Innovative anaerobic upflow sludge blanket filtration combined bioreactor for nitrogen removal from municipal wastewater

In this research, a novel laboratory scale anaerobic/upflow sludge blanket filtration combined bioreactor was designed and operated to improve the efficiency of the upflow sludge blanket filtration process for the simultaneous removal of phosphorus and nitrogen from wastewater. The anaerobic/upflow sludge blanket filtration technique was developed by adding an anaerobic reactor to its influent and operated by varying the main process parameters in order to gain the optimum conditions. The results showed that biological removal efficiency of nitrogen and preservation of sludge blanket strongly depend on wastewater characteristics, hydraulic retention time, sludge age and process controlling parameters. The combined bioreactor performed a total nitrogen removal efficiency of 96.6% with the sludge age of 25 days, total hydraulic retention time of 24 h and optimum "chemical oxygen demand/nitrogen/phosphorus" ratio of 100/5/1. This ratio also improved the compaction quality of sludge blanket in the upflow sludge blanket filtration clarifier. The average specific nitrification and denitrification rates occurred during the process can be expressed as 4.43 mg NOx-N produced/g VSS.d and 5.50 mg NOx-N removed/g VSS.d at the optimum ratio, respectively. To avoid sludge rising due to denitrification process, the optimum total hydraulic retention time of 16 to 24 h was achieved based on the effluent quality. This study suggested that the anaerobic/upflow sludge blanket filtration bioreactor at the optimum operational conditions can be an effective process for removal of nutrients from municipal wastewater

Evaluation of stability parameters in in-vessel composting of municipal solid waste

Composting is a reliable technology for production of stabilized organic matter that is suitable for agriculture, but this process should be carefully monitored with appropriate indices. Quality of compost is important from maturity and stability viewpoint, but in most compost factories proper attention is not paid to it. This study was designed to evaluate the stability indices in municipal solid waste composting, for selecting the best index in quality monitoring of the wastes. Processed and shredded municipal solid waste from Isfahan compost plant was used as raw material in an in-vessel composting process. A cylindrical reactor with 1 m height and 50 cm diameter made of Pyrex glass was designed. Air was supplied at a specifically flow rate 0.2 L/min.kg to maintain aerobic condition. NH[4][+]/ NO[3] ratio, dehydrogenase enzyme activity [DA], pH, oxidation reduction potential [ORP or Eh] and specific oxygen uptake rate [SOUR] were used as stability indices. These parameters were measured during 40 days of composting process. Changes in these parameters during this period were surveyed and analyzed. Statistical analysis was carried out to choose best of them. Results showed that among the indices, SOUR can show the different stages of microbial decomposition and a numerical value for compost stability also SOUR value less than 2 mg O[2]/gVS.h can show the full stability of compost

Performance of moving bed biofilm reactors for biological nitrogen compounds removal from wastewater by partial nitrification-denitrification process

In this research, the continuously operated laboratory scale Kaldnes [k1] moving bed biofilm reactors [MBBRs] under partial nitrification-denitrification process were used for treatment of synthetic wastewater containing ammonium and glucose. The Anoxic and Aerobic reactors were filled to 40 and 50% [v/v] to attach and retain biomass with k1 biofilm carriers, respectively. The favorite internal recycle ratio and hydraulic residence time [HRT] to eliminate nitrogen compounds were 300% of inflow rate and 20 hours, respectively. Optimal dissolved oxygen [DO] was 1-1.5 mg/L in the aerobic reactor. No sludge was returned into the system and only an internal recycling was performed from aerobic to anoxic reactor. The results showed that the maximum and average specific nitrification rate [SNR] in the aerobic reactor were 49.4 and 16.6 g NOx-N/KgVSS.day, respectively and the maximum and average specific denitrification rate [SDNR] as 156.8 and 40.1gNOx-N/KgVSS.day in the anoxic reactor, respectively. The results also showed that it is possible to reach a stable partial nitrification with high ratio of NO2-N/NOx-N [80% to 85%] during high load ammonium and low DO concentration [<1.5 mg/L] in the aerobic reactor. During optimum conditions, the average removal efficiency of total nitrogen [TN], ammonia and soluble organic carbon [SCOD] occurred as 98.23%, 99.75% and 99.4%, respectively. This study showed that the partial nitrification/denitrification process in the moving bed biofilm reactors system has an acceptable performance for treatment of wastewater with high load of organic carbon and organic nitrogen compounds

[Survey on possibility of disinfection of Isfahan north wastewater treatment plant effluent by low and medium pressure ultraviolet systems in pilot scale]

Today, due to health, environmental and economical problems, of chlorine application, UV radiation is better option than chlorine for disinfection of effluent. The aim of this study was disinfection of secondary effluent with UV radiation. Two types of UV disinfection system including low pressure [LP] and medium pressure [MP] was used to disinfection of Isfahan North Wastewater Treatment Plant [INWWTP] effluent without pretreatment. Single and combined lamps were operated to evaluate the removal of total and fecal coliforms [TC and FC], and fecal streptococcus [FS]. TSS, iron, hardness, UV absorption and transmittance were analyzed in order to observe the fouling of the quartz sleeves. After using LP lamp with dose of 161 mws/cm[2], TC and FC content was declined to standard level [1000 TC, and 400 FC/100ml]. In addition, disinfection with MP lamp was led to FS content of 400 MPN/100 mL. Combination of LP and MP, with dose of 460 mws/cm[2] could be met the environmental requirements of TC and FC, and the FS count was reached to 400 MPN/100 mL with dose of 237 mws/cm[2]. Maximum photo-reactivation percentage of coliforms after LP and MP lamps were appeared 15 and 3 percent respectively, while it was not observed for FS. High fluctuation in secondary effluent quality of INWWTP mainly TSS concentration was caused to decline of the UVT value. Therefore, disinfection of effluent by LP, MP and even combined both systems are not applicable in conventional UV dose. Hence, using advanced process unit before UV disinfection system is necessary for removal of TSS

Spatial analysis of three agrichemicals in groundwater of isfahan using GS[+]

The purpose of this study was to undertake a spatial analysis of total organic carbon, electrical conductivity and nitrate, in order to produce a pollution dispersion and prediction map for the investigated area in the province of Isfahan in Iran. The groundwater samples were collected from a zone as a pilot study area of 80 km[2], including 25 water wells, based on the criteria of vulnerability assessment projects, that is, about one well per 3 km[2], during four seasons in 2008-09. In order to make any inferences about the areas that did not have well data, a statistical relationship between explanatory total organic carbon, electrical conductivity and nitrate variables related to well coordination was developed. The probability of the presence of elevated levels of the three compounds in the groundwater was predicted using the best-fit variogram model. According to spatial analysis, the highest R[2]=0.789 achieved was related to electrical conductivity and followed the exponential model with 0.266 for NO[3] [spherical model] and 0.322 for total organic carbon [exponential model] in the spring 2009. This showed the high confidence level for electrical conductivity dataset and forecasted trends. The results of the spatial analysis demonstrated that the transfer trends of electrical conductivity in the groundwater resources followed the route of groundwater movement in all seasons. However, for nitrate and total organic carbon, a definite trend was not obtained and pollution dispersion depended on many parameters

Effectiveness of chitosan as natural coagulant aid in treating turbid waters

During the last decade, there has been a concern about the relation between aluminum residuals in treated water and Alzheimer disease, and more interest has been considered on the development of natural coagulants such as chitosan. Chitosan, a natural linear biopolyaminosaccharide, is obtained by alkaline deacetylation of chitin. The present study was aimed to investigate the effects of alum as coagulant in conjunction with chitosan as coagulant aid on the removal of turbidity, hardness and Escherichia coli from water. A conventional jar test apparatus was employed for the tests. The optimum pH was observed between 7 to 7.5 for all turbidities. The optimum doses of alum and chitosan when used in conjunction, were 10mg/L and 1mg/L, 5mg/L and 0.5mg/L, and 5mg/L and 0.5mg/L in low, medium and high turbidities, respectively. Turbidity removal efficiency was resulted between%74.3 to%98.2 by alum in conjunction with chitosan. Residual Al[+3] in treated water was less than 0.2 mg/L, meeting the international guidelines. The results showed that turbidity decrease provided also a primary Escherichia coli reduction of 2-4 log units within the first 1 to 2 hr of treatment. Hardness removal efficiency decreased when the total hardness increased from 102 to 476mg/L as CaCO3. At low initial turbidity, chitosan showed marginally better performance on hardness, especially at the ranges of 100 to 210 mg/L as CaCO3. In conclusion, coagulant aid showed a useful method for coagulation process. By using natural coagulants, considerable savings in chemicals and sludge handling cost may be achieved

survey of polycyclic aromatic hydrocarbons and heavy metals in ambient air of Isfahan, 2003

During the past two decades, the determination of heavy metals and Polycyclic Aromatic Hydrocarbons [PAH[5]] in the ambient air of industrialized cities has gained great importance. Heavy metals and PAH[5] in flue gas have received considerable attention in recent years due to their mutagenic or carcinogenic properties. PAH[5], are products of incomplete combustion of carbonaceous compounds at high temperatures The sources of PAH[5], into the atmosphere include: waste incineration, exhaust emission of petrol and diesel engine automobiles power plants, and residential heating systems. Heavy metals are released into the ambient air from the same sources as those earlier mentioned for PAH[5]. The present study is carried out to investigate the influence of the quantity of heavy metals on PAH[5] formation in ambient air. Heavy metals encourage not only absorption of PAH[5] but also catalyze PAH[5] formation. In this study, air particulates were collected on glass fiber filters using a high-volume air sampler. Flow rate and sampling period were 0.5 m[3]/min and 24 hrs. respectively. Each filter was exactly cut into equal pieces. One piece was digested with HNO[3] as well as H[2]O[2] and used for determination of heavy metals. Another piece was extracted with DCM Using Soxhlet method. The latter was used for the determination of PAH [5]. The concentrations of heavy metals [Cr, Cd, Cu. Pb, and Zn] were measured by using Perkin-Elmer atomic absorption spectrometer PAH[5]. The concentration of PAH[5] was measured by a PU4400 gas chromatograph equipped with RD detector. The concentrations of PAH[5] and heavy metals were determined in different seasons, The results showed that the concentration of PAH[5] was minimum in the weekend and holidays, but maximum in winter. The relationship between ambient air concentrations of PAH[5] and heavy metals was investigated and an excellent agreement was found. The general trend of variations in concentratioll of heavy metals were found very similar to PAH[5] therefore it could be concluded that the source of pollution was same for both the pollutants

Effect of influent COD/N ratio on nitrification rate in a bench-scale biological reactor

Nitrification, the oxidation of ammonia tp nitrate catalyzed by bacteria, is a key part of global nitrogen cycling. In the first step of nitrification, chemolithoautotrophic ammonia oxidizers transform ammonia to nitrite, which is subsequently oxidized to nitrate by nitrite-oxidizing bacteria. This process can be affected by several factors. In this study the effect of influent COD/N ratio on nitrification rate in a bench-scale biological reactor was investigated. Experiments were carried out using synthetic wastewater. The initial ammonium concentration was 25 mg NH[4]-NL[-1]. The effect of COD/N ratio between 10.0l +/- 0.083 and 24.08 +/- 0.22 gCODgN[-1] on nitrification rate were investigated by varying the COD loading supplied to the reactor. From the results obtained in this study it is found to be in the range of 10.01 +/- 0.083 to 14.15 +/- 0.17 gCODgN[-1], there is a direct relationship between COD/N ratio and nitrification rate. However, more than 14.15 +/- 0.17 up to 24.08 +/- 0.22 gCODgN[-1] was found to exhibit an indirect relationship between the ratio and rate

relationship between polycyclic aromatic hydrocarbons and heavy metals in Isfahan city

During the past two decades, determination of heavy metals and Polycyclic Aromatic Hydrocarbons [PAH,] in the atmosphere of industrialized cities have gained great importance. Heavy metals arc toxic and polycyclic aromatic hydrocarbons are known as toxic, carcinogenic and mutagenic compounds. PAHs are products of incomplete combustion of carbonaceous compounds at high temperatures. The sources of PAHs into the atmosphere include: waste incineration, exhaust emissions of petrol and diesel engine automobiles, plant powers, and residential heating systems. Heavy metals are released into the atmosphere from the same sources as those earlier mentioned for PAHs In this study, air particulates were collected on glass fiber filters using a high-volume air sampler. Flow rate and sampling period were 0.5 m[3]/min and 12 hrs respectively. Each filter was exactly cut into equal pieces. One piece was digested with HNO3 as well as H2O2 and used for determination of heavy metals. Another piece was extracted with dichloromethane [DCM] using Soxhlet method. The latter was used for the determination of PAHs. The concentrations of heavy metals were measured using Perkin-Elmer atomic absorption spectrometer. The concentration of PAHs was measured by a PU4400 gas chromatograph equipped with Fill detector. The concentrations of PAHs and heavy metals were determined in different seasons. Lead and cadmium were higher than similar cities in Iran. The results showed that the concentration of PAHs was minimum in the weekends and holidays. But it was maximum in winter. The relationship between the atmospheric concentrations of PAHs and heavy metals was investigated and an excellent agreement was found. The determination of concentrations of PAHs by HPLC-GC was also investigated and the results were compared to those determined by CGC. An excellent agreement between the results of two techniques was also found. The general trend of variations in concentration of heavy metals was found very similar to PAHs, therefore, it could be concluded that the source of pollution was same for both the pollutants

study on relationship between the atmospheric quantity of heavy metals and PAHs in the city of Isfahan

Heavy metals are toxic and polycyclic aromatic hydrocarbons are known as toxic, carcinogenic and mutagenic compounds. To determine the concentration of PAHs and heavy metals in sample and the relationship between these two pollutants in the atmosphere of the city of Isfahan. In present study, air particulates were collected on glass fiber filters by using a high- volume air sampler. Flow rate and sampling period were 0.5m3/min and 12 hrs, respectively. Each filter was exactly cut into two equal pieces. One piece was digested with HNO3 and H2O2, and the second piece was extracted with DCM, using soxhlet method. The later was used for determination of PAHs. Determinations of heavy metals concentration were performed using a Perkin-Elmer atomic absorption spectrometer. The concentrations of PAHs were measured using a PU 4400 gas chromatograph equipped with a FID detector. The concentration of lead was higher than other metals [748.5 ng/m3] however; it was lower than the standard value [2000 ng/m3]. The extraction efficiency of PAHs with soxhlet method was 92-100 percent. The concentration of Benzo [ALPHA] pyrene, index of aromatic hydrocarbons, was 2.27 ng/m3. PAHs concentration in non-working days was lower than working days of a week. Correlation coefficient between PAHs and heavy metals was 0.9 [p<0.005]. The changing pattern of heavy metals and PAHs was closely similar. The concentrations of PAHs and heavy metals were determined in different samples. The relationship between the atmospheric concentrations of PAHs and heavy metals was investigated and an excellent agreement was found.

Comparison of the biological NH[3] removal characteristics of a three stage biofilter with a one stage biofilter

A three stage and a one-stage bench-scale biofilter with effective heights of 129 cm filled with same type of packing material were operated at different influent concentrations of ammonia in order to investigate their performance in treating waste gas streams. The columns contained a mixture of municipal compost inoculated with thickened municipal activated sludge as a base material and shredded hard plastic as a bulking agent in a 3:2 v/v ratio; the porosity, density and pH were 52%, 0.65 and 7.2 respectively. Microbial acclimation to ammonia was achieved by exposing the three stage biofilter to an average inlet loading rate of 2.15g-NH3/m3 h and the one-stage to an average inlet loading rate of 1.32 g NH3/m3 h and an empty bed residence time of 60 s, for 10 days and 17 days respectively. Under steady-state condition, maximum elimination capacity [EC] was 9.85 g-NH3/m3h at a loading rate of 9.86 g-NH3/m3h for three-stage biofilter and 8.08 g NH3/m3h at a loading rate of 8.13 g-NH3/m3h for one-stage biofilter. The average pressure drop across biofilters bed was determined 33.76 Pa/m1 in three-stage biofilter and 180.7 Pa/m1 in one-stage biofilter. The three stage biofilter showed superior performance and gained more elimination capacity, shorter acclimation time, longer operation in steady-state condition and less pressure drop than one-stage biofilter

Toxicity evaluation of wastewater treatment plant effluents using Daphnia magna

Toxicity evaluation is an important parameter in wastewater quality monitoring as it provides the complete response of test organisms to all compounds in wastewater. The water flea Daphnia magna straus is the most commonly used zooplankton in toxicological tests. The objective of this study was to evaluate the acute toxicity of effluents from different units of Isfahan Wastewater Treatment Plant [IWTP]. The samples were taken from four different physical and biological units. The acute toxicity tests were determined using Daphnia magna. The immobility of Daphnia was determined after 48h. Toxicity results showed that 48h-LCq and ATU values for raw wastewater were 30% [v/v] and 3.33, respectively. It was also found that LC50 values after 48 h for preliminary, primary, and secondary effluents were 32%, 52% and 85% [v/v], respectively. The ATU values for these effluents were 3.1, 1.9, and 1.8, correspondingly. The efficiency levels of preliminary, primary, and secondary units for removal of toxicity were found as 6%, 38.9% and 8%, in that order. Overall, the present investigation indicated that toxicity removal by up to 50% might be achieved in IWPT. Based on the obtained results and regarding the improvement of water quality standards, coupled with public expectations in Iran, it is necessary to consider more stringent water quality policies for regular monitoring and toxicity assessment

Biological removal of Ammonia from contaminated air streams using biofiltration system

Ammonia is a colorless, toxic, reactive and corrosive gas with a sharp odor. It is irritating to the skin, eyes, nose, throat, and lungs. Ammonia gas occurs in the environment naturally and is emitted by many industries and, therefore, its control is essential. Biofiltration is a new emerging technology that is being used as a control procedure. This study evaluates the use of a mixture of compost, sludge, and pieces of PVC as biofilter media to remove ammonia gas. The study investigates the effects of parameters such as inlet concentration, accumulation time, and depth of filter media to evaluate the removal efficiency. A laboratory scale biofilter column was built and operated to investigate the removal of ammonia from a waste gas stream. The findings indicate that for inlet concentrations of 236 ppm, and ammonia loading of less than 9.86 g-NH3/m3.h at empty bed residence time of 1 min, an ammonia removal efficiency of more than 99.9% was obtained. The acclimation period of the bacteria was 10 days. The average pressure drop during measurement was 4.44 mm H2O. The study also revealed that for concentration levels of 99, 211, and 236 ppmv, biofilter media depths of 40, 80, and 120 cm will be required, respectively. The results obtained in this study indicate that the biofiltration system composed of compost in the mixture of sludge and smashed polyvinyl chloride as biofilter media is an efficient method for the removal of ammonia from waste gas streams. It is also found that the optimum depth of biofilter media depends on the inlet concentration of ammonia

Effects of aeration rate and detention time on thermophilic aerobic digestion of mixed sludge and its dewaterability

Thermophilic aerobic digestion [TAD] is a possible alternative for rapid sludge degradation and producing Class A biosolids. Aeration rate and detention time are two of the important parameters in TAD processes due to rapidly growing thermophilic bacteria population, limited solubility of oxygen at high temperatures and the need to prevent cooling of TAD process. Also the current knowledge and understanding of dewatering TAD biosolids are limited and incompelet.The objectives of this study were to investigate the effects of various aeration rates and detention time on some characteristics of mixed sewage sludge. Four glass-cylindrical digesters with 7 liters of sludge in each, placed in a water bath and were operated at 55 ?C with the aeration rates of 2.14, 3.00, 3.86 and 4.71 volume of air per volume of sludge per hours. It was found the increase in aeration rate decreased the required detention time in order to meet the Class A sludge regulations to reduce vector attraction. The values of Oxidation-Reduction Potential [ORP] were changed from negative values to positiv ones and the values of pH were increased from around neutral to slightly basic, but this increases were occured at different detention times. TAD affected dewaterability of mixed sewage sludge and produced biosolids with higher specific resistance to filtration [lower dewaterability] than undigested sludge. Thermophically digested sludge has a good setteling behavior and air drying on sand bed

Influence of the antibiotic erythromycin on anaerobic treatment of a pharmaceutical wastewater

Background: the purpose of this study was to evaluate the influence of different concentrations of erythromycin on the anaerobic treatment of a synthetic pharmaceutical wastewater in an Anaerobic Sequencing Batch Reactor [ASBR]

Methods: a laboratory-scale ASBR was used to treat a synthetic substrate mixture representing pharmaceutical wastewater. The ASBR was operated with increasing organic loading rates until stable removal efficiencies were reached at a loading rate of 3 g COD L-1 d-1. At that point the reactor was exposed to low [1 mg/l] and subsequently, to high [200 mg/l] concentrations of the antibiotic erythromycin

Results: the effect of addition of erythromycin on the microbial community and the development of antibiotic resistance were evaluated based on overall reactor performance and using specific methanogenic activity [SMA] tests. It was found that the addition of erythromycin resulted in a reduction of biogas production and COD removal efficiency by 5 to 10%. As expected based on the reactor performance, biogas. production in SMA tests using the synthetic substrate mixture was only slightly affected by the presence of erythromycin. When sludge from ASBR that had been exposed to erythromycin for 47 days was used for SMA tests, the concentration of butyric acid was inhibited to a lesser extent

Conclusion: the reduction of 5 to 10% in biogas production and COD removal efficiency indicate that a substantial fraction of the microbial populations in the ASBR was resistant to the antibiotic. The conversion of butyric acid was inhibited when erythromycin was present, suggesting that fatty acid-beta oxidizing bacteria were sensitive to the antibiotic

effect of lime stabilization on the microbiological quality of sewage sludge

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] st and ards 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

Colour and organic removal from textile wastewater using water treatment wastes

Chemical treatment with coagulants has been recognized as one of the most effective methods of colour removal from textile wastewater In this study, the aluminum hydroxide present in the settled sludge from water treatment clarifiers was recovered as alum using sulfuric acid wastes from other industrial activities. The recovered alum was used in the treatment of textile wastewater in both forms of solution and suspension with mud. Its efficiency was then compared with those of commercial alum and ferric chloride. The results revealed that in textile wastewater containing disperse, acidic, ionic, cationic and direct dyes, the recovered alum suspension had a removal efficiency higher than that of the recovered alum in solution while both had higher efficiencies in removing dyes and organic matter compared to common coagulants available in the market [p<0.05]