observed that the dissolved organic carbon content and the volatile fatty acid content regulated the amount of heavy metals leached.
Editorial Selected Papers Presented during the IWA-Sludge Conference Held in P. BRENT DUNCAN Research Can Capillary Suction Time be an Indicator for Sludge Disintegration? ONUR GÜVEN APUL, ILGIN DOGAN and F. DILEK SANIN Characteristics of Different Extracellular Polymeric Substances (EPS) Fractions of Sludge Flocs from Brewery Wastewater Treatment Plant (WWTP) G.H. YU, P.J. HE and L.M. SHAO Characteristics of Ecological Stabilized Sewage Sludge (I) Y. B. CUI, ZH. X. QI, ZH. Q. GUO and T. L. JIANG Characteristics of Organic Matters during Anaerobic Digestion of Ultrasonically Pretreated Sludge and the Effects on Sludge Dewaterability HUACHENG XU, PINJING HE and LIMING SHAO Experimental Research on Treatment of Housing Estate Wastewater by Non-Residual Sludge Hydrolytic Acidification Process HONG-JUN HAN, CHUN-YAN MA and BING WANG Investigation into the Fate of a Metabolic Uncoupler, 2,6-dichlorophenol in the Sequence Batch Reactor System YU TIAN, ZHIPENG LI, JUN ZHANG and DI WU Mechanochemical and Biological Degradation of PCB in Contaminated Marine Sediments G. CAGNETTA, G. INTINI, L. LIBERTI, M. NOTARNICOLA, L. SPINOSA and P. STELLACCI Moisture Removal Mechanism of Sludge Conditioning by Freeze-Thaw Process HSING-SHANG LEE, JIANN-LONG CHEN, KUNG-YUH CHIANG, CHIH-CHAO WU and CHENG-LIANG CHEN On the Necessity of Sludge Conditioning with Non-organic Polymer: AOP Approach Y.Q. ZHAO, C. KEOGH and MAHA A. TONY Optimized Coagulation on a Municipal Wastewater Treatment: Competitive and Synergetic Effect Among Different Pollutants DONGSHENG WANG, XUZHENG XU, ZEQUN LIU, XUELIN GU and GUOREN XU Ultrasonic lysis of Biological Sludge: A Three-stage Process G. ZHANG, P. ZHANG, X. KANG and F. GAO ARTICLE ABSTRACTS (July 2009, Volume 6/Number 3) Can Capillary Suction Time be an Indicator for Sludge Disintegration? ONUR GÜVEN APUL, ILGIN DOGAN and F. DILEK SANIN ABSTRACT: Sludge disintegration is a tool for sludge minimization goal. Sludge disintegration (or sludge pretreatment) principally converts the waste activated sludge into a more bioavailable form prior to anaerobic digestion and contributes to the enhancement of anaerobic digestion. The indicator of success for sludge disintegration is generally taken as the concentration of released organics to the liquid phase. There are different examples of expressing the success of disintegration; such as degree of disintegration, soluble COD release, ratio of soluble to total COD, the released sCOD per unit amount of solids present or constituents of released sCOD. Capillary suction time (CST) is a simple method used to measure dewaterability of sludge samples. Relationship between dewaterability measured by CST and a number of sludge properties such particle size, bound water content, etc. has been shown in the past. Therefore, this study investigates whether CST can be used to express the effectiveness of sludge disintegration. For this purpose a number of sludge pretreatment techniques were tested and correlations between CST and sCOD were analyzed. Results show that CST can act as a good indicator of disintegration for some pretreatment methods but is not useful for indicating the disintegration levels if any of the pretreatment method involves some sort of conditioning. Characteristics of Different Extracellular Polymeric Substances (EPS) Fractions of Sludge Flocs from Brewery Wastewater Treatment Plant (WWTP) G.H. YU, P.J. HE and L.M. SHAO ABSTRACT: Distributions of extracellular enzymes, proteins (PN), and polysaccharides (PS) in the different extracellular polymeric substances (EPS) fractions of sludge flocs affect the wastewater treatment capability. The results showed that PN, PS, and extracellular enzyme had a distinct distribution pattern in the different EPS fractions. Both fourier transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC) further suggested the difference of EPS fractions. These results suggest that by changing the distribution pattern of PN, PS, and extracellular enzyme, with some pretreatments before aerobic/anaerobic digestion, the performance of brewery wastewater treatment may be improved. Characteristics of Ecological Stabilized Sewage Sludge (I) Y. B. CUI, ZH. X. QI, ZH. Q. GUO and T. L. JIANG ABSTRACT: Ecological stabilization pilot scale experiment was conducted for wastewater sludge treatment. The study was performed over the period from June to November in 2005 and from May to November in 2006 on a bed with 80m2, which located in the third wastewater treatment plant, Characteristics of Organic Matters During Anaerobic Digestion of Ultrasonically Pretreated Sludge and the Effects on Sludge Dewaterability HUACHENG XU, PINJING HE and LIMING SHAO ABSTRACT: The present study evaluated the sludge dewaterability and further explored the relationship between the sludge dewaterability and the molecule weights (MW) of organic matters in the different fractions of sludge flocs. The sewage sludge was sampled and fractionated into four fractions: (1) slime, (2) loosely bound extracellular polymeric substances (EPS) (LB-EPS), (3) tightly bound EPS (TB-EPS), and (4) pellet. The results show that proteins (PN) and polysaccharides (PS) were mainly distributed in the TB-EPS and pellet fractions (75.1%), fewer in the slime and LB-EPS fractions. The sludge dewaterability was improved during anaerobic digestion, and the normalized CST correlated with PN, PS, and MW in the LB-EPS fraction. The results suggest that the size exclusion chromatography (SEC) technique could be an effective method to be potentially applied as an indicator to sludge dewaterability. Experimental Research on Treatment of Housing Estate Wastewater by Non-Residual Sludge Hydrolytic Acidification Process HONG-JUN HAN, CHUN-YAN MA and BING WANG ABSTRACT: With the increasing of the housing estate sewage quantity, the quantity of residual sludge was increasing at the same time. The proportion of investment and operation cost used for treatment of residual sludge was higher in total investment and operation cost. That brought some difficulties in treatment of housing estate sewage. In this paper, the non-residual sludge hydrolytic acidification process was taken to treat housing estate sewage. This cycle system was composed of medium-temperature anaerobic acidification reactor and aerobic biosystem. Aerobic and anaerobic microorganism died and could be degraded continuously through a variable anaerobic-aerobic process. Tests showed that operation of acidification reactor would have better effect under the condition of temperature 34°C, HRT 1.5 day, PH 5.5–6.0 and residual sludge could be decreased or zero emission. In this paper design and effective control of acidification reactor were also discussed. Investigation into the Fate of a Metabolic Uncoupler, 2,6-dichlorophenol in the Sequence Batch Reactor System YU TIAN, ZHIPENG LI, JUN ZHANG and DI WU ABSTRACT: The fate of a metabolic uncoupler, 2,6-dichlorophenol (2,6-DCP) was investigated in the sequence batch reactor systems for 3 months by determination of 2,6-DCP in the dissolved and particulate phases. Two sequence batch reactors were used: one system was used as a control, while the other received 2,6-DCP concentrations equal to 20 mgL-1. The results revealed that 70 ± 5% of 2,6-DCP was still in the final effluent during the day of 1–40. During the next days (days 40–70), 10 ± 4% was biodegraded with the adsorption fraction increasing from 25 ± 5% of day 40 to 50 ± 2% of day 70, while the effluent part decreasing from 65 ± 4% to 40 ± 3%. Up to the end of the experiment (days 70–90), 20 ± 2% of 2,6-DCP was biodegraded, 35 ± 2% was removed via the effluent, while 45 ± 3% was removed by the activated sludge. The addition of 2,6-DCP initially deteriorated the removal of biological nutrient (days 1–40). After acclimatization of biomass, the biological nutrient removal was recovered and 2,6-DCP could reduce sludge generation by about 5% (days 70–90). Mechanochemical and Biological Degradation of PCB in Contaminated Marine Sediments G. CAGNETTA, G. INTINI, L. LIBERTI1 M. NOTARNICOLA, L. SPINOSA and P. STELLACCI ABSTRACT: Large amounts (megatons) of marine sediments, partly contaminated by toxic recalcitrant organics like polychlorobyphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) and as well as by heavy metals and other inorganic pollutants, result from dredging operations at industrial harbors worldwide. In order to avoid the unsustainable burden of sanitary land filling of this huge amount of special/hazardous waste and to find out technical and cost effective methods for its detoxification and eventual reuse as building material for new marine embankment, an R&D project has been undertaken. The project is based on two complementary advanced technologies: short mechanochemical (MC) pretreatment, wherein chemical reactions are activated at nano-particle level by collisions with milling bodies in special high energy milling devices, followed by biological treatment (B) with purposely isolated aerobic bacteria like Burkholderia xenovorans. The experimental results aimed at determining the kinetics and the overall technical efficiency of the MC+B treatment of artificially contaminated marine sediments from the harbor of Taranto (S.Italy) indicated that, in the best operating conditions, PCB degradation may be achieved in very effective (~50%) and fast (<8 d) manner. Moisture Removal Mechanism of Sludge Conditioning by Freeze-Thaw Process HSING-SHANG LEE, JIANN-LONG CHEN, KUNG-YUH CHIANG, CHIH-CHAO WU and CHENG-LIANG CHEN ABSTRACT: The purpose of this study is to investigate the effects of sludge floc size and solids content on freeze-thaw conditioning and to enhance our understanding of the freeze-thaw conditioning mechanism. Digested activated sludge and an unidirectional freezing apparatus were used to perform the experiment. The results indicated that if sludges of small floc size was frozen at low speed, i.e, 10 mm/h, floc migration and aggregation occurred with the formation of ice front causing dehydration. This resulted in increasing floc compactness and narrowing the particle size distribution (PSD). For sludges composed of large floc, the floc were easily destroyed by the migrating ice front resulting in a smaller mean floc diameter and PSD than sludges composed of small floc. At low freezing speed, development of ice front for sludge with high solid concentration is slower than that of sludge with low solid concentration. When high freezing speed was employed to freeze sludge, floc destruction by ice front was more obvious, and the compactness of particle layer was lower than that caused by low freezing speed. Furthermore, under high freezing speed sludge with high solid concentration was easily entrapped by the ice crystal, and floc diameter was increased. However, gross migration of sludge was not found under this condition. Based on the experimental results, a modified model for the sludge freeze conditioning is proposed with the consideration of the effect of floc size and solids concentration. In addition, pretreatment to increase the solid concentration and decrease floc size before freeze-thaw conditioning are recommended to enhance the efficiency of this technique. On the Necessity of Sludge Conditioning with Non-organic Polymer: AOP Approach Y.Q. ZHAO, C. KEOGH and MAHA A. TONY ABSTRACT: Organic polymers have long been used as sludge conditioners to improve its dewaterability in sludge management practice. Although polymers can bring about a great dewatering performance of the sludge, their potential health related risk remains unknown regarding their residual in dewatered sludge cakes in the environment when the sludge is finally disposed as landfill especially in long term point of view. For this regard, as an initiative action, Fenton (Fe2+/H2O2) and its related reagents were tested in this study as a potential alternative an alum sludge conditioners for the purpose of eliminating the perceived long term risk associated with polymer residual in the environment. Optimized Coagulation on a Municipal Wastewater Treatment: Competitive and Synergetic Effect Among Different Pollutants DONGSHENG WANG, XUZHENG XU, ZEQUN LIU, XUELIN GU and GUOREN XU ABSTRACT: Iron(II) shows an increasingly attractive option among the main metal salts available for phosphorous removal by chemical precipitation. But other anions in the changing wastewater may compete with phosphorous for iron(II) also. Meanwhile, in the absence of oxygen, the iron(II) will not be oxidized and produce a very fine precipitate with phosphorous which is difficult to settle down easily. A case study towards an optimized coagulation system in a municipal WWT plant was therefore carried out to illustrate the competitive and synergetic effect during iron(II) coagulation. The results showed that FeSO4 can effectively reduce the dissolved total phosphorus (DTP) and sulfide (S2-), but total phosphorus (TP) is not reduced. Alum and polyaluminum chloride (PACl) could act as the coagulant aid to develop an effective coagulation process with the emphasis of phosphorus removal from wastewater. Ultrasonic lysis of Biological Sludge: A Three-stage Process G. ZHANG, P. ZHANG, X. KANG and F. GAO ABSTRACT: Ultrasounds have been known very effective for biological sludge disintegration, which can be used as a pretreatment method prior anaerobic digestion or sludge minimization. This paper is a preliminary investigation of the involution of sludge matrix during sonication. The sludge was treated with 0.8 W/ml ultrasounds at 20 kHz and the changes of the sludge size, supernatant chemical oxygen demand (SCOD), supernatant protein, nitrogen, phosphate, protein, and polysaccharides during sonication were recorded. The results showed that ultrasonic sludge disintegration could be treated as a three-stages process. The first stage lasted around 5minutes; during which the macro-flocs were destroyed, and the entrapped matters and free-water were released. The second stage lasted 10–15 minutes; during which the micro-flocs were destroyed, the extracellular polymer substances (EPS) were dissolved, the bacteria were disinfected, and the capillary water was released. The primary particulates dominated the last stage; and their small size prevented complete disintegration. As a result, the increase of supernatant organics showed a saturation effect.
CONTENTS (October 2009, Volume 6/Number 4) Editorial Continuation of Selected Papers Presented During the IWA-Sludge Conference Held in P. BRENT DUNCAN Research Sludge Disposal and Reuse as Resource Experiment of Gatifloxacin Adsorption by Sludge Activated Carbon OHONG YAO, ZEYU LV, YANMEI ZHOU and BO ZHANG Impacts of Pre-sun-drying on Sewage Sludge Compost J.L. ZOU, W.G. LI, K. WANG, J. DING and J. ZHANG K. Y. CHIANG, P. H. CHOU, K. L. CHIEN, J. L. CHEN and C. C. WU Sludge Treatment by O3/H2O2 and Carbon Source Recovery Y. X. ZHAO, J. YIN, H.L. YU, B.J. JIANG, J.H.WANG and S.K. JIANG Study on Hydrolysis and Acidification of Primary Sludge J. LI, J. REN, Y. P. GAN, J. ZHOU, S. ZHANG and Z. B. LI The Adsorption of Dyes in Water by using Modified Sludge YAO HONG, SHUI YUANMIN and ZHOU YANMEI ARTICLE ABSTRACTS (October 2009, Volume 6/Number 4) Experiment of Gatifloxacin Adsorption by Sludge Activated Carbon HONG YAO, ZEYU LV, YANMEI ZHOU and BO ZHANG ABSTRACT: In this paper, sludge activated carbon was made from two kinds of sludge by physical-chemical methods. The sludge was taken from the Gaobeidian municipal wastewater treatment plant in Impacts of Pre-sun-drying on Sewage Sludge Compost J.L. ZOU, W.G. LI, K. WANG, J. DING and J. ZHANG ABSTRACT: The aim of this study was to analyze the impacts of pre-sun-drying on sewage sludge compost. Comparative analysis was focused on the following parameters: moisture content (MC), pH value, total organic carbon (TOC), volatile solids (VS), water soluble total nitrogen (WSTN), ammonia nitrogen (AN), and dehydrogenase activity (DA). The results show that: the sun-drying process can quickly reduce initial moisture content from 82% to 77.7%. But the initial TOC and VS decreased from 356 g/kg and 59% to 326 g/kg and 50%, and the initial WSTN content was also decrease from 3.5 g/kg to 1.9 g/kg. As compost proceeded, the lower moisture content had slowed down the dehydrogenase activity (with an average of 271 mgTF/(g×h) vs. 199 mgTF/(g×h)) . And pH value reached a maximum of 9.35 (non-drying) and 8.79 (air-drying) respectively, which had something to do with the more NH3-N (12.2 g/kg vs. 4.4 g/kg) formed in the non-drying compost of the thermophilic phase. K. Y. CHIANG, P. H. CHOU, K. L. CHIEN, J. L. CHEN and C. C. WU ABSTRACT: Novel lightweight bricks have been produced by sintering mixes of dried water treatment plant sludge and agricultural waste. Samples containing up to 40 weight percent rice husk have been sintered using a heating schedule that allowed effective organic burn-out. Rice husk addition increased the porosity of sintered samples and higher sintering temperatures increased compressive strengths. Materials containing 40 weight percent rice husk that were sintered at 1100°C produced low bulk density and relatively high strength materials that were compliant with relevant Taiwan standards for use as lightweight bricks. This research was also evaluated the environmental safety of sintered products by the toxic characteristic leaching procedure (TCLP) concentration. The results indicated that TCLP concentrations of Cu, Zn, Cr, Cd, and Pb in the sintered products were lower than regulation thresholds. Sludge Treatment by O3/H2O2 and Carbon Source Recovery Y. X. ZHAO, J. YIN, H. L. YU, B. J. JIANG and S. K. JIANG ABSTRACT: Proper disposal of excess sludge has become a tough problem faced by most of wastewater treatment plants. In order to solve this problem, an advanced sludge treatment process combining hydrogen peroxide and ozone was proposed. The impacts of pH value, ratio of hydrogen peroxide to ozone and the original sludge concentration were investigated. As a result, the combination of hydrogen peroxide and ozone process was efficient for sludge disintegration. The optimum molar ratio of hydrogen peroxide to ozone was 1.2 and the pH value was 6. The increase of sludge initial concentration was beneficial for sludge disintegration. The ideal initial concentration of sludge was 9900 mg/L ~ 19600 mg/L. In addition, experimental results also proved that the hydrolysis of sludge could be used as carbon source for nitrogen removal. The average denitrification rate in sludge solution was 2.08 mgNO3-N/g MLSS·h which was 78% of methanol. Study on Hydrolysis and Acidification of Primary Sludge J. LI, J. REN, Y. P. GAN, J. ZHOU, S. ZHANG and Z. B. LI ABSTRACT: The phenomenon of carbon resource limited is a common problem in the municipal wastewater. In this study, primary sludge which come from primary sediment is been use for generating carbon resource by anaerobic hydrolysis acidification process. In the condition of temperature is 35°C, HRT = 28h and SRT = 3d, r(SCOD) and r(VFA) of effluents reach the peak value at 975.8 mg/L and 516.4 mg/L during the operate time. When the alkalinity is 725 mg/L and pH is 7.12, hydrolysis acidification process can keep the stable state of hydrolysis acidification efficiency. Appropriate alkalinity and pH value are the key parameters of hydrolysis acidification process for stabile operation. When the hydrolysis acidification process is fluctuated, the changes of r(SCOD) and VFA are previous to the alkalinity and pH value. |
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