Sustainable Agro-Food Industrial Wastewater Treatment Using High Rate Anaerobic Process

This review article compiles the various advances made since 2008 in sustainable high-rate anaerobic technologies with emphasis on their performance enhancement when treating agro-food industrial wastewater. The review explores the generation and characteristics of different agro-food industrial wastewaters; the need for and the performance of high rate anaerobic reactors, such as an upflow anaerobic fixed bed reactor, an upflow anaerobic sludge blanket (UASB) reactor, hybrid systems etc.; operational challenges, mass transfer considerations, energy production estimation, toxicity, modeling, technology assessment and recommendations for successful operation

Sustainable Agro-Food Industrial Wastewater Treatment Using High Rate Anaerobic Process

This review article compiles the various advances made since 2008 in sustainable high-rate anaerobic technologies with emphasis on their performance enhancement when treating agro-food industrial wastewater. The review explores the generation and characteristics of different agro-food industrial wastewaters; the need for and the performance of high rate anaerobic reactors, such as an upflow anaerobic fixed bed reactor, an upflow anaerobic sludge blanket (UASB) reactor, hybrid systems etc.; operational challenges, mass transfer considerations, energy production estimation, toxicity, modeling, technology assessment and recommendations for successful operation

Sustainable Agro-Food Industrial Wastewater Treatment Using High Rate Anaerobic Process

This review article compiles the various advances made since 2008 in sustainable high-rate anaerobic technologies with emphasis on their performance enhancement when treating agro-food industrial wastewater. The review explores the generation and characteristics of different agro-food industrial wastewaters; the need for and the performance of high rate anaerobic reactors, such as an upflow anaerobic fixed bed reactor, an upflow anaerobic sludge blanket (UASB) reactor, hybrid systems etc.; operational challenges, mass transfer considerations, energy production estimation, toxicity, modeling, technology assessment and recommendations for successful operation

Energy Recovery Through Biohydrogen Production for Sustainable Anaerobic Waste Treatment: An Overview

The paper is a comprehensive review of the literature for the last five years to provide the current status of H2 production through anaerobic digestion of industrial waste. Hydrogen production through dark fermentation is still far from industrial application. More research is needed to overcome the metabolic limitation and increase H2 yield, rate, and substrate-to-H2 conversion efficiency in a stable process. Generally, studies on effects of culture pretreatment are contradictory and lacked energy and cost analysis in their evaluation. More studies are expected to appear on two-stage and integrative systems of various H2 and other biofuels or value-added chemicals bioprocesses. Metabolic modelling, metabolic engineering, and molecular biology aspects of the microbial community are the current research areas for H2 production through dark fermentation and a coordinative research agenda is required to integrate them into a goal-directed plan. Investment and funding of research are the major drives needed to achieve a milestone

Impact of Organic Loading Rate on Psychrophilic Anaerobic Digestion of Solid Dairy Manure

Increasing the feed total solids to anaerobic digester improves the process economics and decreases the volume of liquid effluent from current wet anaerobic digestion. The objective of this study was to develop a novel psychrophilic (20 °C) anaerobic digestion technology of undiluted cow feces (total solids of 11%–16%). Two sets of duplicate laboratory-scale sequence batch bioreactors have been operated at organic loading rates (OLR) of 6.0 to 8.0 g total chemical oxygen demand (TCOD) kg−1 inoculum day−1 (d−1) during 210 days. The results demonstrated that the process is feasible at treatment cycle length (TCL) of 21 days; however, the quality of cow feces rather than the OLR had a direct influence on the specific methane yield (SMY). The SMY ranged between 124.5 ± 1.4 and 227.9 ± 4.8 normalized liter (NL) CH4 kg−1 volatile solids (VS) fed d−1. Substrate-to-inoculum mass ratio (SIR) was 0.63 ± 0.05, 0.90 ± 0.09, and 1.06 ± 0.07 at OLR of 6.0, 7.0, and 8.0 g TCOD kg−1 inoculum d−1, respectively. No volatile fatty acids (VFAs) accumulation has been observed which indicated that hydrolysis was the rate limiting step and VFAs have been consumed immediately. Bioreactors performance consistency in terms of the level of SMYs, VFAs concentrations at end of the TCL, pH stability and volatile solids reduction indicates a stable and reproducible process during the entire operation

Chemical Methods for Hydrolyzing Dairy Manure Fiber: A Concise Review

This paper reviews the chemical hydrolysis processes of dairy manure fiber to make its sugar accessible to microorganisms during anaerobic digestion and identifies obstacles and opportunities. Researchers, so far, investigated acid, alkali, sulfite, and advanced oxidation processes (such as hydrogen peroxide assisted by microwave/ultrasound irradiation, conventional boiling, and wet oxidation), or their combinations. Generally, dilute acid (3–10%) is less effective than concentrated acid (12.5–75%), which decrystallizes the cellulose. Excessive alkaline may produce difficult-to-degrade oxycellulose. Therefore, multi-step acid hydrolysis (without alkaline) is preferred. Such processes yielded 84% and 80% manure-to-glucose and -xylose conversion, respectively. Acid pretreatment increases lignin concentration in the treated manure and hinders subsequent enzymatic processes but is compatible with fungal cellulolytic enzymes which favor low pH. Manure high alkalinity affects dilute acid pretreatment and lowers glucose yield. Accordingly, the ratio of manure to the chemical agent and its initial concentration, reaction temperature and duration, and manure fineness need optimization because they affect the hydrolysis rate. Optimizing these factors or combining processes should balance removing hemicellulose and/or lignin and increasing cellulose concentrations while not hindering any subsequent process. The reviewed methods are neither economical nor integratable with the on-farm anaerobic digestion. Economic analysis and energy balance should be monolithic components of the research. More research is required to assess the effects of nitrogen content on these processes, optimize it, and determine if another pretreatment is necessary

Adapting anaerobic consortium to pure and complex lignocellulose substrates at low temperature: kinetics evaluation

Abstract Purposes The purpose of this research was to evaluate the kinetics of anaerobic microbial culture during adaptation to pure and complex lignocellulosic substrates at low temperature. Methods Six pairs of 1.0 L batch reactors maintained at 20 °C were fed pure (xylan and cellulose) and complex (cow manure and wheat straw) lignocellulosic substrate in three successive cycles of 35 days each. The biogas volume and composition, chemical oxygen demand, and volatile solids were monitored to evaluate the kinetics of the culture during the adaption. Results Anaerobic culture adapted to digest the pure and complex lignocellulosic substrates at 20 °C in relatively short period (105 days; 3 successive cycles of 35 days each) in batch reactor studies. The first-order model kinetics revealed that the average increase (day−1 cycle−1) in the reaction rate constant over the successive cycles was 0.0831 (xylan) > 0.0235 (cow manure) > 0.0207 (wheat straw) > 0.0123 (xylan:cellulose mixture) > 0.0041 (cellulose). The rates of the substrate degradation at 20 °C were: 0.085–0.093 day−1 (cellulose), 0.112–0.278 day−1 (xylan), 0.112–0.137 day−1 (xylan:cellulose mixture), 0.069–0.116 day−1 (cow manure), and 0.057–0.106 day−1 (wheat straw). Conclusions Anaerobic mixed culture can be adapted to pure and complex lignocellulosic substrates and convert them to methane at low temperature (20 °C) in relatively short time (105 days) using a sequential procedure. The culture adaptation to wheat straw proceeded at a slower rate than that for cow manure

Formic Acid Dehydrogenation Using Noble-Metal Nanoheterogeneous Catalysts: Towards Sustainable Hydrogen-Based Energy

The need for sustainable energy sources is now more urgent than ever, and hydrogen is significant in the future of energy. However, several obstacles remain in the way of widespread hydrogen use, most of which are related to transport and storage. Dilute formic acid (FA) is recognized asa a safe fuel for low-temperature fuel cells. This review examines FA as a potential hydrogen storage molecule that can be dehydrogenated to yield highly pure hydrogen (H2) and carbon dioxide (CO2) with very little carbon monoxide (CO) gas produced via nanoheterogeneous catalysts. It also present the use of Au and Pd as nanoheterogeneous catalysts for formic acid liquid phase decomposition, focusing on the influence of noble metals in monometallic, bimetallic, and trimetallic compositions on the catalytic dehydrogenation of FA under mild temperatures (20–50 °C). The review shows that FA production from CO2 without a base by direct catalytic carbon dioxide hydrogenation is far more sustainable than existing techniques. Finally, using FA as an energy carrier to selectively release hydrogen for fuel cell power generation appears to be a potential technique