Primary Clarifier Research Articles

Optimal-Setpoint-Based Control Strategy of a Wastewater Treatment Process

This paper presents an optimal-setpoint-based control strategy of a wastewater treatment process (WWTP). The treatment plant serves the city of Galati, located in Eastern Romania, a city with a population of 250,000 inhabitants. As the treatment plant includes several control loops (based upon PI controllers), an efficient operation means the establishing of an optimal operating point regardless of the pluviometric regime (DRY, RAIN and STORM) or transitions between regimes. This optimal operating point is given by the optimal setpoint set (setpoints of the dissolved oxygen concentration in the aerated tanks, setpoint of the nitrate concentration, external recirculation flow, sludge flow extracted from the primary clarifier and excess sludge flow from the secondary clarifier) of the treatment plant control loops. The control algorithm has two distinct parts: the first part consists of computing the optimal aforementioned setpoints, based on the mathematical model of the treatment plant developed in SIMBA. For optimization (performed with genetic algorithms) an aggregate performance criterion that takes into consideration the quality of the effluent, the cost of the wastewater treatment as well as the percentage exceeding of the main parameters of the treated water was used; the second part consists of computing the optimal setpoint set which will be further applied directly in the process based on the membership to the current operating regime. The computation of the membership degrees to the current operating regime was performed with a fuzzification block, based on the information about the inflow rate in the biological treatment plant. For simulations, three data files of the influent were created, aiming at determining the optimal setpoints in each operating regime, and a fourth one containing an influent scenario able to globally test the system operation. The obtained results showed the efficiency of the biological treatment, the effluent quality index being about ten times lower than that of the influent. Furthermore, the genetic algorithm used in optimization determines accurately enough the minimum value of the performance criterion in the case of each pluviometric regime, the lowest value of the performance criterion being obtained in DRY operating regime and the highest values in RAIN and STORM regimes. This is mainly due to the increase of the treatment cost and to small exceeding of the limits of several quality parameters such as chemical oxygen demand and ammonium concentration in the two regimes mentioned above. The fuzzification block aims to achieve a smooth transition from one operating regime to another, thus determining easier operating regimes of the treatment plant actuators and contributing to the increase of their life cycle.

Anaerobic digestibility of resin acids in primary sludge: Effect of ozone pretreatment

Resin acids in pulp and paper mills wastewater are potentially partitioned in the solids in post–primary clarification due to higher hydrophobicity with log Kow ∼1.74–5.80. They are known to adversely affect anaerobic digestion (AD) process, although the effect has not been quantified deterministically in control studies. The objective of the present work was to determine the effect of untreated and ozonated spiked resin acids on AD of primary sludge. Batch adsorption tests were conducted to determine the solid-liquid partition coefficient (Kd) of resin acids on the primary sludge. Higher Kd was obtained at pH 4; however, it was decreased by 78–98% at pH 8. Thereafter, batch AD of model resin acids in primary sludge using food to microorganism ratio (S0/X) of 0.5gtCOD/gVSSindicated only 15–20% removal of resin acids in the liquid phase anaerobically. While, ozonation in pure water using 0.74–1.48 mg O3/mg tCOD showed >90% reduction of the test resin acids, an ozone dose of 0.52 mg O3/mg tCOD reduced 50–70% spiked resin acids’ load to the digester. However, no further removal of resin acids occurred during AD over 30 days. About 42% reduction in methane production compared to the control digestor occurred in the presence of 150 mg/L of resin acids. When treated with 0.52 mg O3/mg tCOD, methane production improved and was comparable to the control digestor, indicating that resin acids may not be detrimental to AD at a concentration range of 45–75 mg/L.

Innovative Rough Beer Conditioning Process Free from Diatomaceous Earth and Polyvinylpolypyrrolidone.

In large-sized breweries, rough beer clarification is still carried out using Kieselguhr filters notwithstanding their environmental and safety implications. The main aim of this work was to test an innovative rough beer clarification and stabilization process involving enzymatic treating with Brewers Clarex®, centrifuging, rough filtering across 1.4-μm ceramic hollow-fiber membrane at 30 °C, and fine filtering through 0.45-μm cartridge filter. When feeding an enzymatically-pretreated and centrifuged rough beer with permanent haze (HP) of 2 or 14 European Brewery Convention unit (EBC-U), its primary clarification under periodic CO2 backflushing yielded a permeate with turbidity of 1.0–1.5 EBC-U at a high permeation flux (2.173 ± 51 or 593 ± 100 L m−2 h−1), much greater than that typical of powder filters. The final beer was brilliant (HP = 0.57 ± 0.08 EBC-U) with almost the same colloidal stability of the industrial control and an overall log reduction value (~5.0 for the selected beer spoilage bacterium or 7.6 for the brewing yeast) in line with the microbial effectiveness of current sterilizing membranes. It was perceived as significantly different in flavor and body from the industrial control at a probability level of 10% by a triangle sensory test, as more likely related to the several lab-scale beer-racking steps used than to the novel process itself.

Factors affecting microplastic retention and emission by a wastewater treatment plant on the southern coast of Caspian Sea

Understanding how wastewater treatment plants (WWTPs) process microplastics (MPs) will help informing management practices to reduce MP emissions to the environment. We show that composite 24 h samples taken at three replications from the outflow of the grit chamber, primary settling tank and clarifier of the WWTP of Sari City, on the southern coast of the Caspian Sea, contained 12667 ± 668, 3514 ± 543 and 423 ± 44.9 MP/m3, respectively. Fibers accounted for 94.9%, 89.9% and 77.5% of the total number of MPs, respectively. The MP removal efficiency was 96.7%. MP shape (fiber, particle), size and structure were the most important factors determining their removal in different steps of the wastewater treatment process. The structure of microfibers (polyester, acrylic and nylon) and the consequent higher density than water explained their high removal (72.3%) in the primary settling tank. However, size was more important in microparticle removal with particles ≥500 μm being removed in the primary settling tank and <500 μm in the clarifier unit. The smallest particles (37–300 μm) showed the lowest removal efficiency. The predominant types of fibers and particles were polyester and polyethylene, respectively, which are likely to originate from the washing of synthetic textiles and from microbeads in toothpaste and cosmetics. Despite the efficiency of the Sari WWTP in removing MPs, it remains a major emission source of MPs to the Caspian Sea due to its high daily discharge load.

Investigating the dynamics of volatile sulfur compound emission from primary systems at a water resource recovery facility.

This study quantifies volatile sulfur compound (VSC) emissions from primary settling tanks and investigates their mechanisms of generation. Hydrogen sulfide (H2 S) and methyl mercaptan (MM) concentrations in the off-gas were dominant among the VSCs analyzed, while dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) were under their odor threshold for most sampling dates. H2 S emission in primary settling tanks was mainly the result of the stripping of dissolved sulfide (64%) generated in the sewers. Results indicate that MM emission was more dependent on the conditions in the primary clarifiers (only 16% stripping). Prevention of odor emission in primary settling tanks can be achieved by managing biofilms and microbial reactions in the sewer network. Controlling the biomass seeding and fermentation product availability in the primary settling tanks is essential to significantly minimize the kinetics of H2 S and MM generation. Overall, the management of sludge blanket heights and thus avoiding time at low oxidation-reduction potential minimized odor emission independent of sewer conditions. PRACTITIONER POINTS: H2 S emission from primary clarifiers mainly originated from the stripping of the dissolved sulfide formed in the sewers. MM emission contributed for 89% to overall odor emitted from primary clarifiers. Seeding of active biomass from the sewer into the primary clarifiers was be the main driver for both MM and H2 S formation. Increased availability of fermentation products or fermenters increased MM production.

Acceleration of the particulate organic matter hydrolysis by start-up stage recovery and its original microbial mechanism

To address the availability of carbon sources for denitrification, the accelerated hydrolysis of the most abundant but low-availability fraction of particulate organic matter (POM) was investigated. Mesh sieves with different pore sizes were used as primary pretreatment at the start-up-stage of the biological process to separate some POM from the liquid system. The changes in soluble carbohydrates and proteins were monitored to investigate the hydrolysis performance of the sieved POM, with waste activated sludge (WAS) as the control test. The results showed that an average of 35% POM could be entrapped before filtrate mat development. In addition, benefiting from the high polysaccharides concentration, as well as the high availability due to the relatively loose physical structure, a 23% hydrolysis efficiency of POM was obtained, in contrast to that of WAS (3.4%), with a hydrolysis constant of 0.39 h−1. The prominent performance was also attributed to the unique microbial communities having been domesticated at a lower temperature, especially the cellulose-degrading bacteria Paraclostridium and psychrophile Psychrobacter, making up 6.94% and 2.56%, respectively. Furthermore, the potential benefits and application of improved POM hydrolysis by start-up stage recovery via mesh sieves combined with anaerobic fermentation were evaluated, including selective POM entrapment, alleviation of blockage and wear, and a reduction in aeration energy. By the proposed strategy, carbon availability for biological nutrient removal (BNR) processes is anticipated to be improved more economically than that can be achieved by primary clarifier elimination.

Effect of F/M Ratio on the Performance of Sequencing Batch Reactor for Dairy Wastewater Treatment

Indian economy has huge contribution of dairy industry. About one fourth of nation’s income is contributed by dairy. Milk processing involves various operations starting from receiving point to disposal end. This whole process demands fresh water leading to wastewater generation and this quantity is highest amongst all industries. Dairy wastewater is composed of organic matter, nutrients, suspended & dissolved solids and high COD, BOD. So it becomes necessary to remove the pollution load before its disposal. Some advanced treatments like SBR, gas stripping, surface filtration show better results and are effective than conventional treatments. In this study, SBR process was used to treat dairy wastewater. SBR process has flexibility, minimal footprint and it conducts all operations like equalization, primary clarification, biological treatment and secondary settling in a single reactor. Time phased Fill and draw type lab scale SBR model was operated with 12 liter total volume and 10 liter working volume. Before loading dairy wastewater to the reactor, loading of sewage was done for acclimatization of microorganisms. Dairy wastewater was collected from equalization tank of an Effluent Treatment Plant of dairy industry. It was analysed for various parameters for 15 days to know the variations in characteristics. For the treatment of dairy wastewater reactor was operated under varying MLSS from 6000 to 8000 mg/L thereby under varying F/M ratio and named as phase 1, phase 2, and phase 3 with 20% Volume Exchange Ratio. Total cycle time provided was 6 hour in which fill was instantaneous, aeration for 5 hour 30 minutes, settling for 25 minutes and 5 minute decant. By keeping all the remaining parameters constant, only F/M ratio was varied. Maximum removal efficiencies for parameters like COD, BOD, TDS, and TSS were determined for each phase. For phase 1, 2 and 3 maximum removal efficiencies were achieved at F/M 0.16, 0.14 and 0.13 per day respectively. But among all three phases, 3rd phase gave maximum removal efficiency at F/M 0.13. Hence it was concluded that SBR performs better at higher MLSS concentration or at lower F/M ratio in order to achieve disposal standards.

Automation of Dead End Filtration: An Enabler for Continuous Processing of Biotherapeutics.

Dead end filtration is a critical unit operation that is used for primary and secondary clarification during manufacturing of both microbial and mammalian cell based biotherapeutics. Dead end filtration is conventionally done in batch mode and requires filter pre-sizing using extensive scouting studies, along with filter over-sizing before deployment to handle potential variability. However, continuous manufacturing processes require consistent use of dead-end filtration over weeks or months, with potential unpredictable variations in feed stream attributes, which is a challenge currently facing the industry. In this work, a dead-end filtration skid is designed for continuous depth filtration, incorporating multiple small-sized filters along with turbidity, and pressure sensors with immediate switching to a fresh filter whenever turbidity or pressure breakthrough above a pre-determined cut-off is detected in real time. The skid has been successfully tested for manufacturing of granulocyte colony stimulating factor from Escherichia coli, human serum albumin from Pichia pastoris, and a monoclonal antibody therapeutic from CHO cells. The proposed skid can be directly applied for any dead-end filtration application with minimal prior scouting studies or sizing calculations for scale-up. It is a useful solution for continuous processing trains where the nature of the feed, such as its turbidity or host cell proteins content, may change over long continuous campaigns, rendering previous sizing calculations inaccurate. The skid also allows significant cost savings by eliminating the sizing safety factor of 1.5–2x which is generally added before filter deployment at manufacturing scale.

Comparison of sensor driven aeration control strategies for improved understanding of simultaneous nitrification/denitrification.

A pilot scale process was operated with A-stage effluent (ASE) and primary clarifier effluent (PCE) in MLE, all tanks aerated, A/O, and A2O configurations. Continuous DO control at high DO (2mg/L), low DO (0.1-0.3mg/L), ammonia-based aeration control (ABAC), and ammonia versus NOx (AvN) control (both continuous and intermittent operation) were compared on the basis of total inorganic nitrogen (TIN) removal, and simultaneous nitrification-denitrification (SND). The highly loaded adsorption/bio-oxidation (A/B) process configuration (4hr HRT) with intermittent aeration was capable of achieving a maximum TIN removal of 80%, while the A2O process with PCE feed, an 11hr HRT, and 0.2-0.3mg/L DO continuous aeration achieved a maximum of 88% TIN removal. ABAC and AvN control did not always result in DO setpoints low enough to achieve SND, and even if setpoints were low enough to achieve SND that did not always result in increased overall TIN removal over continuous DO control of 2mg/L. While there are other benefits to transitioning to sensor driven aeration control strategies such as ABAC and AvN, increased TIN removal during continuous aeration is not guaranteed. Results suggest that although low DO is a prerequisite for SND, carbon availability for denitrification in the aerobic zone is more likely to be the limiting factor once low DO conditions are met. PRACTITIONER POINTS: Intermittent aeration control results in higher TIN removal than continuous aeration at the same total SRT Continuous aeration AvN control is not likely to result in more TIN removal than continuous aeration ABAC for a given COD and nitrogen load Configurations that are designed to maximize predenitrification (e.g., MLE and A2O) are less likely to achieve increased SND in the aerobic zone from low DO operation than configurations that are not (e.g., A/O).

Primary Clarification of CHO Harvested Cell Culture Fluid using an Acoustic Separator.

Primary clarification is an essential step in a biomanufacturing process for the initial removal of cells from therapeutic products within the harvested cell culture fluid. While traditional methods like centrifugation or filtration are widely implemented for cell removal, the equipment for these processes have large footprints and operation can involve contamination risks and filter fouling. Additionally, traditional methods may not be ideal for continuous bioprocessing schemes for primary clarification. Thus, an alternate application using acoustic (sound) waves was investigated to continuously separate cells from the cell culture fluid. Presented in this study is a detailed protocol for using a bench-scale acoustic wave separator (AWS) for the primary separation of culture fluid containing a monoclonal IgG1 antibody from a CHO cell bioreactor harvest. Representative data are presented from the AWS and demonstrate how to achieve effective cell clarification and product recovery. Finally, potential applications for AWS in continuous bioprocessing are discussed. Overall, this study provides a practical and general protocol for the implementation of AWS in primary clarification for CHO cell cultures and further describes its application potential in continuous bioprocessing.

Primary Clarification of CHO Harvested Cell Culture Fluid using an Acoustic Separator

Primary Clarification of CHO Harvested Cell Culture Fluid using an Acoustic Separator

Assessing the potential of enhanced primary clarification to manage fats, oils and grease (FOG) at wastewater treatment works

Daily, sewage treatment works (STWs) receive large volumes of fats, oils and greases (FOG), by-products of food preparation. To increase FOG removal at STW, conventional primary sedimentation tanks (PSTs) can be enhanced using chemical coagulant or through dissolved air flotation (DAF) techniques. This work aimed to assess the potential benefits of enhanced primary treatment for FOG removal through an energy and costs analysis. To achieve this, a five-year sampling programme was conducted monthly at 15 STWs measuring FOG concentrations in crude and settled sewage (i.e. after primary treatment). In addition, two DAF pilot systems were trialled for four months and their performance, in terms of FOG removal, was assessed and compared to that of a control primary clarifier. Across the 15 STWs, influent FOG concentrations were found at 57 ± 11 mg.L−1. Chemical coagulants dosed prior to PSTs increased FOG removal rates on average to 71% whilst traditional sedimentation only achieved 50% removal. Effluent FOG concentrations were found between 12–22 mg.L−1 and 19–36 mg.L−1 respectively. By contrast, DAF achieved FOG effluent concentrations on average at 10 ± 4 mg.L−1 corresponding to 74% removal from a relatively low influent concentration of 40 ± 30 mg.L−1. Thus, enhanced primary treatments have the potential to reduce organic load to secondary treatment and increase energy generation through anaerobic digestion. The overall net energy balance was estimated at 2269 MWh.year−1 for the DAF compared to 3445 MWh.year−1 for the chemically-enhanced PST making it a less financially attractive alternative. Yet, in the case where the works require upgrading to accommodate flow or load increases, DAF appeared as a sensible option over sedimentation offering significantly lower capital costs and footprint. In relation to FOG management, upgrading all STWs is not realistic and will require understanding where the benefits would be the highest.

Water Hyacinths–biomass Production Potential at a Waste Water Treatment Plant

The growth of Eichhornia crassipes under outdoor conditions was examined during a 42-day test in a wastewater treatment plants primary clarifier, trickling filter and secondary clarifier using municipal residential wastewater as the chosen supplier of nutrients.&#x0D; Test results showed that Eichhorn crassipes plants gained a significant amount of biomass in a short period. Plants could increase their biomass 15.1-fold from the initial weight of 457.6 g to 6898.8 g for the primary clarifier and 12.6-fold from the initial weight of 288.2 g to 3635.0 g for the secondary clarifier. Plant growth in the trickling filter was limited by factors such has as observed bird picking, Cladophra algae growth in the trickling filter and on the roots of Eichhorn crassipes, and intermittent exposure to nutrients contained in the municipal residential wastewater.

Challenges of arsenic removal from municipal wastewater by coagulation with ferric chloride and alum

Discharge of treated municipal wastewater containing arsenic (As) may cause adverse effects on the environment and drinking water sources. Arsenic concentrations were measured throughout the treatment systems at two municipal wastewater plants in New Jersey, USA. The efficiency of As removal by ferric chloride and alum coagulants were evaluated. Besides, the effects of suspended solids in the mixed liquor, pH, and orthophosphate (PO43−) on As removal were investigated. The total recoverable As (TAs) concentrations in the influent and effluent of Plant A were in the ranges of 2.00–3.00 and 1.50–2.30 μg/L, respectively. The results indicated that <30% of the As was removed by the conventional biological wastewater treatment processes. The influent and effluent TAs concentrations at Plant B was below 1.00 μg/L. The bench-scale coagulation results demonstrated for the first time that the coagulation treatment could not effectively remove As from the municipal wastewater to <2.00 μg/L. Very high doses of the coagulants (8 and 40 mg/L of Fe(III) or Al(III)) were required to reduce the TAs from 2.84 and 8.61 μg/L in the primary clarifier effluent and arsenate-spiked effluent samples to <2.00 μg/L, respectively, which could be attributed to the high concentrations of PO43− and dissolved organic matters (DOM) in the wastewater. The protein DOM in wastewater may negatively impact removal efficiencies more than the DOM in natural water, which mainly consists of humic substances. Furthermore, an artificial neural network was constructed to determine the relative importance of different parameters for As removal. Under the experimental conditions, the importance followed the order: coagulant dose>dissolved PO43− > initial As concentration > pH. The findings of this study will help develop effective treatment processes to remove As from municipal wastewater.

Daily influent variation for dynamic modeling of wastewater treatment plants

Wastewater treatment plants (WWTPs) with activated sludge system are widely used throughout the most common technologies in the world. Most treatment plants require optimization of certain treatment processes using dynamic modeling. A lot of examples of dynamic simulations require reliable data base of diurnal variation of the inflow and typical concentrations of parameters such as Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN), etc. Such detailed data are not available, which leads to problems in the application of dynamic simulations. In many examples of plants, continuous flow measurements are only performed after the primary clarifier, whereas measurements from influent to the plant are missing, as is the case with the examples in this paper. In some cases, a simpler, faster and cheaper way can be applied to determine influent variations, such as the „HSG-Sim” method (“Hochschulgruppe Simulation”). “Hochschulgruppe Simulation” is a group of researchers from Germany, Austria, Switzerland, Luxembourg, Netherlands and Poland (see http://www.hsgsim.org). This paper presents a model for generating daily variations of inflow and concentration of municipal wastewater quality parameters, applied to several existing WWTPs in Bosnia and Herzegovina (B&H). The main goal of the applied method is to generate realistic influent data of the existing plants in B&H, in terms of flow and quality, without any prior comprehensive survey and measurements at the site. The examples of plants show the influence of overflow facilities on the dynamics of input flow and quality of wastewater, and a strong influence of the problems of the sewerage systems.

Full-scale investigation of ferrous dosing in sewers and a wastewater treatment plant for multiple benefits

This study demonstrates the full scale application of iron dosing in a metropolitan wastewater treatment plant (WWTP) and the upstream sewer system for multiple benefits. Two different dosing locations, i.e., the WWTP inlet works (Trial-1) and upstream sewer network (Trial-2) were tested in this study. Both dosing trials achieved multiple benefits such as sulfide control, phosphate removal and improved sludge dewaterability. During Trial-1, a sulfide reduction of >90% was achieved at high dosing rates (>19 kgFe ML−1) of ferrous chloride in the inlet works and in Trial-2 the in-sewer ferrous dosing had significant gas phase hydrogen sulfide (H2S) concentration reduction in the sewer network. The ferrous dosing enhanced the phosphate removal in the bioreactor up to 76% and 53 ± 2% during Trial-1 & 2, respectively. The iron ending up in the anaerobic sludge digester reduced the biogas H2S concentration by up to 36% and 45%, respectively. The dewaterability of the digested sludge was improved, with relative increases of 9.7% and 9.8%, respectively. The presence of primary clarifier showed limited impact on the downstream availability of iron for achieving the afore-mentioned multiple benefits. The iron dosing enhanced the total chemical oxygen demand removal in the primary clarifier reaching up to 49% at the high dose rates during Trial-1 and 42 ± 1% during Trial-2. This study demonstrated that multiple benefits could be achieved independent of the iron dosing location (i.e., at the WWTP inlet or in the network). Further, iron dosing at both locations enhances primary settling, beneficial for bioenergy recovery from wastewater.

Prediction of total suspended solids present in effluent of primary clarifier of industrial common effluent treatment plant: Mechanistic and fuzzy approach

Primary clarifier plays vital role in removal of pollutants present as total suspended solids (TSS) in wastewater. In this research work prediction of effluent TSS present in the sedimentation tank of clariflocculator is reported. The data of common effluent treatment plant (CETP), Ahmedabad, India has been used in the development of soft sensor. The mechanistic and fuzzy inference system (FIS) soft sensor models have been developed. The models predict the effluent total suspended solids (TSSe) of clariflocculator process based on the measurement of influent flow rate (Qf) and influent total suspended solids (TSSin). The root mean square error (RMSE) of mechanistic model and fuzzy inference system were 30 and 48 respectively for the data samples Qf ranging from 800 to 900 m3/h and TSSin from 300–600 mg/L. These ranges are typically observed throughout the year at CETP, Ahmedabad, India. The percentage mean accuracy for mechanistic model was 88 %. The difference between predicted and actual measured values of RMSE and percentage mean accuracy of mechanistic model is acceptable as system is highly sensitive. Mechanistic model gives information of total suspended solids present in retentate as well as TSS present at different height of the sedimentation tank in addition to TSS present in effluent.

Dynamic model validation and advanced polymer control for rotating belt filtration as primary treatment of domestic wastewaters

Rotating belt filters are a primary treatment technology currently used in municipal wastewater treatment plants as a high-rate alternative to primary clarifiers. Such systems are reported to efficiently remove particulates in the form of total suspended solids, achieving the highest removal efficiencies (>60%) when polymer is added as pre-treatment step. In this paper, a new dynamic model describing the RBF performance is presented. The model includes the dynamic effects of influent flow rate and TSS concentration and can also describe the effects of polymer dosing on RBF performance. The validated model was used to perform a plant-wide impact assessment using the Benchmark Simulation Model n.2. For a TSS removal efficiency that is identical to primary clarifiers (50%), rotating belt filters were found to only slightly decrease the aeration energy demand in the activated sludge unit (−0.5%), while increasing methane production and slightly increasing effluent TN concentrations (+1.5% and +1.9%, respectively). Furthermore, considerable savings in polymer costs could be attained using an advanced control strategy for polymer dosing, successfully tested in this work.

Energetic refurbishment of an existing large-scale MBR

Abstract Operations of an existing municipal MBR serving 80,000 inhabitants were improved energetically by implementing new automation routines for biology and membrane filtration. Finally, the MBR was refurbished by adding primary clarification and anaerobic sludge digestion to the treatment process, while specific energy consumption was reduced by one third to 0.65 kWh/m3 permeate produced. A combined heat and power engine generates electrical power on site from digester gas. The projected carbon footprint of plant operations will thus be halved by reducing indirect emissions from electricity consumption.

The Effect of Total Suspended Solids on the Electricity Generation in Microbial Fuel Cell Treating Actual Potato Chips Processing Wastewater

This study aimed to investigate the effect of total suspended solids (TSS) on the performance of a continuously operated dual-chamber microbial fuel cell (MFC) proceeded by primary clarifier to treat actual potato chips processing wastewater. The system was also tested in the absence of the primary clarifier and the results demonstrated a significant effect of TSS on the polarization curve of the MFC which was obtained by operating the graphite anodic electrode against Ag/AgCl reference electrode. The maximum observed power and current densities were decreased form 102.42 mW/m2 and 447.26 mA/m2 to 80.16 mW/m2 and 299.10 mA/m2, respectively due to the adverse effect of TSS. Also, the internal resistance increased from 40 to 70Ω.&#x0D;