Search results for "reactors"

Oxygen transfer performance of unbaffled stirred vessels in view of their use as biochemical reactors for animal cell growth

2012

Cultivation of microorganisms, plants or animal cells requires liquid agitation in order to ensure oxygen and nutrient transfer and to maintain cell suspension. However, In such suspensions both mechanical agitation and sparging aeration can cause cell death. Many studies on animal cell damage due to mechanical agitation and sparging aeration have shown that mechanical damage of freely suspended animal cells is in most cases associated with bursting bubbles at the air–liquid interface (Barrett et al., 2010, Nienow et al., 1996). Gas bubbles are usually generated by direct air sparging to propagate oxygen in a culture suspension. Mechanical agitation may also introduce gas bubbles to the cul…

Modelling wet-air oxidation of phenol in a trickle-bed reactor using active carbon as a catalyst

2016

Calcium effect on enhanced biological phosphorus removal.

2006

The role of calcium (Ca) in enhanced biological phosphorus removal and its possible implications on the metabolic pathway have been studied. The experience has been carried out in an SBR under anaerobic–aerobic conditions for biological phosphorus removal during 8 months. The variations of influent Ca concentration showed a clear influence on the EBPR process, detecting significant changes in YPO4. These YPO4 variations were not due to influent P/COD ratio, pH, denitrification and calcium phosphate formation. The YPO4 has been found to be highly dependent on the Ca concentration, increasing as Ca concentration decreases. The results suggest that high Ca concentrations produce “inert” granul…

Salinity affects nitrate removal and microbial composition of denitrifying woodchip bioreactors treating recirculating aquaculture system effluents

2019

Abstract This study investigated the effect of salinity on microbial composition and denitrification capacity of woodchip bioreactors treating recirculating aquaculture system (RAS) effluents. Twelve laboratory-scale woodchip bioreactors were run in triplicates at 0, 15, 25, and 35 ppt salinities, and water chemistry was monitored every third day during the first 39 days of operation. Microbial communities of the woodchips bioreactors were analyzed at the start, after one week, and at the end of the trial. Woodchip bioreactors removed nitrate at all salinities tested. The highest NO3-N removal rate of 22.0 ± 6.9 g NO3-N/m3/d was obtained at 0 ppt, while 15.3 ± 4.9, 12.5 ± 5.4 and 11.8 ± 4.0…

Microbial communities in full-scale woodchip bioreactors treating aquaculture effluents.

2021

Woodchip bioreactors are being successfully applied to remove nitrate from commercial land-based recirculating aquaculture system (RAS) effluents. In order to understand and optimize the overall function of these bioreactors, knowledge on the microbial communities, especially on the microbes with potential for production or mitigation of harmful substances (e.g. hydrogen sulfide; H2S) is needed. In this study, we quantified and characterized bacterial and fungal communities, including potential H2S producers and consumers, using qPCR and high throughput sequencing of 16S rRNA gene. We took water samples from bioreactors and their inlet and outlet, and sampled biofilms growing on woodchips a…

Population Dynamic of Algae and Bacteria in an Oxidation Channel

2003

A study on algae and bacteria population changes, as a function of time, was carried out in a pilot scale oxidation channel bioreactor using a carrousel system. Total Coliforms, Pseudomonas aeruginosa, and Streptococcus faecalis, the most common bacteria found in sewage, Scenedesmus obliquus and Chlorella vulgaris were the microalgae considered in this work. Physicochemical parameters such as COD, BOD, Chlorophyll a, nitrogen, and phosphorous compounds were studied and determined during the experiments. It was demonstrated that the level of wastewater contamination could be predicted based on the bacterial and algae composition. The relationships between the algae and bacteria population, a…

Biological nutrient removal in membrane bioreactors: denitrification and phosphorus removal kinetics.

2007

The impact of including membranes for solid liquid separation on the kinetics of nitrogen and phosphorus removal was investigated. To achieve this, a membrane bioreactor (MBR) biological nutrient removal (BNR) activated sludge system was operated. From batch tests on mixed liquor drawn from the MBR BNR system, denitrification and phosphorus removal rates were delineated. Additionally the influence of the high total suspended solids concentrations present in the MBR BNR system and of the limitation of substrate concentrations on the kinetics was investigated. Moreover the ability of activated sludge in this kind of system to denitrify under anoxic conditions with simultaneous phosphate uptak…

Co-treatment of landfill leachate in laboratory-scale sequencing batch reactors: analysis of system performance and biomass activity by means of resp…

2014

Aged or mature leachate, produced by old landfills, can be very refractory; for this reason mature leachate is difficult to treat alone, but it can be co-treated with sewage or domestic wastewater. The aim of the study was to investigate the feasibility of leachate co-treatment with synthetic wastewater, in terms of process performance and biomass activity, by means of respirometric techniques. Two sequencing batch reactors (SBRs), named SBR1 and SBR2, were fed with synthetic wastewater and two different percentages of landfill leachate (respectively 10% and 50% v v−1 in SBR1 and SBR2). The results showed good chemical oxygen demand (COD) removal efficiency for both reactors, with average C…

Electrochemical incineration of oxalic acid in a micro-gap flow cell

2009

Removal of bis (2-ethylhexyl) phthalate from reject water in a nitrogen-removing sequencing batch reactor.

2003

Reject water from sewage sludge processing may contain high concentrations of nutrients and organic pollutants and cause internal pollution load at a sewage treatment plant (STP) if circulated to the headworks of an STP. In the present study removal of nitrogen and bis (2-ethylhexyl) phthalate (DEHP) from reject water was studied in two sequencing batch reactors (SBRs) with different aerobic/anoxic periods during a 6-h total cycle period. Ammonia-nitrogen (NH(4)-N) was almost totally removed in both reactors, apparently by nitrification throughout the run, while denitrification declined with decreasing SCOD in the influent resulting in an increase in the effluent nitrate-nitrogen (NO(3)-N) …