Showing 19 results for Aerobic
M Ahmadi, H Ganjidoust, B Ayati,
Volume 1, Issue 2 (3-2009)
Abstract
Background and Objectives: Upflow Sludge Blanket Filtration (USBF) system is a modification of the conventional activated sludge process that incorporates an anoxic zone with an upflow sludge blanket filtration clarifier in one bioreactor. It has no inherent capacity limits and is used in a wide range of applications in municipal, industrial and agricultural wastewater treatment. The main objective of this study was to evaluate the performance of a continuous USBF reactor for the treatment of sugar industrial wastewater.
Materials and Methods: Sixty liter laboratory pilot scale plant was made of plexiglass consists of 14 liter anoxic zone, 38 liter aerobic zone and 8 liter clarifier. Used molasses for raw wastewater was obtained from Varamin Sugar Company. During the study, the wastewater has been initially fed to anoxic zone of the bioreactor. It mixed with recycled activated sludge returned from the clarifier and the mixed liquor entered into aerobic zone of the bioreactor. From aeration zone, the mixed liquor passed through the sludge zone at the bottom of the clarifier which was then separated by upflow sludge blanket filtration and then the clear water discharged from the system. To complete the internal circulation loop, collected activated sludge at the bottom of the clarifier was recycled to the anoxic zone.
Results: Experimental studies indicated that average removal efficiency of COD with HRTs from 21 to 26 hours in the aerobic zone and from 8 to 10 hours in the anoxic zone were from 77 to 97 percent depended on input feed (1000 to 30000 mg/L).
Conclusion: USBF as an advanced biological process had a proper COD removal efficiency for the biological treatment of sugar industries wastewater compared to other researchers methods.
G Moussavi, A Jamal, H Asilian,
Volume 1, Issue 2 (3-2009)
Abstract
Background and Objectives: A conventional treatment to stabilize the excess activated sludge is the aerobic digestion process but due to long aeration time, it requires large equipments as well as high investment cost. Because of high oxidation potential of ozone, sludge ozonation enhances stabilization rate and reduces sludge treatment equipment size and cost. Therefore, in this study, the combination of pretreatment with ozone and aerobic digestion processes were investigated.
Materials and Methods: The experimental set-up consisted of an ozone generator and ozonation reactor with the total volume of 2 L. Removal percentages of TSS, VS, total and soluble COD, HPC, fecal coliform and settable solids were measured in integrated process compared to the single ones.
Results: The results of this research indicated that the aerobic digestion of waste activated sludge during 10 days could reduce 38% of volatile solids and thus obtaining the EPA standard. Also, the results of combined ozonation and aerobic digestion revealed that the pre-ozonation at 0.25 g O3/g TS or 0.5 g O3/g TS with 6 or 3 days aeration, respectively, could achieve 38% reduction in VS and hence the requirement set by EPA. Therefore, integration of pre-ozonation with aerobic digestion can significantly reduce the digestion time to attain the standards.
Conclusion: The sludge pre-ozonation with low dose of ozone due to solids disintegration can enhance the efficiency of aerobic digestion in waste activated sludge stabilization, and consequently decrease size of equipments, air requirement, investment and probably operation cost.
M.j Zoqi, A Ghavidel,
Volume 2, Issue 2 (9-2009)
Abstract
Backgrounds and Objectives:A number of different technologies have recently been studied todetermine the best use of biogas, however, to choose optimize technologies of using biogas for energy recovery it is necessary to monitor and predict the methane percentage of biogas. In this study, a method is proposed for predicting the methane fraction in landfill gas originating from Labscalelandfill bioreactors, based on neural network.
Materials and Methods: In this study, two different systems were applied, to predict the methane fraction in landfill gas as a final product of anaerobic digestion, we used the leachate specifications as input parameters. In system I (C1), the leachate generated from a fresh-waste reactor was drained to recirculation tank, and recycled. In System II (C2), the leachate generated from a fresh waste landfill reactor was fed through a well-decomposed refuse landfill reactor, and at the same time, the leachate generated from a well-decomposed refuse landfill reactor recycled to a fresh waste landfill reactor.
Results: There is very good agreement in the trends between forecasted and measured data. R valuesare 0.999 and 0.997, and the obtained Root mean square error values are 1.098 and 2.387 for training and test data, respectively
Conclusion: The proposed method can significantly predict the methane fraction in landfill gasoriginating and, consequently, neural network can be use to optimize the dimensions of a plant using biogas for energy (i.e. heat and/or electricity) recovery and monitoring system.
M Eshraghi, B Ayati, H Ganjidoust,
Volume 2, Issue 4 (3-2010)
Abstract
Backgrounds and Objectives : Nitrogen compounds in wastewater are mainly in four types of organic, am- monia, nitrite and nitrate. Total nitrogen concentration in municipal wastewater is usually within 25 to 45 mg/L as nitrogen. The most important problem with nitrogen is its oxygen demand and human health effect.
Materials and Methods: Anaerobic Baffled Reactor (ABR) is a system in which baffles are used to direct wastewater flow. During 9 months study, a 15 liter modified ABR (104*30*15 cm) with eight baffled com- partments was used for nitrification-denitrification processes. In the seventh compartment, the wastewater was aerated to oxidize ammonia to nitrite and nitrate.
Results : Denitrification was done in the first four compartments with removal efficiency from 60 to 84 per- cent for nitrite and nitrate, respectively. During the shock loading study (4 times of the last influent), a sharp decrease in nitrogen removal rate was observed which was then returned to the previous efficiency after 11 days. Artificial neural network was used to evaluate and process the data in which the observed error in 10 patterns was less than 15 percent.
Conclusion : Anaerobic baffled reactor with an influent of up to 200 mg/L has capability to remove total nitrogen concentration to less than the standard level of Iranian Department of Environment of 50 mg/L as nitrate and 10 mg/L as nitrogen.
M Malakootian, N Jafarzadeh Haghighi Fard, M Ahmadian, M Loloei,
Volume 3, Issue 2 (7-2010)
Abstract
Backgrounds and Objectives: Untreated leachate is discharging into the environment in the many countries of worldwide. Leachate treatment methods have not been unified so far due to variable composition of leachate. Moreover, the uncontrolled management of leachate, cause many environmental dissociates. The aims of this study apply the Fenton process to decrease the pollutants of Kerman leachate.
Materials and Methods: Rawleachatewas obtained fromcompactor vehicles used for the collection of Kerman city solid waste, before final disposal. In order to removal of biodegradable organic compounds, a rector was built based on characteristics of landfill Kerman city and raw leachate underwent anaerobic treatment in this pilot. In the next stage, treated leachate in the pilot, was affected by Fenton process. The optimized parameters in Fenton process including pH, reaction time and dosage of H2O2 and Fe2+ were also studied.
Results: The results showed that TSS, BOD5 and COD decrease to 62*, 96*and 89*, respectively, after 60 days treatment in the pilot. BOD5/COD ratio also decreased from 0.6 to 0.2 in anaerobic treated leachate. In optimum condition (pH=3, reaction time=75 min, Fe2+=1400 mg/L and H2O2 = 2500 mg/L) maximum COD removal was 78 * by Fenton process. BOD5/COD ratio increased from 0.2 to 0.51 which showed an increase in biodegradability of leachate as a result of Fenton process.
Conclusion: anaerobic biologically treatment followed by Fenton processes could be assumed as an efficient process that could improved the leachate quality. Biological treatment to reduce leachate pollution alone was not enough. The most important Fenton process advantage is reduction of refractory and toxic leachate compounds and increasing leachate.s biodegradability.
Mahdi Kargar, Amir Hossein Mahvi,
Volume 5, Issue 1 (4-2012)
Abstract
A
MicrosoftInternetExplorer4
Backgrounds and Objectives: Large quantities of sludge are produced in
biological wastewater treatment. Because this sludge is highly rotten, it
should be stabilized before its disposal. Aerobic and anaerobic digestion is
widely considered as stabilization techniques. Because of high retention time
and sludge dewatering difficulties, reduction in retention time, operation and
maintenance should be given into consideration. Ultrasonic process increases
the enzymatic activity, so decreases the hydrolysis time, a limiting factor in
digestion process, and contributes to the decrease of the detention time. The
objective of this investigation is to determine the effect of ultrasound in
improving dewatering and stabilization of aerobic and anaerobic digested
sludge. In addition, the impact of ultrasonic treatment on improvement of
sludge dewatering and aerobic and anaerobic digestion is compared.
Materials and Methods: In this survey, samples of aerobic and
anaerobic digestion were collected from local full-scale Garb Town
and Tehran South wastewater treatment plant, respectively. The grab samples
were collected for 4 month from July to October 2010. Total numbers of 20
samples were collected biweekly for each type of digestion. Each sample was
sonicated for 15, 30, 60, and 90 min under 35 and 131 kHz frequencies
separately. Total solids, volatile solids , pH, temperature , total COD,
dissolved COD and settle able solids were measured. Ultrasound bath of the
solution in a 300 mL glass reactor was performed as a bath reactor with power
of 500 W.
Result: The results showed that the application of ultrasonic
wave increased dissolved COD and temperature and decreased volatile solid, pH
and settle able solids. Application of ultrasonic wave with frequency of 131
kHz decreased the VS and increased the dewatering of sludge more effective than
the 35 kHz frequency and the highest performance was at 15 min of time and 131
kHz of frequency. Also sonication method showed better efficiency for anaerobic
sludge samples compared to the aerobic sludge samples.
Conclusion: The results obtained showed that digestion
and dewatering properties of sludge improved by ultrasonic application.
Therefore it can be used as an alternative method for the sludge treatment.
!mso]>
ject classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui>
Ali Almasi, Meghdad Pirsaheb, Abdollah Dargahi,
Volume 5, Issue 1 (4-2012)
Abstract
MicrosoftInternetExplorer4
Background and Objectives: Phenol is one of the
aromatic compounds, which due to its high toxicity and its presence in the
industrial effluents, should be removed and prevented it, to the receiving water resources.
The natural biological plant has been accepted as one of the most feasible,
eco-friendly and cost-effective options for the treatment of pollutants such as
Phenol.
The aim of this study is efficiency evaluation of the anaerobic stabilization
pond performance in removing phenol and other organic compounds from Kermanshah oil refinery wastewater.
Materials and Methods: The method of study
was experimental and analytical, a laboratory scale anaerobic stabilization pond,
with dimensions of 1 × 1 × 0/2 m, using fiberglass sheet with a thickness of 6
mm was designed and built up. In this study The hydraulic retention time and
hydraulic loading rate were expected 2 days and 95 liters per day respectively.
Organic loading rate for anaerobic pond was 100 g/m
3. After
starting, seeding and biological stability, samples were taken. Initial phenol
concentration was added about of 100 mg/l to pilot input, then the parameters
such as NH
3, PO
4 and Phenol were measured by Varian
spectrophotometer model UV-120-02 in the wavelength 425, 690, 500 nm
respectively. TCOD, SCOD, TBOD, SBOD, pH
and ORP were measured according to the standard methods of water and
wastewater.
Results: The results showed that the removal efficiency of NH
3,
PO
4, phenol, TCOD, SCOD, TBOD, SBOD in the anaerobic pond were
obtained 91.51%, 64.34%, 89.82% 74.99 % 73.34% 71.75%, 68.9% respectively.
Conclusion: The results showed that the ability for phenol and other organic compounds
removal in anaerobic pond using petroleum refinery wastewater is higher than
the other systems which are expensive and complex.
!mso]>
ject classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui>
Ensieh Taheri, Mahdi Hajian Nejad, Mohammad Mahdi Amin, Hossein Farrokhzadeh, Maryam Hatamzadeh, Marzieh Vahid Dastjerdi,
Volume 5, Issue 1 (4-2012)
Abstract
AR-SA
MicrosoftInternetExplorer4
Background and Objectives: Aerobic sludge granulation is an
advanced phenomenonin which its mechanisms have not been understood.
Granulation can be a promising and novel biological wastewater treatment
technology to eliminate organic and inorganic materials in future. High
salinity is a parameter which leads to plasmolisatian and reduction of the cell
activity. This could be a problem for biological treatment of the saline
wastewater. Aerobic granule was formed and investigated during this study.
Materials and Methods:
This study is an intervention study on the treatment of wastewater with
500-10000 mg/L concentration of NaCl by sequencing batch reactor. Asynthesized
wastewater including nutrient required for microorganism's growth was prepared.
Input and output pH and EC were measured. Range of pH and DO varied between
7-8, and 2-5 mg/L, respectively. SEM technology was used to identify graduals
properties.
Results: In terms of color, granules divided
into two groups of light brown and black. Granule ranged in 3-7mm with the
sediment velocity of 0.9-1.35 m/s and density of 32-60 g/L.Properties of
granules were varied. Filamentous bacteria and fungi were dominant in some
granules. However non filamentous bacteria were dominant in others. EDX
analysis indicated the presence of Ca and PO
4.
Conclusion: Granules
with non filamentous bacterial were compact and settled faster. Presence of
different concentrations of salinity leaded to plasmolysis of the bacterial
cells and increased concentrations of EPS
in the system as a result of
which granulation accelerated
.
Zhila Moradi-Khatoonabadi, Yahya Maghsoudlou, Hamid Ezzatpanah, Morteza Khomeiri, Mehdi Aminafshar,
Volume 6, Issue 4 (3-2014)
Abstract
Background and Objective: Milk and milk products are very suitable medium for growing microorganisms (e.g. Bacillus cereus). B. cereus is spore former bacilli, which easily survives during pasteurization and makes several problems in dairy industries. The aim of this study was to investigate aerobic spore and B. cereus of receiving raw milk from three UF plants. Materials and Methods: Samples were gathered from raw milk transport tankers arrived to plants during 30 days in winter. Also, the swab test was used for detection of B.cereus residual on milk contact surfaces. Results: High contamination level of aerobic spores (AeSC) and especially B.cereus were found in most samples compared with the criteria established by national and international standards. Although total viable count (TVC) in samples from industrial farms (IF) was lower than those from traditional farms (TFs) and milk collection centers (MCCs), considerable AeSC and B.cereus were transmitted to the UF plants from IFs. The highest and lowest TVC and B.cereus were found in samples from IFs and MCCs, respectively. In addition, our investigation in IFs revealed that teats contamination to soil and feces, as well as contaminated bedding might were the most important sources of B. cereus and AeSC of raw milk. Moreover, the results of swab tests confirmed that the “cleaning in place” system may not remove B.cereus effectively. Conclusion: It seems that for classifying raw milk quality, AeSC might be used as a more effective quality factor than TVC. Management commitment is effective to improve quality by balance between the amount and quality of receiving raw milk. This leads to the lower contamination in dairy plants and final products.
N Navidjouy, M Jalali, H Khorsandi, Hossein Movahedian,
Volume 7, Issue 1 (7-2014)
Abstract
Background & Objectives: Listeria bacterium resists to the sludge digestion conditions and Listeria monocytogenes is the most important of them. Sludge produced in the north Isfahan wastewater treatment plant is stabilized by anaerobic digesters and is used for fertilizing agricultural lands after drying in the sludge drying beds. Based on the importance of the subject, the objective of this study was evaluation of sludge processing units efficiency, particularly anaerobic sludge digestion for reduction or removal of Listeria. Materials and Methods: In this descriptive study, samples were collected weekly from sludge processing units 13 times in north Isfahan wastewater treatment plant according to standard methods over three months. Listeria bacteria were enumerated and isolated by triple-tube fermentation method and U.S Department of Agriculture method respectively. Isolated Listeria were confirmed by phenotypic method and then bacterial species were diagnosed differentially by biochemical carbohydrate fermentation and CAMP test. Results: Contamination of raw, stabilized and dried sludge at least to one of L. Monocytogenes, L. Innocua and L. Seeligeri species was 100, 92.3 and 53.8 percent respectively. Anaerobic sludge digesters efficiency to remove L. Monocytogenes, L. Innocua and L. Seeligeri species was determined 64.7, 39.72, and 100 percent while the efficiency of drying sludge beds for L. monocytogenes and L.innocua species removal was 73.4 and 96.68 percent respectively. Conclusion: Listeria monocytogenes is more resistant than other identified species against the sludge processing conditions. Thus, the use of sludge as fertilizer can cause the spread of this bacterium in the environment and agricultural products pollution.
S. A. Mirzaee, M.m Amin, M Sarafraz, M Heidari, M.m Ahmad Moazzam,
Volume 7, Issue 4 (1-2015)
Abstract
Background & Objectives: Disposal of pharmaceutical compounds to environment as an emerging pollutants cause concerns significantly and it is necessary to use new methods of sewage treatment for removal of these compounds. The aim of this study was to investigate the inhibition effects of metronidazole before and after using UV254/H2O2 process on specific methanogenic activity of.anaerobic biomass. Materials & Methods: Fourteen anaerobic digestion tests were carried out at batch scale before and after using UV254/H2O2 process in 500 ml reactors with 30% anaerobic biomass and 70% substrate. The liquid displacement method was used. Duration of each test was in the range of 10-17 days. Results: Cumulative Biomethane production in concentrations of 1, 5, 10, 25, 50, and 100 mg/l metronidazole was 34.04, 95.12, 100.86, 3.28, 27.88, and 6.97 ml respectively. This production was 800.73, 243.54, and 10.66 ml in concentrations of 25, 50, and 80 mg/l respectively using UV254/H2O2 process as pretreatment at 60 min retention time. Biomethane production in concentrations of 80,120, and 150 mg/l was 377.2, 380.48, and 63.14 ml respectively at 90 min retention time. Conclusion: Different concentrations of metronidazole had an inhibition effect on anaerobic digestions and therefore the efficient pretreatment method is needed to reduce this inhibition effect. The UV254/H2O2 process is an effective method for degradation and conversion of metronidazole to more biodegradable compounds for anaerobic bacteria consumption and, in turn, to increase biogasproduction in anaerobic digestions.
Sar Mousavi, M Parvaneh,
Volume 9, Issue 2 (9-2016)
Abstract
Background and Objectives: Conventional methods of leachate treatment are inefficient due to high pollution loads and characteristics of the leachate. In recent years, an integrated method has been developed considerably. The aim of this research was to evaluate the effect of powdered activated carbon on the treatment of landfill leachate of Kermanshah City by a columnar aerobic sequencing batch reactor.
Materials and Methods: This study was carried out in three reactors having a total volume of 2000 mL and each having an effective volume of 600 mL in the bench scale. To the reactors 2 and 3 that were similar from environmental conditions and operation point of view with reactor 1 (with no carbon powder), 5 and 10 g/L of PAC were added, respectively. The effects of different doses of PAC (0, 5, 10 g/L) and hydraulic detention times (HRT = 48, 96, 144 h) were investigated in order to remove the Chemical Oxygen Demand (COD) and ammonia nitrogen (NH3-N) from the leachate. The efficiency was investigated using two -way ANOVA test in SPSS software (Ver. 16).
Results: The results of two-way ANOVA showed that there was a significant difference (P-value=0.001) between the removal efficiency of COD and NH3–N at different HRTs with different doses of PAC. The highest removal efficiency achieved at HRT=144 h for COD and NH3-N was in Reactor 1 were 50.11 ± 4.42 and 19.85 ± 1.49%; in reactor 2: 55.67 ± 1.6 and 25.7 ± 0.89%; and in reactor 3: 58.02 ± 3.99and 25.48 ± 1.7%, respectively.
Conclusion: It can be concluded that the combination of biological - activated carbon compared with the biological process, can remove COD and NH3–N of strong sewages such as landfill leachate, although achieving standard treatments using this method is not possible.
M Aqanaghad, G Moussavi,
Volume 9, Issue 3 (12-2016)
Abstract
Background and Objective: Being low cost of building and operation, anaerobic baffled reactor is considered superior to aerobic methods of wastewater treatment, especially for small communities. However, it needs to be studded for upgrade and overcome of its limitations. The purpose of this study was to evaluate the performance of FABR and RABR reactors for the municipal wastewater treatment at laboratory scale and in field conditions to determine their optimum conditions in reaching effluent discharge standards.
Materials and Methods: This study was conducted in Khoy wastewater treatment plant. FABR was operated for 267 days with hydraulic retention time of 18-48 h and RABR was operated for 90 days with media bad rotation of 10-50 rpm. The reactors were fed in line from the wastewater canal. Using composite sampling, 224 samples were taken from the inflow and outflow of the reactors and each sample was analyzed for parameters of COD, BOD, TSS, VSS, TKN, and TP.
Results: The reactor startup took about 107 days. FABR removal efficiency was 93-80, 21-10, and 30-21% for COD, TKN, and PO4 respectively at HRT of 48-18 h. FABR reached effluent disposal standard of TSS, COD, and BOD in all conditions and optimum HRT of 36 h. RABR reached to these standards at HRT 24 h and 50 rpm. However, none of them could meet the nutrient effluent standards.
Conclusion: FABR is an appropriate system for municipal wastewater treatment but for reaching N and P effluent standard, it should be combined with aerobic post-treatment. Moreover, in order to reuse the reactor's nutrient-rich effluent for irrigation; it can be reused as subsurface irrigation.
R Rafiee, M Moeinaddini, N Khorasani,
Volume 11, Issue 1 (6-2018)
Abstract
Background and Objective: The aim of this study was to assess the sensitivity and uncertainty analysis of a mass balance model to estimate the rate of aerobic processes in a landfill.
Materials and Methods: Monte Carlo simulation is a common method to evaluate uncertainty of the results of a model. Here, we used a Monte Carlo (MC) simulation. The data obtained from the experiments were used as a baseline. Considering a uniform Probability Distribution Function (PDF) within ±15% deviation, samples were taken from the baseline data. Using randomly selected inputs, model was executed for 1000 iterations and outputs were evaluated. Then, the total Sobol index for each input parameter was determined. The uncertainty of each output was presented by standard error and means observed in MC simulation.
Results: The results of this study revealed that while the uncertainty for the rate of composting process was mainly originated from the measured value of CO2 flux, the evaluated value for the rate of anaerobic digestion process was highly influenced by the value measured for CH4 emission flux. All inputs contributed equally to the uncertainty in the evaluated values for the rate of methane oxidation process. Although a variability of 15% was assumed for the model inputs, the mean value for the outputs from Monto Carlo simulations were close to those obtained by using base values that were in most cases within ±10% limit.
Conclusion: The majority of the uncertainty in the outputs came from the variability in the measurement of the flux of CH4 and CO2. The error in these parameters, however, can be minimized by increasing frequency and replicates of gas samples as these parameters are measured directly for each location.
A Jonidi Jafari, M Farzadkia, M Gholami, M Mohagheghi,
Volume 11, Issue 2 (9-2018)
Abstract
Background and Objective: Nowadays, the increasing use of antibiotics to control diseases and mismanagement and inappropriate disposal of medicinal wastes cause environmental problems and threatens human health. The present study was conducted to determine removal of antibiotic Metronidazole as one of the most used drugs during the process of composting.
Materials and Methods: In this experimental study, a mixture of livestock manure, fruit, straw and sludge were used for the preparation of compost. Duration of the process was 40 days. Metronidazole was added to the compost reactors at three concentrations of 20, 50 and 100 mg/kg. Totally, 42 Samples were taken weekly. HPLC was used to analyze the samples. The experiment was repeated twice. SPSS22 software was used to analyze the results.
Results: The rate of Metronidazole removal after day 21 and end of the thermophilic phase was 99.9, 96.73 and 93.48 % in the reactors contained 20, 50 and 100 mg/kg, respectively. Increasing concentrations in the reactors caused the removal rate to decrease, while increasing removal time caused to increase the removal rate. At the end of the process, the removal rate for all three reactors was 99.99 %. The physico-chemical properties of the final compost were within the national standard.
Conclusion: The use of an aerobic composting process to degrade antibiotic Metronidazole is an economical, effective and, environmentally friendly method. At the end of the process, 99.99 % of Metronidazole was degraded.
Abdolmotaleb Seid Mohammadi, Ghorban Asgari, Reza Shokoohi, Parastoo Shahbazi,
Volume 13, Issue 3 (11-2020)
Abstract
Background and Objective: Considering the importance of alkalinity in pH regulation and its buffering role, in this study, the effect of inlet wastewater alkalinity on the efficiency of the anaerobic unit of the wastewater treatment plant. Moreover, a superior chemical compound in providing alkalinity to wastewater was investigated.
Materials and Methods: This study was performed in the treatment plant to determine the relationship between input alkalinity and removal efficiencies of COD, BOD5 and TSS. In order to determine the optimal alkali material for superb anaerobic wastewater performance, four common chemical substances including, NaOH, Na2CO3, Ca(OH)2 and MgO were selected and examined using One Factor At Time (OFAT) test method.
Results: According to the results maximum removal efficiencies were obtained 62, 66.6 and 71.2% for COD, BOD5 and TSS, respectively under alkaline condition of 1260 mg/L CaCO3. Furthemore, the optimal dose to supply one unit of alkalinity by Na2CO3, Ca(OH)2 and MgO were 0.53, 0.54 and 0.3 mg/L, respectively. These values were obtained 5 min contact time and mixing rate of 150 rpm. However, for NaOH the optimal dose supply was obtained 0.35 mg/L for 3 min contact time and mixing rate of 100 rpm.
Conclusion: In conclusion, the performance of anaerobic baffled reactor is highly related to the supply of influent alkalinity to the reactor. In addition, the use of MgO can be considered as a suitable alkaline substance to neutralize acidic wastewater and provide alkalinity for ABR system.
Reza Barati Rashvanlou, Mahdi Farzadkia, Abbas Ali Moserzadeh,
Volume 14, Issue 1 (5-2021)
Abstract
Background and Objective: Hydrolysis of fat, oil and grease by ultrasonic waves is a pre-treatment method before anaerobic digestion which can change their physical, chemical and biological properties. The main purpose of this study was to investigate the efficiency of ultrasonic waves to improve the hydrolysis process and its use as an auxiliary substrate to increase the efficiency of anaerobic digestion process along with municipal sewage sludge.
Materials and Methods: Sampling of fat and oil of the degreasing unit and physical preparation by conducting ultrasonic waves with frequencies of 20 kHz and current density of 0.012-0.14 W/mL within 0-12 min were performed. The efficiency of pretreatment process were performed through tests such as soluble chemical oxygen demand (SCOD), and lipase enzyme activity. In addition, the anaerobic digestion process were evaluated by measuring the TS, VS, VA (volatile acidity), alkalinity, biogas production and biogas methane content.
Results: The results showed that the highest increase in the activity of lipase enzyme under ultrasonic effect with a power of 0.1 w/mL was obtained after 8 minutes. Organic loading with 10%, 20% and 40% FOG/MSS ratios: resulted in 55%, 66% and 64% increase in methane production compared to the control samples, respectively. Organic loading over the 40% FOG/MSS caused a limitation in the simultaneous digestion process.
Conclusion: The results show that ultrasonic wave pretreatment with optimal power and time can improve the hydrolysis of TFOG while increasing the activity of lipase enzyme and also its use as an auxiliary substrate can enhance digestion performance and make digestion more stable.
Abbas Ali Moserzadeh, Gholamreza Nabi Bidhendi, Nasser Mehrdadi, Mohammad Javad Amiri,
Volume 17, Issue 1 (6-2024)
Abstract
Background and Objective: A high concentration of Hydrogen Sulfide in biogas is a major problem associated with anaerobic digestion of waste rich in sulfate. It disrupts the functional process and reduces the lifespan of biogas facilities. The micro-aerobic (MA) process is an alternative method for direct sulfurization.
Materials and Methods: The effect of sulfate loading (200, 500 and 700 mg/L) on H2S in biogas were investigated. Subsequently, the effect of MA process (0.88, 1.04, 1.34 NL/day) on H2S reduction in biogas production was evaluated. Additionally, oxidation-reduction potential (ORP) and pH were measured. Finally, under optimal conditions, the biogas volume and the content of CH4 and CO2 in biogas were determined.
Results: The results indicated that there were no significant differences in biogas volume production between the reactor fed with 200 mg/L sulfate and the control. However, the biogas production in reactors with 500 and 700 mg/L sulfate decreased to 4103 and 3929 mL, respectively. The H2S levels in control and reactors with 200, 500, 700 mg/L sulfate were 0.35, 0.46, 2.4, and 1.8%, respectively. In reactors with MA at rates of 0, 0.88, 1.04, 1.34 NL/day, the H2S levels were 1.95%, 0.9%, 0.4% and 0.1% (V/V) in biogas, respectively. The pH in reactor varied between 2.7 and 4.7, and the ORP was measured between -281 and -291 mV. Statistical analysis shows that no significant difference was observed between the average daily production of biogas with MA process of 0.88 and 1.04 NL/day. However, MA with 1.34 NL/day resulted in a decrease in biogas production.
Conclusion: The results indicated MA at a rate of 1.04 NL/day is a favorable option for the treatment of sulfate-rich urban wastewater sludge due to its efficiency in H2S removal.
Fariba Asghari, Ayoob Rastegar, Mohammad Hossien Saghi,
Volume 17, Issue 4 (3-2025)
Abstract
Background and Objective: Composting is a sustainable solution for recycling organic solid waste (OSW). Various compounds can be used to enhance the quality of compost. This study aimed to investigate the effects of zeolite on the physical and chemical characteristics of compost produced through the anaerobic process.
Materials and Methods: This analytical study was conducted in 1402 at Kimia Sabzevar Company, located 5 km from Rudab Road. Cow manure and natural clinoptilolite zeolite were used in varying proportions (0%, 5%, 10%, 15%, and 20% of the total reactor volume) to prepare fertilizer via the anaerobic method. After 30, 45, and 60 days, a total of 90 samples were collected and sent to the laboratory for analysis. Parameters such as pH, electrical conductivity, temperature, carbon-to-nitrogen ratio, and nitrate content were measured to evaluate the quality of the fertilizer product.
Results: The results showed that in the early stages, pH changes were less pronounced in treatments with varying zeolite percentages, ranging from 7.9 to 8.57. The addition of zeolite in the composting process influenced temperature dynamics, with higher zeolite percentages maintaining elevated temperatures. Moreover, the nitrate content increased by 15% during the process.
Conclusion: The findings indicate that adding zeolite to fertilizer enhances temperature stability, accelerates the composting process, and reduces the time required for fertilization. Additionally, zeolite improved the physicochemical properties of the fertilizer produced through the anaerobic process.
