Reviewing arsenic biomineralization: An upcoming strategy for mining wastewater treatment.

Human activities are the main cause of arsenic contamination in the environment and water resources, being the mining industry an important source of arsenic contamination because this element is released into the environment in solid, liquid, and gaseous wastes. Currently, several physical and chemical processes could be used for the removal of arsenic in water, but these alternatives depend on the concentration of arsenic. At low concentrations (nanograms or micrograms per liter) arsenic can be removed by membrane technologies.

MICP mediated by indigenous bacteria isolated from tailings for biocementation for reduction of wind erosion.

In this study, native ureolytic bacteria were isolated from copper tailings soils to perform microbial-induced carbonate precipitation (MICP) tests and evaluate their potential for biocement formation and their contribution to reduce the dispersion of particulate matter into the environment from tailings containing potentially toxic elements. It was possible to isolate a total of 46 bacteria; among them only three showed ureolytic activity: T130-1, sp. T130-13 and sp.

Formation of Recalcitrant Compounds during Anaerobic Digestion of Thermally Pre-Treated Sludge: A Critical Macromolecular and Structural Study.

Thermal hydrolysis, when used as pre-treatment, enhances the anaerobic digestion of sewage sludge; moreover, due to the high temperature normally applied, undesirable recalcitrant compounds via Maillard reactions may also be formed. However, although the appearance of these recalcitrant compounds is widely reported, more information on the formation, structure, and fate of these compounds is still needed. This study was focused on understanding the amount and whereabouts of such compounds during the anaerobic digestion process with thermal pre-treatment in soluble and total phase and advance in its structural identification by analyzing their infrared (IR) spectra.

On-Line Control of Feast/Famine Cycles to Improve PHB Accumulation during Cultivation of Mixed Microbial Cultures in Sequential Batch Reactors.

Production of polyhydroxyalkanoates (PHA) has generated great interest as building blocks for bioplastic production. Their production using mixed microbial cultures represents an interesting alternative, since it enables the use of organic wastes as a carbon source. Feast/famine strategy is a common way to promote selection of microorganisms with PHA accumulation capacity.

Micro-Oxygenation in Upflow Anaerobic Sludge Bed (UASB) Reactors Using a Silicon Membrane for Sulfide Oxidation.

Sulfide produced by sulphate-reducing bacteria in anaerobic reactors can seriously affect biogas quality. Microaeration has become a reliable way to remove sulfide, by promoting its oxidation. However, limited research is available regarding its application in upflow anaerobic sludge bed (UASB) reactors.

Making sense of parameter estimation and model simulation in bioprocesses.

Most articles that report fitted parameters for kinetic models do not include meaningful statistical information. This study demonstrates the importance of reporting a complete statistical analysis and shows a methodology to perform it, using functionalities implemented in computational tools. As an example, alginate production is studied in a batch stirred-tank fermenter and modeled using the kinetic model proposed by Klimek and Ollis (1980).

Application of microbe-induced carbonate precipitation for copper removal from copper-enriched waters: Challenges to future industrial application.

Copper contamination in watercourses is a recent issue in countries where mining operations are prevalent. In this study, the application of copper precipitation through microbe-induced carbonate precipitation (MICP) was analyzed using urea hydrolysis by bacteria to evaluate precipitated copper carbonates. This article demonstrates the application of a copper precipitation assay involving Sporosarcina pasteurii (in 0.

Maximizing energy recovery from wastewater via bioflocculation-enhanced primary treatment: a pilot scale study.

Anaerobic digestion of municipal sewage sludge is widely used for harvesting energy from wastewater organic content. The more organic carbon we can redirect into the primary sludge, the less energy is needed for aeration in secondary treatment and the more methane is produced in anaerobic digesters. Bioflocculation has been proposed as a promising separation technology to maximize carbon capture in primary sludge.

Effect of Operational Conditions on the Behaviour and Associated Costs of Mixed Microbial Cultures for PHA Production.

Massive production and disposal of petrochemical derived plastics represent relevant environmental problems. Polyhydroxyalkanoates (PHA) are a renewable alternative that can even be produced from wastes. The production of PHA from acetate using mixed microbial cultures was studied.

The accumulation of volatile fatty acids and phenols through a pH-controlled fermentation of olive mill solid waste.

This work aims to compare the use of olive mill solid waste as substrate in pH-controlled fermentation at acid (pH = 5), neutral (uncontrolled, pH ≈ 7) and alkaline (pH = 9) operating pH levels. The results obtained in this study indicate that operating pH strongly affected the anaerobic microorganisms and, hence, different target compounds could be obtained by adjusting the operating pH. Fermentation at neutral pH resulted in the conversion of 93.

A need for a standardization in anaerobic digestion experiments? Let's get some insight from meta-analysis and multivariate analysis.

An important variability in the experimental results in anaerobic digestion lab test has been reported. This study presents a meta-analysis coupled with multivariate analysis aiming to assess the impact of this experimental variability in batch and continuous operation at mesophilic and thermophilic anaerobic digestion of waste activated sludge. An analysis of variance showed that there was no significant difference between mesophilic and thermophilic conditions in both continuous and batch conditions.

A membrane aerated biofilm reactor for sulfide control from anaerobically treated wastewater.

A upflow anaerobic sludge blanket reactor was operated combined to a membrane aerated biofilm reactor for sulfate removal and for elemental sulfur reclamation. A commercial silicon tube was used as an oxygen delivery diffuser. The process achieved high rates of sulfide removal from the liquid phase (90%).

Use of activated sludge biomass as an agent for advanced primary separation.

Conventional primary settling is a physical process of solid-liquid separation, normally presenting low removal efficiencies. Improvement of this separation process would result in energetic advantages: lower aeration requirements and higher biogas production form primary and secondary sludges. Secondary sludge has been proposed as a potential agent promoting an increase in primary separation efficiency.

Screening of biomethane production potential from dominant microalgae.

The use of microalgae for biomethane production has been considerably increasing during the recent years. In this study, four dominant species belonging to the genera Scenedesmus, Chlorella, Dunaliella and Nostoc were selected. The influence of different genera with several morphological, structural and physicochemical characteristics on methane production was assessed in biochemical methane potential (BMP) tests.

Batch anaerobic co-digestion of waste activated sludge and microalgae (Chlorella sorokiniana) at mesophilic temperature.

The microalgae Chlorella sorokiniana are used as co-substrate for waste activated sludge (WAS) anaerobic digestion. The specific objective of this research was to evaluate the feasibility of improving methane production from anaerobic digestion of WAS in co-digestion with this microalga, based on an optimized mixture percentage. Thus, the anaerobic co-digestion of both substrates aims to overcome the drawbacks of the anaerobic digestion of single WAS, simultaneously improving its management.

Use of cellulolytic marine bacteria for enzymatic pretreatment in microalgal biogas production.

In this study, we designed and evaluated a microalgal pretreatment method using cellulolytic bacteria that naturally degrades microalgae in their native habitat. Bacterial strains were isolated from each of two mollusk species in a medium containing 1% carboxymethyl cellulose agar. We selected nine bacterial strains that had endoglucanase activity: five strains from Mytilus chilensis, a Chilean mussel, and four strains from Mesodesma donacium, a clam found in the Southern Pacific.

Enzymatic biodiesel production kinetics using co-solvent and an anhydrous medium: a strategy to improve lipase performance in a semi-continuous reactor.

Enzymatic biodiesel production kinetics under previously optimized conditions were investigated. Waste frying oil (WFO) was used as the raw material, Novozym 435 as catalyst, methanol as acyl acceptor and tert-butanol as co-solvent. To investigate pure transesterification kinetics improving product properties, 3Å molecular sieves were incorporated into the reaction to provide an anhydrous medium avoiding the side reactions of hydrolysis and esterification.

Behavior of the anaerobic treatment of tannery wastewater at different initial pH values and sulfate concentrations.

The influence of initial pH and sulfate concentration on the anaerobic digestion of tannery wastewater was studied using the specific methanogenic activity (SMA) test. The SMA tests were performed with a chemical oxygen demand (COD) concentration of 6.5 g/L and SO(-2)4 concentrations of 1.

Potentials of anaerobic membrane bioreactors to overcome treatment limitations induced by industrial wastewaters.

This review presents a comprehensive summary on applications of anaerobic membrane bioreactor (AnMBR) technology for industrial wastewaters in view of different aspects including treatability and filterability. AnMBRs present an attractive option for the treatment of industrial wastewaters at extreme conditions, such as high salinity, high temperature, high suspended solids concentrations, and toxicity that hamper granulation and retention of biomass or reduce the biological activity. So far, most of the research has been conducted at laboratory scale; however, also a number of full-scale AnMBR systems is currently being operated worldwide.

Effects of the acidogenic biomass on the performance of an anaerobic membrane bioreactor for wastewater treatment.

Continuous flow experiments were performed to study the effects of acidogenic biomass development, induced by feeding with non-acidified substrate, on the operation and performance of an anaerobic membrane bioreactor (AnMBR). The AnMBR was operated at cross-flow velocities up to 1.5m/s and fed with a gelatine-starch-ethanol mixture.