Michael John Dempsey

• PhD
• Managing Director at Advanced Bioprocess Development Ltd.

Prokaryotes that can oxidize ammonia and/or nitrite are known as nitrifiers and are common in terrestrial, freshwater and marine environments. Where the temperature is commonly in the range 0–20 °C, psychrophilic strains or species can be isolated or identified using molecular techniques. It is therefore no surprise to also find psychrophilic nitri...

Citrate functionalised gold nanoparticles (AuNPs) have been shown to be effective heavy metal sensors, as their optical spectra quantitatively shifts upon metal-citrate interaction. The speciation and molecular orientation of citrate molecules absorbed on the surfaces of bulk materials is found to be dependent on the substrate material used. It is...

Citrate functionalised gold nanoparticles (AuNPs) display strong surface enhanced Raman scattering, which can be used for surface enhanced Raman spectroscopy (SERS). The specific and strong interaction between the heavy metal ions and surface-bound citrate molecules lead to a sensing application for the detection of Pb2+ ions. Herein we report a ci...

Excessive ammonia in raw water increases the consumption of chlorine for disinfection during production of potable water, through oxidation to produce chloramines. Excessive ammonia in used water results in pollution of the aquatic environment, where it is particularly toxic to fish. Furthermore, nitrifying prokaryotes in the receiving water will c...

The fluidized bed biofilm reactor (FBBR) has been used for anaerobic digestion, carbon oxidation, nitrification, and denitrification of industrial and municipal wastewaters. Most recently, it has been used at full-scale for municipal tertiary denitrification. In fact, the FBBR has the highest biomass density and smallest footprint of any tertiary t...

By determining the rate of microbial activity under optimum conditions, actual process performance can be compared and improved if necessary. We are investigating expanded bed bioreactor (EBBR) technology for a variety of processes and have developed a method for measuring the activity of intact bioparticles (1 mm support with biofilm). Furthermore...

We investigated the influence of biofilm thickness on the rate of ammonia oxidation, using nitrifying biofilm grown on glassy coke. In this study, ammonia oxidaWe investigated the influence of biofilm thickness on the rate of ammonia oxidation, using nitrifying biofilm grown on glassy coke. In this study, ammonia oxidation was taken as an indicatio...

We investigated the influence of biofilm thickness on the rate of ammonia oxidation, using nitrifying biofilm grown on glassy coke. In this study, ammonia oxidaWe investigated the influence of biofilm thickness on the rate of ammonia oxidation, using nitrifying biofilm grown on glassy coke. In this study, ammonia oxidation was taken as an indicatio...

On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the Environment: Implications of Use under Pandemic Conditions to assess the potential human health impact and environmental hazards associated with use of Tamiflu during an influenza pandemic. Based on the identification and risk-ranking of knowledge gaps,...

Purified alkali stable xylanase from Aspergillus fischeri was immobilized on polystyrene beads using diazotization method. An expanded bed bioreactor was developed with these immobilized beads to biobleach the paper pulp in continuous mode. Response surface methodology was applied to optimize the biobleaching conditions. Temperature (degrees C), fl...

The expanded bed biofilm reactor (EBBR) was developed by Advanced Bioprocess Development Ltd. (ABD) to provide a compact tertiary nitrification process. In terms of performance, the EBBR can meet an NH3-N discharge of less than 1 mg/L at high volumetric loading rates (1.0 kg NH3-N/m3 expanded bed/day). This high rate results from a predominance of...

Method and apparatus (8) in which a biomass is carried on a substrate which is fluidised. The fluidised substrate has below it a lazer of distributor particles through which the fluidising medium passes prior to contact with the fluidised substrate and biomass associated therewith. The effect of the distributor layer is that the particles damp out...

Using a growth medium based on cane blackstrap molasses, we compared ethanol production by two strains of Saccharomyces cerevisiae that were immobilized in polyurethane foam cubes in a fluidised-bed fermenter. One strain (NCYC 1119) was adhesive and extremely flocculent, whilst the other strain was not adhesive and only weakly flocculent. The stron...

Developed for tertiary nitrification, this biofilter also removed carbonaceous BOD (cBOD) and (SS). Because the biofilter is expanded, it cannot clog, and therefore does not require backflushing; yet, it removed a significant proportion of the influent SS. This unanticipated capability was due to the activities of heterotrophic bacteria, protozoa,...

Method and apparatus (8) in which a biomass is carried on a substrate which is fluidised. The fluidised substrate has below it a lazer of distributor particles through which the fluidising medium passes prior to contact with the fluidised substrate and biomass associated therewith. The effect of the distributor layer is that the particles damp out...

The performance of a particulate-biofilm, expanded-bed process for nitrification of activated sludge final effluent (ASFE) is reported for a plant receiving mixed industrial and domestic wastewater. The support material for the particulate-biofilms was glassy coke, to which the nitrifying bacteria attached and formed a highly active biofilm. An ave...

Increased protection of the aquatic environment requires improved wastewater treatment. However, this increases costs, through increased energy consumption and associated CO2 emissions. To meet the growing demand for sustainable wastewater treatment, we have developed a simple, energy-efficient technology. Although originally for nitrification, it...

The present invention concerns the field of nitrification of fluids, and particularly relates to the treatment of aqueous fluids to oxidize ammonia and nitrites to produce nitrates. One aspect of the present invention seeks to provide an alternative nitrification process which is readily capable of commercial implementation, and in which the nitrif...

The present invention concerns the field of nitrification of fluids, and particularly relates to the treatment of aqueous fluids to oxidize ammonia and nitrites to produce nitrates. One aspect of the present invention seeks to provide an alternative nitrification process which is readily capable of commercial implementation, and in which the nitrif...

Method and apparatus (8) in which a biomass is carried on a substrate which is fluidised. The fluidised substrate has below it a lazer of distributor particles through which the fluidising medium passes prior to contact with the fluidised substrate and biomass associated therewith. The effect of the distributor layer is that the particles damp out...

Mounted on the Internet with the permission of The Biochemical Society (2001). A new method for continuous biopanning has been developed. We have combined the power of affinity chromatography with the fecundity of bacteria in a unique process that mimics clonal selection. Mixed populations of bacteria were applied to a fermenter containing the immo...

In this paper, computational intelligence has been considered as a tool (software sensor) for state-estimation and prediction of biomass concentration in a simulated fermentation process. Two different paradigms of an artificial neural networks have been introduced as possible computational engines. Inclusion of process dynamics is inherent within...

The exploitation of biofilms in industrial processes such as wastewater treatment and metabolite production is described. In this way it is intended to highlight the positive aspects of biofilms, and provide a contrast with the negative associations which these microbial aggregations normally have. In particular, the exploitation of adhesive microb...

Immobilization of biomass within a fermenter produces a large increase in cell concentration, which results in a substantial increase in volumetric productivity (rp, mass of product per unit volume of fermenter per unit time). For primary metabolites, immobilization allows continuous culture operation at dilution rates in excess of μmax; whilst for...

Classical experimental design requires that only one variable is changed at a time — otherwise how can the observed effect(s) be explained? This is the message drummed into students in many disciplines, even though statistical methods of experimental design which allow more than one variable to be altered at a time have been around since the 1940s!...

A rapid method is described for the detection of cellulolytic, thermophilic actinomycetes involving the use of a dyed cellulose substrate (cellulose-azure) in an agar medium. The test was performed in test tubes in which agar containing cellulose-azure was layered on top of a basal medium (mineral salts agar) resulting in two distinct layers. After...

A range of substrates has been examined in order to determine the types of attachment mechanism employed by marine bacteria. Use of the scanning electron microscope (SEM) has also allowed an investigation of the initimate relationship between an antifouling paint matrix and its attached bacterial community. Plastic (Thermanox) and glass coverslips,...

Poster presented at the 11th European Congress on Biotechnology, 24-29 August 2003, Basel, Switzerland

Poster presented at the 11th European Congress on Biotechnology, 24-29 August 2003, Basel, Switzerland.

UK Patent Application No. 0124433.2 (Filed 11th October 2001). Also published as WO03033411 (A1), EP1444167 (A1), EP1444167 (A0), CA2500843 (A1), AU2002334149 (A2).

Paper given at the International Water Association Conference, Cape Town, South Africa, 2003

Patent application filed 29th June 2001; granted 24th December 2002. Published 3rd June 2003. The present invention concerns the field of nitrification of fluids, and particularly relates to the treatment of aqueous fluids to oxidize ammonia and nitrites to produce nitrates. One aspect of the present invention seeks to provide an alternative nitrif...

Poster presented at the 11th European Congress on Biotechnology, 24-29 August 2003, Basel, Switzerland.

Poster presented at 4th World Water Congress of the International Water Association, Marrakech, Morocco, 19-24 September 2004

Poster presented at the 11th European Congress on Biotechnology, 24-29 August 2003, Basel, Switzerland.

UK Patent Application no. WO0024682 (filed October 1998). Also published as EP1129037 (A1), US6572773 (B1), EP1129037 (A0), CA2348520 (A1). The present invention concerns the field of nitrification of fluids, and particularly relates to the treatment of aqueous fluids to oxidize ammonia and nitrites to produce nitrates. One aspect of the present in...

Presented at the 147th Ordinary Meeting of the Society for General Microbiology, 12-15 September 2000, University of Exeter. An expanded bed, nitrifying bioreactor designed to remove ammonia from effluents has been in operation for several years. It was inoculated with a mixed microbial population from a nitrifying trickling filter, and it took sev...

Presented at the 147th Ordinary Meeting of the Society for General Microbiology, 12-15 September 2000, University of Exeter. Ammonia released into the aquatic environment causes a series of problems, including toxicity to fish and oxygen depletion through nitrification, with an increased risk of eutrophication through consequent nitrate production....

Presented at the joint Society for General Microbiology/Society for Applied Microbiology Millennium Meeting, University of Warwick, 10-14 April 2000. Groundwater normally has to be treated before it is suitable for potable use. For example by aeration, to supply oxygen; passage down through a sand filter, to filter out fine particulates and remove...

Presented at Bioscience 2005 (Biochemical Society meeting), Glasgow, July 17-21, 2005. Alkali tolerant fungus Aspergillus fischeri Fxn 1 secretes two xylanases, an exoxylanase (XylA) and an endoxylanase (XylB) in solid state fermentation. Kinetic studies showed that thermal inactivation of purified XylA and XylB at pH 9, in the temperature ranging...

Presented at the IWA Biofilm Technologies Conference, 8-10 January 2008, Singapore.