Modified Stover-Kincannon Model Research Articles

Anaerobic biodegradation of real pharmaceutical-grade lactose manufacturing wastewater in a modified Internal Circulation Reactor

Pharmaceutical-grade lactose (PL) manufacturing generates wastewater containing high concentrations of biodegradable organic matter. In the absence of a suitable alternative, industries handle such concentrated streams by completely evaporating the entire stream and disposing of water-soluble solid residue in a landfill. Such a process is energy-intensive, and nothing useful is recovered from the stream. This study demonstrates the efficient and sustainable anaerobic biodegradation of real PL wastewater using a lab-scale internal circulation reactor (ICR) combined with an external recirculation system. The effects of feed Chemical Oxygen Demand (COD) concentration, organic loading rate (OLR), and hydraulic retention time (HRT) on COD removal efficiency, methane production, and the volatile fatty acids/alkalinity (VFA/ALK) ratio were evaluated. Under the highest feed COD concentration of 60,000mg/L, OLR of 4.5kg/m³∙d, and HRT of 13.33 days, the system achieved an average COD removal efficiency of 93.8% with methane production of 25.2L/d (specific methane generation of 0.32L/g CODremoved). By increasing the up-flow velocity from 0.044m/h (without external recirculation) to 1.5m/h (with external recirculation), COD removal improved from 63.6% to 93.4%, and methane production increased from 7.5L/d to 14L/d. The kinetics of COD removal fitted well in the modified Stover-Kincannon model (R2 = 0.99). A unique finding of this study is that the loose anaerobic sludge became granulated after 120 days, with 50% of the granules having diameters ≥ 2.0mm. The results of this study establish anaerobic biodegradation as a suitable treatment option for PL wastewater, thereby achieving UNSDG 6 (Clean Water and Sanitation) and 7 (Affordable and Clean Energy).

Ideal performance assessment of non-recirculating anaerobic fluidized bed reactors treating low to high strength organic loads with low retention time

This study investigated the ideal performance of non-recirculating Anaerobic Fluidized Bed Reactors (AnFBRs) for treating organic wastewater of varying strengths under low Hydraulic Retention Time (HRT). Four 4.58 L AnFBRs were used to treat synthetic wastewater with an Organic Loading Rate (OLR) ranging from 4.50 to 40.11 gCOD/L-d, and HRT between 1.1 and 4.4 hours. The AnFBRs achieved high removal efficiencies ranging from 83 % to 96 % at steady state, except during the organic shock load, which reduced removal performance to 12 %. Shortened HRT conditions led to a decreasing trend in reactor pH due to an incomplete anaerobic cycle. The modified Stover-Kincannon model estimated the maximum substrate utilization rate of AnFBR's to be 196.08 gCOD/L-d, with a correlation coefficient of 0.98. Under shortended HRT, microbial diversity analysis identified predominant non-filamentous bacterial families, such as Streptococcaceae and Veillonellaceae, which collaborate during biofilm development in anaerobic environments. It was suggested that the porous media provided secure attachment sites for the biomass growth and biofilm formation under shock load and high shear force conditions. While these results offer valuable insights, further studies are needed to confirm these findings and enhance the understanding of the use porous media in non-recirculating AnFBRs.

Aerobic granular sludge sequencing batch reactor for high strength domestic wastewater treatment: Assessing kinetic models and microbial community dynamics

The study aims to treat high strength domestic wastewater (HSDW) and cultivate microbial granular sludge in a sequencing batch reactor (SBR). A bench-scale bioreactor was used for startup. Response surface methodology (RSM) was used to determine the ideal parameters for removing organic materials from HSDW. Organic loading rate (OLR) and cycle time were the independent variables taken into consideration, while the response variable was COD removal. Results from RSM revealed that the optimal conditions for achieving > 98 % COD and TP (>80) removal were a cycle length of 6 h and an OLR of 1.5 kgCOD/m3d. The Modified-Kincannon and the Grau second-order kinetic models were compared to the COD removal rate for the SBR system. The saturation rate constant (Ni) and maximal substrate removal rate (Vc) were proposed to be 6.8 g L−1 d−1 and 0.83 g L−1 d−1, respectively, based on the modified Stover-Kincannon model. The modified Stover-Kincannon (R2 = 0.93673) and Grau second order (R2 = 0.99219) models high correlation coefficient values show that the experimental results and the prediction for the microbial aerobic granular based SBR system accord well. It was discovered that the modified Stover-Kincannon model was less suitable than the Grau second order model. The system microbial community changed because of the granulation process, as the reactor design operation had a big impact on the community structure. Decreased filamentous bacteria favoured several taxa that have been found to exist in granular biomass that is appropriate for treating wastewater. This study sheds important light on the complex interactions that occur between microbial populations and operational variables all through the granulation process in SBR.

Nickel augmented biochar for sustaining produced water treatment to decarbonize oil and gas industrial waste using anaerobic-aerobic granular cylindrical periodic discontinuous batch reactors

This study assessed the efficacy of granular cylindrical periodic discontinuous batch reactors (GC-PDBRs) for produced water (PW) treatment by employing eggshell and waste activated sludge (WAS) derived Nickel (Ni) augmented biochar. The synthesized biochar was magnetized to further enhance its contribution towards achieving carbon neutrality due to carbon negative nature, Carbon dioxide (CO2) sorption, and negative priming effects. The GC-PDBR1 and GC-PDBR2 process variables were optimized by the application of central composite design (CCD). This is to maximize the decarbonization rate. Results showed that the systems could reduce total phosphorus (TP) and chemical oxygen demand (COD) by 76–80% and 92–99%, respectively. Optimal organic matter and nutrient removals were achieved at 80% volumetric exchange ratio (VER), 5 min settling time and 3000 mg/L mixed liquor suspended solids (MLSS) concentration with desirability values of 0.811 and 0.954 for GC-PDBR1 and GC-PDBR2, respectively. Employing four distinct models, the biokinetic coefficients of the GC-PDBRs treating PW were calculated. The findings indicated that First order (0.0758–0.5365) and Monod models (0.8652–0.9925) have relatively low R2 values. However, the Grau Second-order model and Modified Stover-Kincannon model have high R2 values. This shows that, the Grau Second Order and Modified Stover-Kincannon models under various VER, settling time, and MLSS circumstances, are more suited to explain the removal of pollutants in the GC-PDBRs. Microbiological evaluation demonstrated that a high VER caused notable rises in the quantity of several microorganisms. Under high biological selective pressure, GC-PDBR2 demonstrated a greater percentage of nitrogen removal via autotrophic denitrification and a greater number of nitrifying bacteria. The overgrowth of bacteria such as Actinobacteriota spp. Bacteroidota spp, Gammaproteobacteria, Desulfuromonas Mesotoga in the phylum, class, and genus, has positively impacted on granule formation and stability. Taken together, our study through the introduction of intermittent aeration GC-PDBR systems with added magnetized waste derived biochar, is an innovative approach for simultaneous aerobic sludge granulation and PW treatment, thereby providing valuable contributions in the journey toward achieving decarbonization, carbon neutrality and sustainable development goals (SDGs).

Enhancing efficiency of biological contact oxidation reactors through filaments optimization of basalt fibers bio-carriers: Insights from a pilot-scale study

There has been significant interest in using Modified basalt fibers (MBF) based bio-carriers in biological contact oxidation reactors to enhance biological remediation while minimizing secondary pollution and carbon footprints. These MBF filaments form a unique spherical structure called “bio-nest,” which supports diverse microbial communities and facilitates various biogeochemical processes. However, impact of different structural alignments of the filaments within the bio-nest on system performance has not been fully understood. To address this question, this study investigated the variable spatial structures of MBF filaments using response surface methodology. The MBF carrier media were retrofitted in a pilot-scale bio-contact oxidation reactor (R-MBF) under multiple runs, and optimal parameters for the spatial distribution were identified. The optimal parameters were identified as 17.27 cm for horizontal spacing, 15.04 cm for vertical spacing, and 62.51 % for filling ratio at 6 h of HRT. R-MBF demonstrated successful treatment performance, achieving a total nitrogen removal rate of 0.231 kg/m3/d simulated by the modified Stover-Kincannon model. Denitrifying and decarboxylating bacteria, heterotrophic nitrifying-aerobic denitrifying bacteria, ammonia-oxidizing bacteria, and nitrite-oxidizing bacteria were likely involved in pollutants transformation. The findings of the study emphasize the significance of filament optimization prior to installation as it may improve the efficiency of system's performance.

Agricultural Wastewater Treatment Using Oil Palm Waste Activated Hydrochar for Reuse in Plant Irrigation: Synthesis, Characterization, and Process Optimization

The best possible use of natural resources and the large amounts of trash produced by industrial and human activity is necessary for sustainable development. Due to the threat of global climate change and other environmental challenges, waste management systems are changing, leading to more instances of water resource management. The waste generated must be controlled from a sustainability point of view. Typically, the conventional disposal of Agricultural Wastewater (AW) and biomass can be achieved by recycling, reusing, and converting them into a variety of green products. To improve the AW quality for the purposes of environmental sustainability, Sustainable Development Goals (SDGs) 6 and 14, dealing with clean water, sanitation, and life below water, are very important goals. Therefore, the present investigation evaluates the effectiveness of a Bench-scale Activated Sludge Reactor (BASR) system for AW treatment. The BASR was designed to focus on getting the maximum possible utilization out of a biosorbent derived from oil palm waste activated hydrochar (OPAH). This is in accordance with SDG 9, which targets inorganic and organic waste utilization for added value. An experiment was developed using the Response Surface Methodology (RSM). A Hydraulic Retention Time (HRT) of 1–3 days was used in the bioreactor’s setup and operation, and Mixed Liquor Suspended Solids (MLSS) concentrations of 4000–6000 mg/L were used. BASR was fed with AW with initial mean concentrations of 4486 ± 5.63 mg/L and 6649 ± 3.48 for the five-day Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) experiments, respectively. The results obtained showed that maximum reductions of 84.66% and 72.07% were recorded for BOD5 and COD, respectively. Through RSM optimization, the greatest reductions in the amounts of organic materials were achieved with a 2-day HRT and an MLSS dosage of 5000 mg/L. Substrate elimination thresholds were assessed using the first-order, the Grau second-order, and the modified Stover–Kincannon models. The reported observations were found to be perfectly fit by the modified Stover–Kincannon model, with high R2 values of 0.9908 and 0.9931 for BOD5 and COD, respectively. As a result, the model may be used to design the BASR system and forecast how the reactor would behave. The findings from this study suggest that the developed OPAH has promising potential to be applied as eco-friendly material for the removal of BOD5 and COD from AW. Consequently, the study findings additionally possess the ability to address SDGs 6, 9, and 14, in order to fulfil the United Nations (UN) goals through 2030.

Environmental and Economic Evaluation of Downflow Hanging Sponge Reactors for Treating High-Strength Organic Wastewater

This study evaluated the performance of a downflow hanging sponge (DHS) in reducing the concentrations of chemical oxygen demand (COD), ammonia (NH3), total suspended solids (TSS), and total dissolved solids (TDS) in high-strength organic wastewater (HSOW). The DHS unit was composed of three segments connected vertically and operated under different organic loading rates (OLRs) between 3.01 and 12.33 kg COD/m3sponge/d at a constant hydraulic retention time (HRT) of 3.6 h. The results demonstrated that the DHS system achieved COD, NH3, TSS, and TDS removal efficiencies of 88.34 ± 6.53%, 64.38 ± 4.37%, 88.13 ± 5.42%, and 20.83 ± 1.78% at an OLR of 3.01 kg COD/m3sponge/d, respectively. These removal efficiencies significantly (p < 0.05) dropped to 76.39 ± 6.58%, 36.59 ± 2.91%, 80.87 ± 5.71%, and 14.20 ± 1.07%, respectively, by increasing the OLR to 12.33 kg COD/m3sponge/d. The variation in COD experimental data was well described by the first-order (R2 = 0.927) and modified Stover–Kincannon models (R2 = 0.999), providing an organics removal constant (K1) = 27.39 1/d, a saturation value constant (KB) = 83.81 g/L/d, and a maximum utilization rate constant (Umax) = 76.92 g/L/d. Adding another DHS reactor in a secondary phase improved the final effluent quality, complying with most environmental regulation criteria except those related to TDS concentrations. Treating HSOW with two sequential DHS reactors was economically feasible, with total energy consumption of 0.14 kWh/m3 and an operating cost of about 7.07 USD/m3. Accordingly, using dual DHS/DHS units to remove organics and nitrogen pollutants from HSOW would be a promising and cost-efficient strategy. However, a tertiary treatment phase could be required to reduce the TDS concentrations.

Response of dissimilatory perchlorate reducing granular sludge (DPR-GS) system to high-strength perchlorate and starvation stress in UASB reactor: Performance, kinetics and recovery mechanism

Under high-strength perchlorate concentration ranging from 300 to 1300 mg/L, the dissimilatory perchlorate reducing granular sludge (DPR-GS) was successfully cultivated in an up-flow anaerobic sludge blanket (UASB) reactor to investigate performance and starvation recovery for treating perchlorate wastewater. The mature DPR-GS had excellent perchlorate removal efficiency (98.47%) at 1200 mg/L. Microbial community analysis suggested that the dominant genera in mature DPR-GS were Sulfurospirillum and Acinetobacter. The DPR-GS system conformed well to the modified Stover-Kincannon model with the maximum substrate utilization (Umax) of 90.01 kg/(m3·d) and the saturation value constant (KB) of 83.93 kg/(m3·d). Additionally, the starvation recovery of DPR-GS system was first investigated. The perchlorate removal efficiency recovered to 91.39% after 8 days under the 30-day starvation stress, and the microbial activity also recovered to normal condition. The three-dimensional excitation-emission matrix (3D-EEM) proved that the tryptophan-like component in extracellular polymeric substance (EPS) increased during the starvation period, which was associated with immune functions and played an important role in maintaining the microbial activity. Meanwhile, the secretion of humic acid-like component in EPS promoted electron transfer efficiency, thus improving microbial metabolic activity during the recovery period. Further analysis by the parallel factor (PARAFAC) of 3D-EEM confirmed that the decrease of immune substances and the increase of metabolic products in EPS during the starvation recovery period, which enhanced the recovery of microbial activity and the improvement of perchlorate removal performance. This study revealed the response of the DPR-GS system to high-strength perchlorate and starvation stress, thus provided a further basis of perchlorate tolerance and starvation recovery for the application of DPR-GS system to remove high-strength concentrated perchlorate from contaminated water.

Variations of Organic Loading Rate on Tofu Wastewater Degradation using Upflow Anaerobic Sludge Blanket Reactor by Modified Stover-Kincannon Model

This research aims to examine the varians of organic loading rate (OLR) on degradation of tofu wastewater using the hybrid upflow anaerobic sludge blanket (hybrid UASB) reactor using the modified kinetic model of Stover Kincannon. This reactor was operated at OLRs variation of 1.5-12 kg COD m-3 d-1 and HRT of 12 - 24 hours for 328 days. Higher COD removal efficiency of 86.41% and biogas production of 7700 mL were achieved at OLR 4.8 kg COD m-3 d-1 and HRT 24 hours on 140 days. Modified Stover-Kincannon model was observed and matched data sets were obtained. The kinetic values of model obtained at HRT variations, the parameters KB and μmax were 3.7, 12.97, 2.42 mgL-1 d-1 and 0.59, 9.41, 0.014 mgL-1 d-1, respectively. This model was a plot of the inverse of the removal rate, versus inverse of the total loading rate resulted in a straight line. It showed that the Stover-Kincannon Model is the rate of substrate removal was affected by the organic load rate (OLR) that flowed into the hybrid UASB reactor.

Kinetics evaluation of a pilot scale anaerobic biofilm digester treating leachate from a municipal solid waste transfer station

In this study, leachate from municipal solid waste (MSW) transfer station was treated in a pilot scale anaerobic biofilm digester (ABD) system under 30, 25, 20 and 10-day HRT. The maximum COD concentration entering the reactor was 46,944 mg/L and the reactor was under full operation for 163 days. The results showed that COD removal efficiency was above 95 % throughout the operation and measurement of the average daily biogas production yielded a value of 25 ± 1 m3/day with a composition of 57 ± 12 % methane and 26 ± 6 % carbon dioxide. In comparison to the Monod and modified Stover–Kincannon (MSK) models, the second-order Grau model presented the best fit as a substrate-removal kinetic model for this ABD system with its R2, 0.999; while the MSK model for gas generation was proven to be a better fit than the Van der Meer and Heertjes model in predicting the amount of biogas and methane gas produced from leachate treatment via a pilot scale ABD.

Mixotrophic denitrification processes in basalt fiber bio-carriers drive effective treatment of low carbon/nitrogen lithium slurry wastewater

Lithium battery slurry wastewater was successfully treatedby using basalt fiber (BF) bio-carriers in a biological contact oxidation reactor. This resulted in a significant reduction of COD (93.3 ± 0.5 %) and total nitrogen (77.4 ± 1.0 %) at 12 h of HRT and dissolved oxygen (DO) of 0–1 mg/L. The modified Stover-Kincannon model indicated that the total nitrogen removal rate was 4.462 kg/m3/d in R-BF while the substrate maximum specific reaction rate (qmax) in the Monod model was 0.323 mg-N/mgVSS/d. A stable internal environment was established within the bio-nest. Metataxonomic analysis revealed the presence of denitrification and decarbonization bacteria, combined heterotrophic nitrification-aerobic denitrification bacteria, nitrite-oxidizing bacteria, and ammonia-oxidizing bacteria. Functional analysis displayed changes related to (aerobic)chemoheterotrophy, nitrogen respiration, nitrate reduction, respiration/denitrification of nitrite, and nitrate in R-BF. The study proposes a novel approach to achieve denitrification for the treatment of lithium slurry wastewater at low C/N conditions.

Performance and modeling studies of rotating biological contactor for treatment of vegetable oil wastewater

AbstractThis study focuses on a lab‐scale rotating biological contactor (RBC) treating vegetable oil wastewater with high BOD and COD. The fabricated RBC was checked for efficiency in degrading polluted wastewater under different operating conditions. The maximum removal efficiencies for BOD and COD were 95.75% and 89%, respectively. This high removal percentage was obtained with 30% submergence of 10 discs rotating at 8 rpm. For the first time, bio‐kinetic models were applied to the experimental results for vegetable oil wastewater. The best fit was obtained with the modified Stover‐Kincannon and Grau model. The saturation constant (Ks) values were 1.872 and 3.024 g/L/d for BOD and COD, respectively, for the modified Stover‐Kincannon and Grau model. For the Grau second‐order model, the saturation constant was 1.416 and 3.744 g/L/d for BOD and COD, respectively. The predicted effluent BOD and COD values of the modified Stover–Kincannon model fitted almost exactly with the experimental values. This clearly predicts that this model can be best used to predict effluent BOD and COD concentration in a Rotating Biological contactor treating vegetable oil wastewater. The kinetic parameters determined in this study can be used to improve the design and operation of continuous mode RBC systems.

Performance of simultaneous nitrification–denitrification and denitrifying phosphorus and manganese removal by driving a single-stage moving bed biofilm reactor based on manganese redox cycling

Simultaneous removal of NH4+-N, NO3–-N, COD, and P by manganese redox cycling in nutrient wastewater was established with a single-stage moving bed biofilm reactor (MBBR) under low C/N ratio. When sodium succinate replaced the conventional denitrifying carbon source, removal efficiencies of TN, NO3–-N, NH4+-N, TP, and Mn2+ were 65.13 %, 79.63 %, 92.79 %, 51.57 %, and 68.10 %, respectively. Based on modified Stover-Kincannon model, 11.03 and 10.05 mg TN·L−1·h−1 of Umax values were obtained with sodium acetate and sodium succinate as substrates. Extracellular polymeric substances were used to evaluate the characteristics of biofilm, and microbial community of biofilm was identified. Transformation processes of NO3–-N, NH4+-N, Mn2+, and P were investigated, suggesting that the main functional groups (e.g., CO, Mn-O, and CN bonds) participated in N, P, and Mn2+ removal, and MnO2 was the main component of biogenic manganese oxides. This study provides a new strategy for nutrients removal by Mn2+ driven MBBR.

The Biodegradation of 4-Chlorophenol in a Moving Bed Biofilm Reactor Using Response Surface Methodology: Effect of Biogenic Substrate and Kinetic Evaluation.

4-Chlorophenol (4-CP) is a persistent organic pollutant commonly found in petrochemical effluents. It causes toxic, carcinogenic and mutagenic effects on human beings and aquatic lives. Therefore, an environmentally benign and cost-effective approach is needed against such pollutants. In this direction, the chlorophenol degrading bacterial consortium consisting of Bacillus flexus GS1 IIT (BHU) and Bacillus cereus GS2 IIT (BHU) was isolated from a refinery site. A composite biocarrier namely polypropylene-polyurethane foam (PP-PUF) was developed for bacterial cells immobilization purpose. A lab-scale moving bed biofilm reactor (MBBR) packed with Bacillus sp. immobilized PP-PUF biocarrier was employed to analyse the effect of peptone on biodegradation of 4-CP. The statistical tool, i.e. response surface methodology (RSM), was used to optimize the process variables (4-CP concentration, peptone concentration and hydraulic retention time). The higher values of peptone concentration and hydraulic retention time were found to be favourable for maximum removal of 4-CP. At the optimized process conditions, the maximum removals of 4-CP and chemical oxygen demand (COD) were obtained to be 91.07 and 75.29%, respectively. In addition, three kinetic models, i.e. second-order, Monod and modified Stover-Kincannon models, were employed to investigate the behaviour of MBBR during 4-CP biodegradation. The high regression coefficients obtained by the second-order and modified Stover-Kincannon models showed better accuracy for estimating substrate degradation kinetics. The phytotoxicity study supported that the Vigna radiata seeds germinated in treated wastewater showed higher growth (i.e. radicle and plumule) than the untreated wastewater.

Kinetics of Pulp and Paper Wastewater Treatment by High Sludge Retention Time Activated Sludge Process

Paper and pulp industrial processes lead to the discharge of wastewater that contains high pollutants concentrations into the environment, which subsequently contaminate freshwater. Thus, it necessitates a sustainable treatment approach. This study focused on the start-up of the bench-scale activated sludge system fed with pulp and paper wastewater to verify the influence of HRT, wastewater concentration, and sugarcane bagasse on COD and ammonia removal efficiencies during the treatment process. An activated sludge process was operated at a flow rate of 5 L/day, while the reactor kept running at 72 h, 48 h, and 24 h HRT, respectively. Wastewater concentrations were set at 1039, 3158, 5248 mgCOD//L and 13.74, 40.37, 67.04 mgNH4+-N/L corresponding to 10, 50 and 100% respectively. Findings revealed high removal efficiencies up to 98.11% and 92.67% for COD and ammonia, respectively. After treatment, effluent concentrations for both parameters have satisfactorily met the Standard "A" standard limits for industrial discharge at 48 hours HRT. Therefore, further testing is not required. The First order and Modified Stover-Kincannon models evaluated substrate removal rates. In the Modified Stover–Kincannon model, high correlation coefficients R2 of 0.9999 and 0.9998 were obtained for COD and ammonia, respectively. Unfortunately, the activated sludge process in the bioreactor could not be described by the first-order kinetic model. The modified Stover-Kincannon model proved to best suit the experimental data.

Parametric optimization and kinetic modelling for organic matter removal from agro-waste derived paper packaging biorefinery wastewater

The state-of-the-art paper packaging biorefinery utilizes cellulose fibrous material from paddy straw and papaya latex to produce packaging products. This in turn generate wastewater with high organic matter content that if disposed without treatment will pollute water bodies and affect aquatic life below water. Therefore, to comply with “clean water and sanitation” (SDG 6) and “life below water” (SDG 14), this study assesses the efficacy of an extended aeration activated sludge (EAAS) in the treatment of paper packaging biorefinery wastewater (PPBW) by employing paddy straw-derived activated carbon as a biosorbent. Findings revealed that the system was able to achieve 95–98.2% and 90.62–94.96% biological oxygen demand (BOD5) and chemical oxygen demand (COD) reduction, respectively. The maximum organic matter removals were achieved at 2-day hydraulic retention time (HRT) and 60% PPBW concentration. To evaluate substrate removal rates, the first-order, modified Stover–Kincannon and Grau second-order models were used. In the modified Stover–Kincannon model, high correlation coefficients values R2 of 0.99986 and 0.99991 were obtained for COD and BOD5, respectively. Twenty grams COD/L/day and 50 gBOD5/L/day were obtained as Umsr for COD and BOD5, respectively, and 20.402 g/L/day and 56.295 g/L/day as KV constants for COD and BOD5, respectively. The COD and BOD5 biokinetic constant values for the Grau second-order organic matter removal rate constant kS were 36 day−1 and 0.78 day−1, respectively. Here, 0.9989 and 0.99928 were the obtained R2 values for COD and BOD5, respectively. The EAAS bioreactor system described by modified Stover–Kincannon model was proven to best suit the experimental data. Therefore, the model can be used in designing an EAAS system and consequently predict the bioreactor behaviour. The result of this study provided a benchmark for the actual implementation of PSAC in PPBW treatment for COD and BOD5 removal. It has been proven that PSAC biosorbent sourced from a natural agro-waste material is essential and could be used as an efficient substance for organic matter removal. Operating expenses and associated savings were such that PASC was more attractive in an economic analysis of wastewater treatment demands. It is environmentally benign and offers a green treatment option to the PPBW. It could be an alternative to chemical materials because it is harmless to human health and proffer sustainable solution to potable water production.

Which kinetic model best fits the methane production on pig farms with covered lagoon digesters?

The volumetric production of biogas can be estimated through kinetic models, although many of them have not been validated adequately in full-scale systems with specific operational conditions in tropical countries. This study aimed to evaluate the applicability of these kinetic models to estimate methane production in pig farming operated with covered lagoon digesters (CLD, to inform: Chen-Hashimoto, First-order, Cone, Modified Gompertz, Modified Stover-Kincannon and Deng. The input data were obtained through the monitoring of two CLD in pig farming located in Minas Gerais-Brazil. The analyzed parameters were methane composition, the temperature of the substrate, chemical oxygen demand (COD), and volatile solids. The real production of methane (Pactual) was determined in relation to the electric power production at the internal combustion engine. The results obtained for Pactual and the models were compared through regression analysis (t-test, α=1%). All of the evaluated models overestimate the methane production in comparison with Pactual (405.0 m3 CH4 d-1). The smallest difference between the CH4 production and the measurement on the pig farm was obtained with Chen model, overestimating approximately 16.3%, while the highest estimate was 38.5% obtained with the Modified Stover-Kincannon model. The results showed the absence of statistical differences among the real data (monitored system) and the simulated data (p-value>0.01). The mathematical kinetic models are considered a reliable tool to evaluate the energetic potential of biogas in pig farming with CLD from operational simplicity and low cost.

Performance evaluation and substrate removal kinetics in a thermophilic anaerobic moving bed biofilm reactor for starch degradation

Abstract A laboratory-scale anaerobic moving bed biofilm reactor (AnMBBR) was installed and operated at various hydraulic retention times (HRTs) of 20 to 1.5 d with surface area loading rate (SALR) of 0.86 to 11.43 gCOD/m2/d. Synthetic starch containing desizing wastewater with chemical oxygen demand (COD) of 12.75 g/L was prepared and fed into the reactor. Monod, modified Stover-Kincannon, Grau second-order and First-order substrate removal models were used to evaluate the results of AnMBBR. COD removal efficiency of bioreactor was dwindled by increasing the SALR or reducing the HRT. Decay coefficient (Kd) and yield coefficient (Y) for the Monod model were 0.027 1/d and 1.01 mgVSS/mgCOD, respectively. Maximum substrate utilization rate (Umax) and kinetic constant (Kb) for the Modified Stover-Kincannon model were estimated as 12.57 and 15.22 g/L/d, respectively. The constants (a and b) for the Grau second-order model were found to be 1.09 and 1.31 whilst kinetic coefficient for the Second-order model and First-order substrate removal model were 1.62 and 1.55 1/d, respectively. Modified Stover-Kincannon model and Grau second-order model were found to be the best fit for experimental data with R2 value of 0.99. The findings suggest that these models can be applied to predict the behaviour of AnMBBRs on various scales.

Bioelectrochemical system for anaerobic oily wastewater treatment: Biokinetic & energy consumption studies

The present study introduced a laboratory-scale, anaerobic treatment system for the removal of oil from synthetic wastewater using a biofilm-electrode reactor (BER). The operating parameters of current intensity, initial concentration, reaction time, and supporting electrolyte were investigated. The results of the present study showed that the optimal conditions were: a current intensity of 15 mA, COD concentration of 1500 mg L−1, a reaction time of three days, and 150 mg L−1 NaCl as a supporting electrolyte. The highest efficiency for the COD removal was 86.7% using the introduced method, while it was 65.9% using general biological processes. In the present study, the energy consumed by the bioelectrochemical system was 1.914 kWh/m3. The biokinetic study indicated that the removal reaction was more consistent with the modified Stover-Kincannon model. The present study indicated that BER is a promising method for the treatment of oil-contaminated wastewaters. It is expected that experimental results will be used as a reference for advance bio-treating of oily wastewater.

Start-up performance and process kinetics of a UASB-Anammox reactor at low substrate concentration

In this study, the start-up performance and process kinetics of a UASB-Anammox reactor with nitritation sludge at low substrate concentration were evaluated. The results demonstrated that the UASB-Anammox reactor was successfully started by inoculating with a mixture of nitritation sludge and anaerobic ammonium oxidation granular sludge. After 120 days of operation, good nitrogen removal was obtained by anaerobic ammonia oxidation(Anammox). During start-up and operation of the system, TN load removal exhibited an "S-shape" curve. An analysis using microbial growth kinetics models showed that the Logistic Model, the Modified Logistic Model, the Modified Gompertz Model and the Modified Boltzmann Model could all describe the experimental data of TN removal. The process kinetics analysis also showed that nitrogen removal by the UASB-Anammox reactor operating under steady-state conditions can be simulated using the Grau Second-Order Model and the Modified Stover-Kincannon Model. Parameters obtained from the model analysis facilitate the prediction of nitrogen removal performance, operation management and control of similar reactors.