Analytical Assessment of Dissolved Organic Nitrogen in an Industrial Wastewater Treatment Plant

Abstract

The Industrial Emission Directive (IED) aims to reduce the environmental impact from a wide range of industrial activities, including the pharmaceutical industry. In this research, partnership with Alpheus Environmental Ltd company the operators of GlaxoSmithKline’s (GSK) wastewater treatment plant (WWTP) in Irvine, Scotland. The site produces bulk β-lactam antibiotics such as 6-aminopenicillanic acid and clavulanic acid. As the production of β-lactam antibiotics represents around 70% of world market share. The wastewater generated from these facilities are generally characterised with high levels of suspended solids and dissolved organic compounds, however, characterisation of such wastewater across an activated sludge treatment plant was lacking. The aim of this thesis is to characterise the physicochemical properties of the wastewater across GSK’s WWTP and to distinguish the contribution of both dissolved inorganic nitrogen and dissolved organic nitrogen (DON) to high total nitrogen (TN) in WWTP effluents of the β-lactam antibiotic production facility. This research was carried out in three phases. The first research phase was to analyse the samples collected from four points across GSK’s activated sludge treatment plant for gross physicochemical properties. The second phase was to analyse the collected samples specifically for chitin and glucosamine concentration in GSK’s effluent samples. The third research phase was to assess the bioavailability and toxicity of GSK’s secondary effluents to green microalgae R. subcapitata. The characterisation of the wastewater across the WWTP showed that dissolved organic nitrogen represented 36% of the total nitrogen concentration. Glucosamine average concentrations in secondary clarifiers and final tank effluents were 14 mg/l and 18 mg/l, respectively. This accounted only for 16% and 18% of DON concentration, which indicates that glucosamine represented a considerable part of the DON fraction; however, more work is needed to identify the remaining of DON constituents. Additionally, the results showed a relationship between glucosamine concentration and fulvous colour intensity in effluent samples collected from the various sampling points across the WWTP. The bioavailability test showed that R. subcapitata had grown exponentially on secondary clarifiers samples after an adaptation time, however, the growth in diluted samples and on glucosamine as a sole nutrient was limited. In conclusion, this work confirms the importance of considering the dissolved organic nitrogen concentration in industrial wastewater effluent for compliance purposes. However, this work showed that characterisation of DON could lead to the opportunity of identifying the major sources of organic nitrogen compounds in the industrial effluents and developing new strategies to improve inorganic and organic nitrogen removal from the system by enhancing the biological treatment process.