Variations In Hydraulic Retention Time Research Articles

The effect of hydraulic retention time on stabilisation unit in anaerobic – contact stabilisation (A-CST) for treating palm oil mill effluent

The increased use of palm oil in Indonesia has triggered an increase in the quantity of Palm Oil Mill Effluent (POME). The contents of Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), as well as oils and grease in palm oil mill effluent, need to be reprocessed, in accordance with the provisions of the Ministry of Environment Regulation No. 5 of 2014, concerning Wastewater Quality Standards, before being discharged into water bodies. In this study, a modification of the treatment unit involving the integration of suspended growth and attached growth in anaerobic and aerobic processes, known as Anaerobic – Contact Stabilisation (A-CST) unit, was conducted to reduce the high concentration of organic matter in POME. This modification can shorten the detention time and reduce the land usage for treatment. The objective of this research was to analyse the performance of the modified A-CST system, based on variations in the detention time and modelling the estimation of biokinetics under unsteady-state conditions, through numerical analysis, statistical tests, and model validation. The research focused on the stabilisation unit, with variations in Hydraulic Retention Time (HRT) of 6 hours, 5 hours, and 4 hours. The results of this study revealed that, the highest percentage of removal was obtained at an HRT variation of 6 hours, with a COD 88%.

Advanced HRT-Controller Aimed at Optimising Nitrogen Recovery by Microalgae: Application in an Outdoor Flat-Panel Membrane Photobioreactor

A fuzzy knowledge-based controller of hydraulic retention time (HRT) was designed and tested in an outdoor membrane photobioreactor (MPBR) to improve nitrogen recovery from a microalgae cultivation system, maintaining the algae as photosynthetically active as possible and limiting their competition with other microorganisms. The hourly flow of the MPBR system was optimised by adjusting the influent flow rate to the outdoor environmental conditions which microalgae were exposed to at any moment and to the nitrogen uptake capacity of the culture. A semi-empirical photosynthetically active radiation (PAR) prediction model was calibrated using total cloud cover (TCC) forecast. Dissolved oxygen, standardised to 25 °C (DO25), was used as an on-line indicator of microalgae photosynthetic activity. Different indexes, based on suspended solids (SS), DO25, and predicted and real PAR, were used as input variables, while the initial HRT of each operating day (HRT0) and the variation of HRT (ΔHRT) served as output variables. The nitrogen recovery efficiency, measured as nitrogen recovery rate (NRR) per nitrogen loading rate (NLR) in pseudo-steady state conditions, was improved by 45% when the HRT-controller was set in comparison to fixed 1.25-d HRT. Consequently, the average effluent total soluble nitrogen (TSN) concentration in the MPBR was reduced by 47%, accomplishing the discharge requirements of the EU Directive 91/271/EEC.

Effect of Hydraulic Retention Time on the Levels of Biochemical Oxygen Demand and Total Suspended Solid with Simple Integrated Treatment as an Alternative to Meet the Household Needs for Clean Water

BACKGROUND: Domestic wastewater can cause health problems and pollute groundwater sources. Such pollution not only has a negative impact on health and the environment, but also on the cost in providing clean water.
 AIM: The outcome of domestic wastewater treatment through a proper technique is expected to meet the clean water quality standard for sanitation purposes.
 MATERIALS AND METHODS: The experiment was conducted to determine the effect of Hydraulic Retention Time (HRT) on the levels of Biochemical Oxygen Demand (BOD) and Total Suspended Solid (TSS) of domestic wastewater. The experiment was carried out with 6 variations of HRT, namely 1 hour, 2 hours, 4 hours, 6 hours and 8 hours with 4 repetitions. The media running process was carried out for 14 days until the reactor condition was in steady state.
 RESULTS: The results showed that the removal values ​​for COD, Oil and Fat, Ammonia and Total Coliform parameters were 68.03%, 46.51%, 69.64% and 68.99%, respectively. Based on the variation of HRT of 1 hour, 2 hours, 4 hours, 6 hours and 8 hours on the BOD parameter, the removal values ​​obtained were 11.7%, 21.3%, 34.7%, 49.0% and 64.1%, respectively. Furthermore, for the TSS parameter, the values obtained were 17.3%, 25.4%, 30.6%, 42.3% and 50.4%, respectively.
 CONCLUSION: HRT was proven to have a significant effect on the levels of BOD and TSS of domestic wastewater with a p-value of <0.05 at the 95% confidence level

Long-term performance, membrane fouling behaviors and microbial community in a hollow fiber anaerobic membrane bioreactor (HF-AnMBR) treating synthetic terephthalic acid-containing wastewater

Purified terephthalic acid (PTA) wastewater with properties of poor biodegradation and high toxicity is produced from refining and synthesis of petrochemical products. In this study, a lab-scale hollow fiber membrane bioreactor (HF-AnMBR) fed with synthetic PTA wastewater was operated over 200 days with stepwise decreased hydraulic retention time (HRT) to investigate the long-term performance, membrane fouling mechanism and microbial community evolution. Results showed that a stable chemical oxygen demand (COD) removal rate of 65.8 ± 4.1% was achieved at organic loading rate of 3.1 ± 0.3 g-COD/L-reactor/d and HRT 24 h, under which the methane production rate reached 0.33 ± 0.02 L/L-reactor/d. Further shortening HRT, however, led to the decreased COD removal efficiency and low methane bioconversion. A mild membrane fouling occurred due to the production of colloidal biopolymers and the interaction between increased colloidal substances secreted/cracked by microorganisms and membrane interface. Further 16S rRNA analysis indicated that microbial diversity and richness had changed with the variation of HRT while Methanosaeta, and Methanolinea species were always the dominant methanogens responsible for methane production. The results verify that HF-AnMBR is an alternative technology for PTA wastewater treatment along with energy harvesting, and provide a new avenue toward sustainable petrochemical wastewater management.

Modeling sulfide production in full flow concrete sewers based on the HRT variation of sewerage.

The corrosion and odor in concrete sewers are mainly related to the sulfide production, which is, under certain circumstances, directly proportional to the hydraulic retention time (HRT) of the sewer. To reduce the corrosion and control the odor in concrete sewers, it is necessary to model the production of sulfide in the concrete sewers with different HRTs. However, previous researches were mostly carried out in simulated Perspex-made sewers, and the obtained theoretical formulas based on the Monod equation were impractical because of the complexity. An actual concrete pipe with domestic sewage was employed in this study to obtain a simple but practical model, which can be applied to quantitively describe the sulfide production according to the HRT of the sewer and the chemical oxygen demand (COD) of the sewage. The empirical equation obtained was rs = (0.045 × lnHRT + 0.071) × ([COD] - b)0.6, the coefficient is a logarithmic function of the HRT, and the sulfide production rate and COD have a power relationship. Based on the data of COD and HRT obtained in the realistic sewer, the production of sulfide in the sewer can be predicted for better maintaining sewers through sulfide control.

The spatial community succession of an anaerobic baffled reactor with the variation of hydraulic retention time

Abstract A 28.4 L anaerobic baffled reactor (ABR) with four compartments was used to study the spatial community succession and the effect of hydraulic retention time (HRT) on the microorganism distribution. Furthermore, it was determined whether an ABR would promote bio-phase separation with the variation of hydraulic retention time. The high-throughput sequencing technology was used to analysethe bacteria and archaea communities in the ABR with HRT of 1.7 and 0.7 d. At the phylum level, Bacteroidetes, Euryarchaeota, Proteobacteria and Firmicutes were dominant in the bacteria community. At the family level, the distribution of bacteria and archaea communities varied in four compartments. The percentage of acetotrophic methanogens linearly increased with the compartments number. In contrast, hydrogenotrophic methanogens linearly decreased along with the compartments. The shortened HRT resulted in a decrease of acetotrophic methanogens percentage, but an increase of hydrogenotrophic methanogens in the last compartment. At HRT of 1.7 d, COD removal and methane yield of ABR were 93.4% and 16.3 L d−1, respectively. As HRT shortened to 0.7 d, COD removal and methane yield decreased to 87.7% and 12.7 L d−1, respectively. The treatment efficiency and bio-phase separation of ABR were weakened by the shortened HRT.

Performance of anammox biofilm reactor under tropical temperature

Application of anaerobic ammonium oxidation (anammox) process for mainstream wastewater in the lower temperature is a current challenge where most of the anammox reactors planted in the sub-tropical country. The purpose of this study was to analyze the performance of nitrogen removal using anammox process at room temperature in a tropical country. The experiment was carried out using 300 mL an up-flow anaerobic sludge blanket (UASB) reactor in treating low ammonia concentration artificial wastewater at tropical temperature without any adjustment. The reactor filled with 50% in volume spiral-sheet plastic (polyethylene terephthalate) as the carrier. Anammox bacteria Candidatus Brocadia sinica as seeding acclimatized in room temperature for three months before the experiment. The reactor fed with 70 mg-N/L for both ammonium and nitrite with variations in hydraulic retention time (HRT) 24 hours and 12 hours. The maximum nitrogen removal rate (NRR) achieved 0.12 kg-N/(m3·d) at nitrogen loading rate (NLR) 0.14 kg-N/(m3·d) and NRR 0.25 kg-N/(m3·d) at NLR 0.28 kg-N/(m3·d). The anammox process was stable at room temperatures (15-28°C) in a tropical country for nitrogen removal and anammox bacteria grown on plastic media.

Constructed Wetland with Rice Husk Substrate as Phytotechnology Treatment for Sustainable Batik Industry in Indonesia

This study aims to determine the vegetation efficiency of Canna indica plants and rice husk as a VFCW substrate in the batik wastewater treatment process. The VFCW pilot is made of acrylic with a length, width and height of 0.5 x 0.5 x 0.5 m respectively. Rice husk is filled as substrate to a depth of 0.3 m. Canna indica is cultivated and acclimatized then be planted in VFCW with 6 plants / units. Batik liquid waste is flowed with a hydraulic loading rate of 0.15 m3/d and variations in hydraulic retention time for 3 days, 7 days, 15 days, 21 days, and 30 days using an intermittent system. The results showed Canna indica proved to have a significant effect (p <0.05) on the removal of all parameters consisting of pH, BOD, COD, TSS, ammonia, and heavy metals Cr. Optimal efficiency for all parameters occurred at 21 days HRT which obtained TSS removal values of 91.25%, BOD5 of 91.82%, COD of 89.15%, ammonia of 96.2%, and heavy metals Cr of 81.8%. Effluents produced through the construction of VFCW with rice husks as a substrate and vegetation of Canna indica are able to meet the standards set out in East Java Governor Regulation No. 72/2013.

Anoxic Microbial Community Robustness Under Variation of Hydraulic Retention Time and Availability of Endogenous Electron Donors.

The ADNMED (Anaerobic Digestion, Nitrification, and Mixotrophic Endogenous Denitrification) system comprises a triple chamber configuration that was shown to provide high-quality effluent regarding carbon, nitrogen, and sulfide. Hydraulic retention time (HRT) was 7h in the anaerobic and anoxic chambers, and 5h in the aerobic chamber (stage A). Sewage was directly added to the anoxic chamber to provide extra organic electron donors for denitrification (stage B) to improve the nitrogen removal efficiency (stage A 47 ± 19%). The addition of sewage at a flow rate equivalent to 10% of the feed flow increased nitrogen removal efficiency to 61 ± 12%. Illumina® sequencing revealed a restructuring of the microbial community in the anoxic chamber, according to the availability of the endogenous electron donors for denitrification. At stage A, denitrification was related to the decay of biomass, while the addition of sewage during stage B stimulated the establishment of fermentative bacteria.

Psychrophilic anaerobic membrane bioreactor (AnMBR) for treating malting plant wastewater and energy recovery

This study investigated long-term operation (370 days) of a psychrophilic anaerobic membrane bioreactor for malting wastewater treatment and biogas production. At 18 ± 1 °C, despite changing the hydraulic retention time (HRT) and fluctuations of the influent COD, steady operation with an average COD removal efficiency of 92 ± 2 % was achieved. The biogas yield was 0.26 ± 0.04 L at STP/g CODremoved with an average methane content of 79.43 ± 2.69 %. The COD of supernatant and effluent decreased as the experiment proceeded. The membrane performance sustained the targeted flux for each period until day 325 of the operation. The results of membrane permeability recovery tests showed that cake layer formation was the predominant fouling mechanism. The microbial community study showed that the microbial community changed in response to variations of HRT and temperature.

NITROGEN REMOVAL IN THE ANAMMOX BIOFILM REACTOR USING PALM FIBER AS CARRIER IN TROPICAL TEMPERATURE OPERATION

Anaerobic ammonium oxidation (anammox) is the process of converting ammonium directly into nitrogen gas with nitrite as an electron acceptor under anaerobic conditions. This process is more effective than conventional nitrification-denitrification but is very dependent on several parameters, one of which is temperature. The optimum temperature range for the growth of anammox bacteria is 30-400C. The purpose of this research was to determine the efficiency of nitrogen removal by anammox process using palm fibers in the Up-Flow Anaerobic Sludge Blanket (UASB) reactor in the tropical temperature. The experiment was conducted at a laboratory scale with a variation of Hydraulic Retention Time (HRT) 24 h and 12 h using artificial wastewater. The reactor was inoculated with anammox granule genus Candidatus Brocadia. The concentration of ammonium, nitrite, and nitrate in the influent and effluent were measured using a UV-Vis spectrophotometer based on standard method. Based on the experiment, the ratio ΔNH4+-N:ΔNO2--N and ΔNO3--N:ΔNH4+-N similar with stoichiometric of anammox. The maximum Nitrogen removal performance (NRT) achieved 0.11 kg-N/m3.d at Nitrogen Loading Rate (NLR) 0.14 kg-N/m3.d and 0.20 kg-N/m3.d at NLR 0.29 kg-N/m3.d. The removal efficiency for Ammonium Conversion Efficiency (ACE) and Nitrogen Removal Efficiency (NRE) in HRT 24 h were 79% and 76%, respectively while decreased in HRT 12 h were 72% and 69%, respectively. Anammox process can be applied in the tropical temperature at a laboratory scale using a UASB reactor with palm fiber as the carrier.

Analysis of hydraulic retention time variation on the leachate treatment by using anaerobic fluidized bed reactor

Sanitary landfill activities produce leachate that contain of high pollutant wastewater of the solid waste. Anaerobic Fluidized Bed Reactor (AFBR) is one of technology that be able to treat wastewater with high pollutants. This study has purpose to analysis the effect of hydraulic retention time (12, 24, 36, and 48 hours) on the leachate treatment using AFBR. The leachate was collected from TPA Rawa Kucing that has characteristics of COD 5200-5500 mg/L and BOD 2000-2500 mg/L. Seeding and acclimatization is the first method to get the biomass of anaerobic sludge without oxygen supply. During the process, nutrient for the biomass was maintained by giving additional nutrient of glucose 33%, sanitary landfill sludge filtrate 5% and 33% of leachate and 28.3% chlorine-free water at the first formula. The second formula is by mix the glucose 20%, sanitary landfill sludge filtrate 6% and 40% of leachate and 28.3% chlorine-free water, and it took 3 months. The results are optimum variations of hydraulic retention time is 48 hours, to remove BOD, COD, and TSS at 78%, 92% and 22% efficiency. The degradation rate of the substrate (k) in anaerobic fluidized bed reactor is 0.727/day for leachate which has load of 5229 mg/L.

Kinetics on Organic Removal by Aerobic Granular Sludge in Bubbled Airlift Continuous Reactor

An assessment of aerobic granular sludge (AGS) in a bubbled airlift continuous reactor (BACR) was done to determine the AGS growth kinetics in the continuous reactor and the impact of varied hydraulic retention time (HRT) against the AGS structure. Sodium acetate was used as the sole carbon source with a 100:20 ratio of COD/N synthetic water. The system was operated at five variations of HRT, i.e. 12, 10, 8, 6, and 4 hours, with organic loading rate (OLR) ranging from 1.6 to 4.8 g COD/day in the BACR. Organic removal decreased from 73% to 52%, along with the increment of OLR, while HRT decreased from 12 hours to 4 hours. The kinetics of organic removal in the BACR were examined to get a better understanding of organic removal trends by AGS in a BACR. The models used for biomass growth analysis were the Monod, Contois, Grau second-order, and Stover-Kincannon kinetic models. This study showed that the best suited models for organic removal in BACR were the Grau second-order kinetic model with an a value of 0.1382 and a b value of 1.0776, and the Stover-Kincannon kinetic model with an Rmax of 5.8 g COD/L.day and a KB of 6.24 g COD/L.day.

Impact of hydraulic retention time and organic matter concentration on side-stream aerobic granular membrane bioreactor

This study investigated the effect of hydraulic retention time (HRT) and chemical oxygen demand (COD) concentration on membrane fouling in aerobic granular membrane bioreactor (AGMBR) in a systematic approach. Changes in HRT (7, 10, and 15 h) and COD (500, 1000 and 1500 mg/L) were applied in five operational phases, to determine the most significant parameters to control membrane fouling for enhanced AGMBR performance. Membrane permeability loss was dramatically intensified with increase in HRT from 7.5 to 15 h and COD from 500 to 1000 mg/L. The highest polysaccharide content of loosely bound EPS (0.41 mg PS/mg VSS) and soluble microbial products (SMPs) (27 mg PS/L) occurred alongside poor AGMBR performance. Variations in membrane fouling were accompanied with considerable changes in Flavobacterium, Thauera and Paracoccus populations. Analysis of variance (ANOVA) demonstrated that HRT and interaction between HRT and COD were the most significant parameters in controlling membrane fouling.

Effect of Hydraulic Retention Time on Biogas Production from Cow Dung in A Semi Continuous Anaerobic Digester

The efficiency of biogas production in semi-continuous anaerobic digester is influenced by several factors, among other is loading rate. This research aimed at determining the effect of hydraulic retention time (HRT) on the biogas yield. Experiment was conducted using lab scale self-designed anaerobic digester of 36-L capacity with substrate of a mixture of fresh cow dung and water at a ratio of 1:1. Experiment was run with substrate initial amount of 25 L and five treatment variations of HRT, namely 1.31 gVS/L/d (P1), 2.47 gVS/L/d (P2), 3.82 gVS/L/d (P3), 5.35 gVS/L/d (P4) and 6.67 gVS/L/d (P5). Digester performance including pH, temperature, and biogas yield was measured every day. After stable condition was achieved, biogas composition was analyzed using a gas chromatograph. A 10-day moving average analysis of biogas production was performed to compare biogas yield of each treatment. Results showed that digesters run quite well with average pH of 6.8-7.0 and average daily temperature 28.7-29.1. The best biogas productivity (77.32 L/kg VSremoval) was found in P1 treatment (organic loading rate of 1.31 g/L/d) with biogas yield of 7.23 L/d. With methane content of 57.23% treatment P1 also produce the highest methane yield. Biogas production showed a stable rate after the day of 44. Modified Gompertz kinetic equation is suitable to model daily biogas yield as a function of digestion time.Article History: Received March 24th 2018; Received in revised form June 2nd 2018; Accepted June 16th 2018; Available onlineHow to Cite This Article: Haryanto, A., Triyono, S., and Wicaksono, N.H. (2018) Effect of Loading Rate on Biogas Production from Cow Dung in A Semi Continuous Anaerobic Digester. Int. Journal of Renewable Energy Development, 7(2), 93-100.https://doi.org/10.14710/ijred.7.2.93-100

Development of a mathematical model for the anaerobic digestion of antibiotic-contaminated wastewater

Anaerobic digestion has been investigated as a potential method for treating antibiotic-contaminated livestock wastewaters. Antibiotic removal is mainly associated with biodegradation and sludge adsorption. In environmental concentrations, i.e., from ngL−1 to a few hundred μgL−1, cometabolism is the most likely biodegradation pathway. The overall performance of anaerobic processes may be affected by the hydraulic retention time, and these processes are strongly related to the physical characteristics of the reactor and variations in influent chemical composition. The effects of these factors can be better understood using a mathematical model. Therefore, this paper aimed to develop a model to describe an anaerobic process to treat sulfamethazine (SMZ), which was divided into two stages of microorganism growth and substrate consumption. In addition, three hypotheses regarding sulfamethazine degradation, including substrate cometabolism related to both stages and an apparent enzymatic reaction, were evaluated. A long-term kinetics structure was added to the model to simulate the process of adaptation to each new operational condition. The results showed that sudden increases in chemical oxygen demand (COD) and hydraulic retention time (HRT) had the most significant negative impact on process performance. In addition, a sudden variation of 8μg of SMZ had a similar impact on the process as did 1000mg of filtered COD. Of the degradation hypotheses, the hypothesis related to organic acid consumption was more accurate than that related to hydrolysis; however, neither could account for the response to variations in HRT. The enzymatic approach resulted in a considerably more accurate representation of the influent flow rate variations than did the cometabolic hypotheses.

PENGHILANGAN POLUTAN ORGANIK DAN PADATAN TERRSUSPENSI DI DALAM AIR LIMBAH DOMESTIK DENGAN PROSES MOVING BED BIOFILM REACTOR (MBBR)

One of the alternative technologies that could be used for domestic waste water treatment is the Moving Bed Biofilm Reactor (MBBR). MBBR in principle is activated sludge that is increased by adding media in to the reactor, so there are two treatments process happened inside, suspended growth and attached growth. This research is using bioball as a media which has surface area of ±210 m2/m3 by 20% volume of reactor volume. Wastewater treatment by MBBR uses variations of Hydraulic Retention time (HRT) 12, 8, 6, and 4 hours, then the parameters measured were BOD, COD, TSS, temperature, and pH. Result of the study shows that within HRT for 12 hours in aeration tank, removal efficiency of COD is 81,37%, BOD is 82,4%, and TSS is 90,05%. HRT for 8 hours, COD removal efficiency is 88,72%, BOD is 89,7%, and TSS is 92,06%. HRT for 6 hours, COD removal efficiency is 85,48%, BOD is 80,15%, and TSS is 94,85%. HRT for 4 hours, COD removal efficiency is 81,07%, BOD is 87,88%, and TSS is 94,86%. With a retention time of 4 hours, the effluent results domestic wastewater treatment using MBBR has met quality standards in accordance with KEPMEN LH no. 112 of 2003 on Domestic Wastewater Quality Standard and Jakarta Governor Regulation no. 122 of 2005 on Domestic Wastewater Management in Special Province of Jakarta. Keywords: Domestic wastewater, MBBR, bioball.

Dynamics of Archaeal and Bacterial Communities in Response to Variations of Hydraulic Retention Time in an Integrated Anaerobic Fluidized-Bed Membrane Bioreactor Treating Benzothiazole Wastewater.

An integrated anaerobic fluidized-bed membrane bioreactor (IAFMBR) was investigated to treat synthetic high-strength benzothiazole wastewater (50 mg/L) at a hydraulic retention time (HRT) of 24, 18, and 12 h. The chemical oxygen demand (COD) removal efficiency (from 93.6% to 90.9%), the methane percentage (from 70.9% to 69.27%), and the methane yield (from 0.309 m3 CH4/kg·CODremoved to 0.316 m3 CH4/kg·CODremoved) were not affected by decreasing HRTs. However, it had an adverse effect on membrane fouling (decreasing service period from 5.3 d to 3.2 d) and benzothiazole removal efficiency (reducing it from 97.5% to 82.3%). Three sludge samples that were collected on day 185, day 240, and day 297 were analyzed using an Illumina® MiSeq platform. It is striking that the dominant genus of archaea was always Methanosaeta despite of HRTs. The proportions of Methanosaeta were 80.6% (HRT 24), 91.9% (HRT 18), and 91.2% (HRT 12). The dominant bacterial genera were Clostridium in proportions of 23.9% (HRT 24), 16.4% (HRT 18), and 15.3% (HRT 12), respectively.

Model of Suspended Solids Removal in the Primary Sedimentation Tanks for the Treatment of Urban Wastewater

Primary settling tanks are used to remove solids at wastewater treatment plants and are considered a fundamental part in their joint operation with the biological and sludge treatment processes. The aim of this study was to obtain a greater understanding of the influence of operational parameters, such as surface overflow rate, hydraulic retention time, and temperature, on the removal efficiency of suspended solids and organic matter by the measurement of chemical oxygen demand and biochemical oxygen demand in the primary sedimentation process. The research was carried out in a semi-technical primary settling tank which was fed with real wastewater from a wastewater treatment plant. The physical process was strictly controlled and without the intervention of chemical additives. Three cycles of operation were tested in relation to the surface overflow rate, in order to check their influence on the different final concentrations. The results obtained show that the elimination efficiency can be increased by 11% for SS and 9% for chemical oxygen demand and biochemical oxygen demand, for variations in the surface overflow rate of around ±0.6 m3/m2·h and variations in hydraulic retention time of around ±2 h. The results also show that current design criteria are quite conservative. An empirical mathematical model was developed in this paper relating SS removal efficiency to q, influent SS concentration, and sewage temperature.

Performance of modified anaerobic inclining-baffled reactor treating recycled paper mill effluent: effects of influent chemical oxygen demand concentration and hydraulic retention time

ABSTRACTThe performance of modified anaerobic inclining-baffled reactor (MAI-BR) treating recycled paper mill effluent (RPME) was investigated by varying the influent chemical oxygen demand (CODin) concentration from 1000 to 4000 mg/L, and the hydraulic retention time (HRT) from 3 to 1 day, corresponding to an organic loading rate increase from 0.33 to 4 g COD/L day. Throughout 126 days of operation, a maximum removal efficiency of up to 96% of chemical oxygen demand (COD) and 99% of biological oxygen demand, methane (CH4) yield of 0.259 L CH4/g COD, and a stable effluent pH of 6.5 were achieved. Furthermore, the compartmental performance showed that most of the organic substrates were removed in the initial two compartments, resulting in low pH and alkalinity levels and a high concentration of volatile fatty acids. Overall, the results showed that the MAI-BR successfully treated RPME, and the performance was affected by the variation of HRT more than the CODin.