Bioscience for renewable resources and clean growth

Microbial biotechnology approaches to optimize chemical oxygen demand and enhance nitrogen and phosphorus removal in wastewater treatment

Primary Supervisor

Prof Jeremy Webb- University of Southampton


Dr Yongqiang Liu – University of Southampton

Juhani Kostiainen – Plantworks System Limited


More stringent allowances for nutrient discharge from municipal wastewater treatment plants are being gradually implemented in the UK to protect natural water bodies

However, complying with this regulation relies heavily on the dosing of a large amount of chemicals, creating more problems in terms of nutrient removal cost, sludge management and environmental sustainability. Therefore, chemical-free biological treatment is urgently needed for cost-effective and sustainable nutrient removal. By collaborating with PlantWorks System Ltd (PWS), this Ph.D. project proposes to optimize and enhance simultaneous removal of chemical oxygen demand (COD), nitrogen (N) and phosphorus (P) from municipal wastewater with sequential batch reactor (SBR) technology by deepening understanding of microorganisms involved for N and P removal, of relevant metabolisms, of mass transfer and hydrodynamics.  Two large-scale SBRs with a volume of 50 m3 will be operated with one focusing on biological COD and P removal while the other on biological COD, N and P removal. The specific objectives of the project include 1)  identifying key functional microorganisms in the SBRs for N and P removal under different conditions and correlating them with relevant nutrient metabolisms, sludge morphology such as flocs and granules, and sludge settleability; 2) optimizing the operation of the upstream unit of SBRs, i.e. balancing tank (fermenter), by investigating acetogenic metabolism, off-gas compositions, oxidation-reduction potential (ORP), hydrodynamics and mixing; 3) cultivating and enriching microorganisms for non-reactive soluble P removal and exploring the bioaugmentation potential for the enhancement of biological P removal; 4) developing dissolved oxygen (DO) control strategies to quickly respond to the changes in DO demand for N and P removal, thus reducing aeration cost. The work will combine water process engineering with a microbiological investigation to underpin fundamentals for the optimization and enhancement of biological municipal wastewater treatment in SBRs without any chemicals, and thus ultimately to achieve holistic sustainability of wastewater treatment when protecting water bodies.