Bioelectrochemical extraction of ammonium from low-strength wastewater with concomitant generation of high-purity hydrogen.

Bioelectrochemical systems (BES) are emerging environmental biotechnology for recovering ammonia from waste streams. It has been tested extensively for treating ammonium-rich wastewater. This study examined the suitability of BES to facilitate carbon removal and ammonium extraction from a low ammonium liquor (3.

Sustained and enhanced anaerobic removal of COD and nitrogen in a zeolite amended glycogen accumulating organism dominated biofilm process.

Activated sludge, the most widely used biological wastewater treatment process is known to be expensive to operate, largely due to energy expense for oxygen transfer into the bulk wastewater solution. The alternative of using passive aeration facilitates oxygen supply directly from the air resulting in aeration energy savings. The current study demonstrated sustained and improved removal of chemical oxygen demand (COD) and nitrogen in a zeolite modified glycogen accumulating organisms (GAOs) dominated biofilm reactor, which achieved anaerobic removal of COD and ammonium by the activity of GAOs and zeolite, respectively.

Novel microbial-electrochemical filter with a computer-feedback pH control strategy for upgrading biogas into biomethane.

A novel microbial-electrochemical filter was designed and operated based on a combined microbial electrolysis cell and bio-trickling filter principles with the aim to maximize gas-liquid mass-transfer efficiency and minimize costs associated with bubbling biogas through liquid-filled reactor. CO/biogas feed to the MEF was done via a computer-feedback pH control strategy, linking CO feed directly to the OH production. As a result current efficiency was constant at around 100% throughout the period of experiments.

Energy efficient COD and N-removal from high-strength wastewater by a passively aerated GAO dominated biofilm.

Conventional aerobic treatment of high-strength wastewater is not economical due to excessively high energy requirement for compressed air supply. The use of passive aeration avoids the use of compressed air and enables energy efficient oxygen supply directly from the air. This study evaluates a passively aerated simultaneous nitrification and denitrification performing biofilm to treat concentrated wastewater.

Proof of concept of wastewater treatment via passive aeration SND using a novel zeolite amended biofilm reactor.

The current paper describes a novel passive aeration simultaneous nitrification and denitrification (PASND) zeolite amended biofilm reactor that removes organic carbon and nitrogen from wastewater with low-energy consumption. Next to the ammonium oxidizing bacteria (AOB), this reactor contained naturally enriched glycogen accumulating organisms (GAOs) and zeolite powder to initially adsorb BOD (acetate) and ammonium (NH -N) from synthetic wastewater under anaerobic conditions. Draining of the treated wastewater exposed the biofilm directly to air enabling low-energy oxygen supply by passive aeration.

Direct oxygen uptake from air by novel glycogen accumulating organism dominated biofilm minimizes excess sludge production.

The cost associated with treatment and disposal of excess sludge produced is one of the greatest operational expenses in wastewater treatment plants. In this study, we quantify and explain greatly reduced excess sludge production in the novel glycogen accumulating organism (GAO) dominated drained biofilm system previously shown to be capable of extremely energy efficient removal of organic carbon (biological oxygen demand or BOD) from wastewater. The average excess sludge production rate was 0.

Ethanol and lactic acid production from sugar and starch wastes by anaerobic acidification.

Anaerobic conversion of carbohydrates can generate various end-products. Besides physical parameters such as pH and temperature, the types of carbohydrate being fermented influences the fermentation pattern. Under uncontrolled pH, microbial mixed cultures from activated sludge and anaerobic digester sludge anaerobically produced ethanol from glucose while producing lactic acid from starch conversion.

Anaerobic acidification of sugar-containing wastewater for biotechnological production of organic acids and ethanol.

Anaerobic acidification of sugars can produce some useful end-products such as alcohol, volatile fatty acids (e.g. acetate, propionate, and butyrate) and lactic acid.

Concurrent Lactic and Volatile Fatty Acid Analysis of Microbial Fermentation Samples by Gas Chromatography with Heat Pre-treatment.

Organic acid analysis of fermentation samples can be readily achieved by gas chromatography (GC), which detects volatile organic acids. However, lactic acid, a key fermentation acid is non-volatile and can hence not be quantified by regular GC analysis. However the addition of periodic acid to organic acid samples has been shown to enable lactic acid analysis by GC, as periodic acid oxidizes lactic acid to the volatile acetaldehyde.

Bioelectrochemical enhancement of anaerobic digestion: Comparing single- and two-chamber reactor configurations at thermophilic conditions.

Bioelectrochemical system (BES) can act as an auxiliary technology for improving organic waste treatment and biogas production in anaerobic digestion (AD). For the first time this study directly compared the performance of a single- and a cation-exchange membrane-equipped two-chamber BES-AD systems at thermophilic conditions. The results indicated that an active glucose-fed thermophilic anaerobic sludge could readily (<3days) increase biogas production in both reactor configurations by inserting a carbon electrode poised at -0.

Rapid adaptation of activated sludge bacteria into a glycogen accumulating biofilm enabling anaerobic BOD uptake.

Glycogen accumulating organisms (GAO) are known to allow anaerobic uptake of biological oxygen demand (BOD) in activated sludge wastewater treatment systems. In this study, we report a rapid transition of suspended activated sludge biomass to a GAO dominated biofilm by selective enrichment using sequences of anaerobic loading followed by aerobic exposure of the biofilm to air. The study showed that within eight weeks, a fully operational, GAO dominated biofilm had developed, enabling complete anaerobic BOD uptake at a rate of 256mg/L/h.

New method for characterizing electron mediators in microbial systems using a thin-layer twin-working electrode cell.

Microbial biofilms are significant ecosystems where the existence of redox gradients drive electron transfer often via soluble electron mediators. This study describes the use of two interfacing working electrodes (WEs) to simulate redox gradients within close proximity (250µm) for the detection and quantification of electron mediators. By using a common counter and reference electrode, the potentials of the two WEs were independently controlled to maintain a suitable "voltage window", which enabled simultaneous oxidation and reduction of electron mediators as evidenced by the concurrent anodic and cathodic currents, respectively.

Automatic online buffer capacity (alkalinity) measurement of wastewater using an electrochemical cell.

The use of an automatic online electrochemical cell (EC) for measuring the buffer capacity of wastewater is presented. pH titration curves of different solutions (NaHCO3, Na2HPO4, real municipal wastewater, and anaerobic digester liquid) were obtained by conventional chemical titration and compared to the online EC measurements. The results show that the pH titration curves from the EC were comparable to that of the conventional chemical titration.

Simultaneous phosphorus uptake and denitrification by EBPR-r biofilm under aerobic conditions: effect of dissolved oxygen.

A biofilm process, termed enhanced biological phosphorus removal and recovery (EBPR-r), was recently developed as a post-denitrification approach to facilitate phosphorus (P) recovery from wastewater. Although simultaneous P uptake and denitrification was achieved despite substantial intrusion of dissolved oxygen (DO >6 mg/L), to what extent DO affects the process was unclear. Hence, in this study a series of batch experiments was conducted to assess the activity of the biofilm under various DO concentrations.

Novel process of bio-chemical ammonia removal from air streams using a water reflux system and zeolite as filter media.

A novel biofilter that removes ammonia from air streams and converts it to nitrogen gas has been developed and operated continuously for 300 days. The ammonia from the incoming up-flow air stream is first absorbed into water and the carrier material, zeolite. A continuous gravity reflux of condensed water from the exit of the biofilter provides moisture for nitrifying bacteria to develop and convert dissolved ammonia (ammonium) to nitrite/nitrate.

Organic carbon removal from wastewater by a PHA storing biofilm using direct atmospheric air contact as oxygen supply.

The principal reason for the high energy costs for biological wastewater treatment is the poor transfer efficiency of oxygen to the bulk water phase. The current paper describes a biofilm reactor in which oxygen transfer to the bulk solution is avoided by alternating anaerobic submersed (2h) and drained (1h) operation of the biofilm. During the submersed phase the biofilm enriched for glycogen accumulating organism (GAO) stored the organic carbon (acetate) as poly-hydroxy-alkanoate (PHA).

Microbial fuel cell biosensor for rapid assessment of assimilable organic carbon under marine conditions.

The development of an assimilable organic carbon (AOC) detecting marine microbial fuel cell (MFC) biosensor inoculated with microorganisms from marine sediment was successful within 36 days. This established marine MFC was tested as an AOC biosensor and reproducible microbiologically produced electrical signals in response to defined acetate concentration were achieved. The dependency of the biosensor sensitivity on the potential of the electron-accepting electrode (anode) was investigated.

In-line deoxygenation for organic carbon detections in seawater using a marine microbial fuel cell-biosensor.

Assimilable organic carbon (AOC) is a key predictor for membrane biofouling in seawater desalination reverse osmosis (SWRO). Microbial fuel cells have been considered as biosensors for the detection of biodegradable organics. However, the presence of dissolved oxygen (DO) is known to completely suppress the signal production (i.

Hexacyanoferrate-adapted biofilm enables the development of a microbial fuel cell biosensor to detect trace levels of assimilable organic carbon (AOC) in oxygenated seawater.

A marine microbial fuel cell (MFC) type biosensor was developed for the detection of assimilable organic carbon (AOC) in ocean water for the purpose of online water quality monitoring for seawater desalination plants prone to biofouling of reverse osmosis (RO) membranes. The anodophilic biofilm that developed on the graphite tissue anode could detect acetate as the model AOC to concentrations as low as 5 µM (120 µg/L of AOC), which is sufficiently sensitive as an online biofouling risk sensor. Although the sensor was operated at a higher (+200 ± 10 mV) than the usual (-300 mV) anodic potential, the presence of oxygen completely suppressed the electrical signal.

Selective enrichment and production of highly urease active bacteria by non-sterile (open) chemostat culture.

In general, bioprocesses can be subdivided into naturally occurring processes, not requiring sterility (e.g., beer brewing, wine making, lactic acid fermentation, or biogas digestion) and other processes (e.

Enhancement of waste activated sludge anaerobic digestion by a novel chemical free acid/alkaline pretreatment using electrolysis.

Anaerobic digestion of waste activated sludge (WAS) is relatively poor due to hydrolysis limitations. Acid and alkaline pretreatments are effective in enhancing hydrolysis leading to higher methane yields. However, chemical costs often prohibit full-scale application.

Ammonia recycling enables sustainable operation of bioelectrochemical systems.

Ammonium (NH4(+)) migration across a cation exchange membrane is commonly observed during the operation of bioelectrochemical systems (BES). This often leads to anolyte acidification (pH <5.5) and complete inactivation of biofilm electroactivity.

Simplifying cellulase production by using environmental selection pressures and recycling substrate.

The production of crude cellulase in solid-state fermentation was simplified by using environmental selection pressures as an alternative to specialized strains and by re-using cellulose-to-ethanol fermentation substrate for cellulase production. The performance of wild strains of Trichoderma viride isolated from wheat and bark were found not to differ significantly from a 'cellulase-enhanced' strain of Trichoderma reesei. The filter paper activity of a strain of Aspergillus niger isolated in the laboratory was more than two times higher than the specialized T.

Overcoming sodium toxicity by utilizing grass leaves as co-substrate during the start-up of batch thermophilic anaerobic digestion.

Sodium toxicity is a common problem causing inhibition of anaerobic digestion, and digesters treating highly concentrated wastes, such as food and municipal solid waste, and concentrated animal manure, are likely to suffer from partial or complete inhibition of methane-producing consortia, including methanogens. When grass clippings were added at the onset of anaerobic digestion of acetate containing a sodium concentration of 7.8 gNa(+)/L, a total methane production about 8L/L was obtained, whereas no methane was produced in the absence of grass leaves.