Study of the acclimation stage and of the effect of the biodegradability on the performance of a microbial fuel cell

In this work, it has been studied the production of electricity and the oxidation of the pollutants contained in a synthetic wastewater fed with glucose and peptone of soybean as carbon sources, using a mediator-less microbial fuel cell (MFC). Special attention has been paid to the acclimation stage, in which it was found that with high hydraulic and solid retention times it is possible to obtain a very efficient process with a 90% COD removal and practically total conversion of COD into electricity (considering the typical stoichiometric yield of heterotrophic biomass). The influence of concentration sludge was studied working with three different amounts of suspended solids, from 120 to 14000 mg. The maximum power density increased exponentially with the concentration sludge from 2.1 mW m⁻² to 11 mW m⁻² at the highest concentration sludge. More over, the percentage of the influent COD used to produce electricity was higher than 100% when the highest sludge concentration was used. This was explained taking into account the endogenous metabolism of micro-organisms presented in the system.     

Application of alkaline treatment for sludge decrement and humic acid recovery

A new method was introduced to reduce waste activated sludge and extract humic acid for liquid fertilizer. Sludge was disintegrated with NaOH (0.4 g/g dry solid, 8 h) and then centrifuged to obtain the supernatant. The residual sludge was then dewatered, while the supernatant was used to extract humic acid with an ultrafiltration membrane. The results showed that the alkaline treatment dissolved more than half of the sludge organic matter, which was composed of 24% humic acid by mass. After the supernatant was concentrated 20 times using a membrane with a molecular weight cutoff of 1000, the retentate contained 94.5% of the dissolved organics and could be used to produce humic acid fertilizer. Additionally, only 26% of the NaOH was consumed and the residual NaOH in the permeate flux could be reused. Due to the removal of water and organics, the dewatered sludge could be reduced by 60% when compared to samples that did not receive the alkaline treatment.     

Energy use and recovery strategies within wastewater treatment and sludge handling at pulp and paper mills

This paper presents an inclusive approach with focus on energy use and recovery in wastewater management, including wastewater treatment (WWT) and sludge handling. Process data from three Swedish mills and a mathematical model were used to evaluate seven sludge handling strategies. The results indicate that excess energy use in WWT processes counters the potential energy recovery in the sludge handling systems. Energy use in WWT processes is recommended to aim for sufficient effluent treatment, not for sludge reduction. Increased secondary sludge production is favourable from an energy point of view provided it is used as a substrate for heat, biogas or electricity production.     

Anaerobic degradation pathway and kinetics of domestic wastewater at low temperatures

The effect of temperatures below 20 °C (20, 15 and 10 °C) on the anaerobic degradation pathway and kinetics of domestic wastewater fractionated at different sizes was studied in a fluidized-bed batch reactor. The overall degradation pathway was characterized by a soluble fraction degrading according to zero-order kinetics and a colloidal fraction (between 0.45 and 4.5 μm) that first disintegrates into a particulate fraction smaller than 0.45 μm before finally degrading. The colloidal degradation processes follow a first-order kinetic. In contrast, suspended solids (bigger than 4.5 μm) degrade to soluble and colloidal fractions according to first-order kinetics. The colloidal fraction originating from suspended solids further degrades into soluble fraction. These soluble fractions have the same degradation kinetics as the original soluble fraction. The suspended solids degradation was highly affected by temperature, whereas the soluble fraction slightly affected and the colloidal fraction was not affected at all. On the other hand, the colloidal non-degradable fraction increased significantly with the decrease in temperature while the suspended solids slowly increased. The soluble non-degradable fraction was little affected by temperatures changes.     

Sustainable intensive livestock production demands manure and exhaust air treatment technologies

Intensive livestock production is connected with a number of environmental effects, including discharges to soils and surface waters and emissions to the atmosphere. In areas with a high livestock density the low availability of nearby arable land, together with the preferred use of chemical fertilizer by arable farmers, results in high off-farm disposal costs for manure. Furthermore, ammonia abatement technologies, such as treatment of exhaust air, are important as ammonia emissions may account up to a quarter of the total nitrogen flux.     

Improved infiltration of stem cells on electrospun nanofibers

Nanofibrous scaffolds have been recently used in the field of tissue engineering because of their nano-size structure which promotes cell attachment, function, proliferation and infiltration. In this study, nanofibrous polyethersulfone (PES) scaffolds was prepared via electrospinning. The scaffolds were surface modified by plasma treatment and collagen grafting. The surface changes then investigated by contact angle measurements and FTIR-ATR. The results proved grafting of the collagen on nanofibers surface and increased hydrophilicity after plasma treatment and collagen grafting. The cell interaction study was done using stem cells because of their ability to differentiate to different kinds of cell lines. The cells had normal morphology on nanofibers and showed very high infiltration through collagen grafted PES nanofibers. This infiltration capability is very useful and needed to make 3D scaffolds in tissue engineering.     

Preparation of inulin and phenols-rich dietary fibre powder from burdock root

The simultaneous ultrasonic/microwave assisted extraction (UMAE) of inulin and production of phenols-rich dietary fibre powder from burdock root was studied. It was found that UMAE required a much shorter extraction time than conventional stirring extraction. And the recovery of inulin increased with the increase of microwave power as well as solvent to solid ratio. A comparison of scanning electron microscopy images of raw and simultaneous ultrasonic/microwave treated burdock root indicated microfractures and disruption of cell walls in burdock root flakes. The dietary fibre powder prepared from the residue of burdock root after inulin extraction was rich in phenols (302.62 mg GAE/100 g powder). The results showed that drying temperature in the selected range did not significantly affect the hydration properties. The relatively high water retention capacity, swelling capacity and oil-holding capacity of the dietary fibre powder indicated its broad use as a modifier of properties of formulated products.     

New concept of contaminant removal from swine wastewater by a biological treatment process

Pollution from concentrated animal feeding operations (CAFOs) are the most serious pollution source in China now, and swine wastewater contains high concentrations of nutrients such as chemical oxygen demand (COD), biochemical oxygen demand 5 (BOD5), ammonium, and emergent contaminants related to public health. Biological processes are the most popular treatment methods for COD and ammonium removal. Considering the low operation cost, easy maintenance and high removal rate of contaminants in recent years, nitrogen removal via nitrite and real-time control processes using oxidation-reduction potential (ORP) and/or pH as parameters to control the aerobic and anaerobic cycles of a system has received much attention for animal wastewater treatment. During the biological treatment process, the emergent contaminants such as estrogen, antibiotics, and disinfec-tion reagents have been the focus of research recently, and degradation bacteria and resistance bacteria have also been extracted from activated sludge. The microbial analysis technique is also advancement in the field of biodegrada-tion bacteria and resistance bacteria. All of these advance-ments in research serve to improve wastewater treatment and decrease environmental hazards, especially for using manure as a fertilizer source for crop production.     

pI-based fractionation of serum proteomes versus anion exchange after enhancement of low-abundance proteins by means of peptide libraries

The pre-treatment of biological extracts with the aim of detecting very low-abundance proteins generates complexity requiring a proper fractionation. Therefore the success of identifying all newly detectable species depends on the selected fractionation methods.In this context and starting from a human serum, where the dynamic concentration range was reduced by means of a preliminary treatment with a combinatorial hexapeptide ligand library, we fractionated the sample using a novel method based on the differences in isoelectric points of proteins by means of Solid-State Buffers (SSB) associated with cation exchangers. The number of fractions was limited to four and was compared to a classical anion exchange method generating the same number of fractions.What was observed is that when using SSB technology the protein redundancy between fractions was significantly reduced compared to ion exchange fractionation allowing thus a better detection of novel species. The analysis of trypsinized protein fractions by nanoLC-MS/MS confirmed that the SSB technology used is more discriminant than anion exchange chromatography fractionation.A sample fractionation by SSB after the reduction of dynamic concentration range can be accomplished without either adjustment of pH and ionic strength or protein concentration and cleanup. Both advantages over either classical chromatography or isoelectric fractionations allow approaching the discovery of markers of interest under easier conditions applicable in a variety of fields of investigation.