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Evaluation of the Pozzolanic Activity of Sewage Sludge Ash  [PDF]
M. A. Tantawy,A. M. El-Roudi,Elham M. Abdalla,M. A. Abdelzaher
ISRN Chemical Engineering , 2012, DOI: 10.5402/2012/487037
Abstract: Raw sewage sludge was characterized by XRD, FTIR, SEM, and TGA techniques and incinerated in temperature range 650–950°C for 2?h. The effect of incineration temperature on the microstructure and pozzolanic activity of the resultant ash was investigated by techniques mentioned above as well as Chapelle test. It was concluded that incineration of sewage sludge affects the microstructure and pozzolanic activity of the resultant ash. During incineration at temperatures lower than 800°C, amorphous silica captures fixed carbon resulting from incomplete combustion conditions whereas at higher temperatures crystallization of amorphous silica was enhanced. Hydration products formed from hydrothermal treatment of silica fume with lime is amorphous whereas that of sewage sludge ash is fibrous. Hence, incineration of sewage sludge ash must be optimized at 800°C to preserve the pozzolanic activity of the resultant ash. 1. Introduction Sewage is the collection of wastewater effluents from domestic, hospital, commercial, industrial establishments, and rain water. The objective of sewage treatment is to produce treated sewage water and sewage sludge suitable for safe discharge into the environment or reuse [1]. The most common treatment options for sewage sludge include anaerobic digestion, aerobic digestion, and composting. Choice of the treatment method depends on the amount of sludge and other site-specific conditions [2]. Sewage sludge tends to accumulate heavy metals existing in the wastewater. The composition of sewage sludge and its content of heavy metals vary widely depending on the sludge origins and treatment options [3]. In past decades, sewage sludge was primarily disposed to landfills and seawaters [4]. Space limitations on existing landfills and increasing environmental concerns such as groundwater pollution from landfill leachate, odor emission and soil contamination have prompted the investigation of alternative disposal routes [5]. Sewage sludge has been used in agriculture as fertilizer and soil amendment [6]. However heavy metals such as Zn, Cu, Ni, Cd, Pb, Hg, and Cr are principal elements restricting the use of sludge for agricultural purposes [3]. The solidification/stabilization of sewage sludge in cementitious matrix has been evaluated [7]. Sewage sludge adversely affects durability of concrete, mainly due to the organic material which retards setting and heavy metals which interfere with the hardening reactions [8]. Hence, sewage sludge addition in concrete was limited to 10?wt.% and the solidified concrete was recommended for use in certain
The Effect of Lime Stabilization on the Microbiological Quality of Sewage Sludge
B Bina, H Movahedian, I Kord
Iranian Journal of Environmental Health Science & Engineering , 2004,
Abstract: Agricultural utilization of wastewater sludge is practiced in many parts of the world. Sludge may contain a variety of pathogenic microorganisms, which can spread diseases if there is human exposure to the sludge. Therefore, sludge must be treated before disposal and reuse. In this study the effect of liming on the microbiological quality of urban liquid raw sludge in Isfahan Wastewater Treatment Plant (IWTP) was investigated. Sludge samples were taken from IWTP, and the initial concentrations of total solids, volatile solids, total coliform, fecal coliform, Salmonella and ova of parasites were determined. Then adding lime to increase the pH of sludge to 11 and 12 and the effect of liming on the parameters was carried out after 2, 24, 72 and 120 hours. Salmonella was inactivated completely in treated sludge after two hours. The removal of up to 99% of fecal coliform was obtained for two ranges of pH. However, reduction of ova of parasites at pH 11 and 12 after five days were found only 56% and 83.8% respectively. Sludge treated with lime meets USA Environmental Protection Agency (EPA) standards regarding Class B and Class A after 2 and 24 hours respectively. At pH higher than 11 and 12 treated sludge with lime meets vector attraction reduction requirements after two hours. However, at a pH higher than 11 and 12 treated sludge with lime does not meet the guideline for pathogen reduction of class a regarding eggs of parasites.
The influence of aerobic sludge retention time on anaerobic co-digestion of dyeing and printing wastewater and sewage sludge
J Wang, Z Zhang, Z Zhang, P Zheng, C Li
African Journal of Biotechnology , 2007,
Abstract: Two pilot-scale activated sludge systems comprising anaerobic baffled reactor (ABR) and aerobic plug flow reactor (PFR) were operated aiming to minimize excess sludge output of the activated sludge process through coupled alkaline hydrolysis and anaerobic digestion. Variations in the effluent total chemical oxygen demand (TCOD) and NH4 +-N concentration proved that the process not only could minimize excess sludge production but also guarantee the effluent TCOD well below the discharging limit (150 mg/l) if the inverse ratio of the aerobic sludge recirculation to anaerobic reactor did not exceed 60% for system A with 10 d aerobic sludge retention time (SRT) and 40% for system B (SRT was 25 d). The sludge activity at aerobic SRT of 25 d was evidently lower than aerobic SRT of 10 d. Those differences of sludge characteristics affected the inverse sludge ratio obviously. Aerobic bacteria after internal and external decay were converted to anoxic or anaerobic biomass. The distinct differences in sludge yield of aerobic and anaerobic/anoxic processes could explain how aerobic SRT decided excess sludge activity which consequently affected anaerobic codigestion of printing and dyeing wastewater and sewage sludge.
Changes of Cu, Zn, and Ni chemical speciation in sewage sludge co-composted with sodium sulfide and lime
WANG Xuejiang,CHEN Ling,XIA Siqing,ZHAO Jianfu,
WANG Xuejiang
,CHEN Ling,XIA Siqing,ZHAO Jianfu

环境科学学报(英文版) , 2008,
Abstract: A batch composting study was performed to evaluate the feasibility of co-composting sewage sludge with sodium sulfide and lime (SSL) mixture (Na2S/CaO= 1:1), aiming at reducing the availability of heavy metals in the sludge compost. Sewage sludge with sawdust as a bulking agent was amended with SSL at 3% (w/w, dw), and composted for 15 d in laboratory batch reactors. The four stages of the Tessier sequential extraction method was employed to investigate changes in heavy metal fractions of Cu, Zn, and Ni in sewage sludge composted with SSL. For all the three metals, the mobile fractions, such as, exchangeable and carbonate bound were mainly transformed into low availability fractions (organic matter and sulfide, Fe-Mn oxides bound and residual forms), and the addition of SSL enhanced this transformation. Therefore, SSL is a suitable material to co-compost with sewage sludge to reduce the availability of heavy metals. According to the cabbage seed germination test, a SSL amendment of ≤3% (w/w, dw) is recommended to co-compost with sewage sludge.
Kinetics Study of Sewage Sludge Treatment by an Aerobic Digestion  [PDF]
Abdurahman H. Nour,Azhary H. Nour,A.P.S. Vissaliny,A.P.V. Rajaletchumy
Journal of Applied Sciences , 2010,
Abstract: In this study, a 50 L laboratory scaled Membrane Anaerobic System (MAS) combining ultrafiltration (UF) membrane with anaerobic reactor was used to treat raw sewage sludge. Six steady states were attained as a part of a kinetic study. The three kinetic models (Monod, Contois and Chen and Hashimoto) were successfully fitted. The results of all six steady states were successfully fitted above 98% by Monod, Contois and Chen and Hashimoto. Contois model appeared to be the best at 99.7%. The microbial kinetic constants were Y = 0.74 g VSS g-1 COD and b = 0.20 day-1. The minimum solids retention time, θcmin obtained from the three kinetic models ranged from 5-16.9 days. The k values were in the range of 0.350-0.519 g COD g-1 VSS day and μmax values were between 0.259 and 0.384 day-1. The Solids Retention Time (SRT) decreased from 1250 days to 16.1 days. The methane gas yield was between 0.19 to 0.54 L g-1 COD day-1 when the organic loading rate increased from 0.1 kg COD/m3/day to 10 kg COD/m3/day. The COD removal efficiency was 96.5-99% with HRT of 7.8 days. And the rage of mixed liquor suspended solids was from 12760 to 21800 mg L-1.
Journal of Research in Medical Sciences , 2002,
Abstract: Introduction. Sludge production from municipal wastewater treatment plants should have quality standards before disposal in to the environment. Environmental specialists classified sewage sludge as a hazardous waste because of high organic compounds and pathogenic microorganisms. They belive that sewage should be stabilized before disposal and so composting of sewage sludge is an effective and economical method to stabilize. Sewage sludge compost could be used to improve soil structure and enrich the soil with nutrients. Methods. To evaluate the optimum conditions of aerobic compost, the mixture of dewatered sewage sludge from Isfahan municipal waste water treatment plant and sawdust as bulking agent were used. Pilot scale study were performed in Isfahan municipal waste water treatment plant. To perform this research project, the dewatered sewage sludge with humidity between 78 to 82 percent were mixed with sawdust. Turning over method of the piles with one week interval were applied to aerate the mixture. Temperature of the piles were monitored at different depths daily. Other parameters such as N, G, organic matters and pH were determined weekly. Total and fecal coli form, and salmonella were determined at the beginning and end of the composting process, also heavy metals were measured at the same time. Results. The results of this study showed that after days, temperature of the mixture reached up to 55 G, and were stabled for 15 days. Humidity, organic matter, organic carbon and GIN ratio of the mixture decreased over the period of the study, due to increasing the temperature. Also organic matter and humidity mainly decreased in thermofilic phase. The number of total and fecal coliform and also salmonella decreased to A class standards of US.EPA at the end of the operation. Discussion. The results of the study also showed that, this type of composting method is reliable, and simple to schedule, with high flexibility and low odor production. Organic compounds and pathogenic microorganisms reduced and EPA standards were reached during this project.
Small-Sized Non-Sludge-Discharged Sewage Treatment and Reuse System

Chen Xueyi,

环境科学 , 1995,
Abstract: A small-sized sewage treatment and reuse system without sludge discharge has been developed,based on a process consisting of two stages of contact anaerobic filters, two stages of contact aero bio filters, a slow sand filter and a fast sand filter. Generally, a domestic sewage can be treated through this system to give a satisfactory effluent, with a BOD removal of 91.7%, a COD removal of 88. 9%, a SS removal of 91.1%, and a total P removal of up to 43.5%.
Degradation of organic contaminants with biological aerobic fermentation in sewage sludge dewatering and its influencing factors

YU Jie,ZHENG Guodi,GAO Ding,LIU Hongtao,CHEN Tongbin,

生态学报 , 2012,
Abstract: Concentrations of the organic contaminants in sewage sludge dewatering of several Chinese cities were analyzed,and pointed out the concentration of PAHs was 1.156—34.940mg/kg,PCBs content was 0—115.730mg/kg;PCDD/Fs concentration was 9.530—22.900ngTEQ · g-1dm,NP concentration was 177 mg/kg.This paper demonstrated that the organic contaminants in sludge can be degraded with the aerobic biological treatment technology,and the environment risk of the organic contaminants in sewage sludge can be reduced to realize the safety and environmental protection of land use.Meanwhile,by optimizing sludge biological aerobic fermentation control conditions: C/N in the range of 25 ∶ 1 to 40 ∶ 1,a temperature of 30 to 55℃,the oxygen concentration is 5%—15%,forced ventilation control in 1.5—2.0m3 · min-1 · t-1(dried mud),pH6—9,mixing water rate is 50%—65%,the environmental risk of sewage sludge land application can significantly be reduced.The resource utilization of the sludge to bring about two pollution problems can also be avoided.
Simultaneous Phosphorus and Nitrogen Removal of Domestic Sewage with Aerobic Granular Sludge SBR

LU Shan,JI Min,WANG Jing-feng,WEI Yan-jie,

环境科学 , 2007,
Abstract: By seeding aerobic granular sludge cultivated from artificial wastewater, an anaerobic/aerobic SBR was applied to treat domestic sewage of high COD, TN and SS. The stability of granular sludge and the removal of organic pollutants, nitrogen and phosphorus of domestic sewage were investigated. After one month incubation, the reactor had good pollutant removal performances and run stably. The ratio of granular sludge to total suspended solids was over 68% all along. The sludge concentration was 5 000 - 6 000 mg/L and SVI value was 20 35 mL/g. After three months operation, most of the granules were over 1.25 mm instead of 0.6 - 0.9 mm in the beginning. During the stable operation phase of the granular sludge SBR, the average removal effieieneies of COD, TOC, phosphate, ammonium nitrogen, total nitrogen, SS were 83.04 %, 70.41%, 94.30 %, 86.51%, 41.82 % and 85.89 %, respectively. Analysis of the pollutant removal in typical cycle showed that the granular sludge had good simultaneous phosphorus and nitrogen removal performance.
Microbiological and physicochemical treatments applied to metallurgic industry aiming water reuse
Bello, Antonio Roberto Crystal;Angelis, Dejanira de Franceschi de;Domingos, Roberto Naves;
Brazilian Archives of Biology and Technology , 2008, DOI: 10.1590/S1516-89132008000200020
Abstract: a study was conducted on the reuse of the water in a system composed of a sewage treatment plant (stp) using prolonged aeration with activated sludge and a compact water treatment plant (cwtp) in a metallurgic industry. the processes for obtaining the water for reuse were microbiological and physicochemical. the domestic sewage was then pumped to the stp, where biological flocks were formed and clarified water was obtained. the efficiency of the microbiological process in the stp was evaluated for removal of biochemical oxygen demand (bod), chemical oxygen demand (cod) and sedimentary solids (ss). the efficiency of physicochemical processes for clarifying the water and disinfection was evaluated through analysis of ph, turbidity, color, aerobic heterotrophic bacterial count, free chlorine, hardness, alkalinity, chlorides, sulfates and dissolved total solids (dts). in the reuse of the water, acute toxicity for the microcrustaceans daphnia similis was also evaluated.
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