Establishment of local wastewater-based surveillance programmes in response to the spread and infection of COVID-19 - case studies from South Africa, the Netherlands, Turkey and England

The COVID-19 pandemic has resulted in over 340 million infection cases (as of 21 January 2022) and more than 5.57 million deaths globally. In reaction, science, technology and innovation communities across the globe have organised themselves to contribute to national responses to COVID-19 disease. A significant contribution has been from the establishment of wastewater-based epidemiological (WBE) surveillance interventions and programmes for monitoring the spread of COVID-19 in at least 55 countries. Here, we examine and share experiences and lessons learnt in establishing such surveillance programmes. We use case studies to highlight testing methods and logistics considerations associated in scaling the implementing of such programmes in South Africa, the Netherlands, Turkey and England. The four countries were selected to represent different regions of the world and the perspective based on the considerable progress made in establishing and implementing their national WBE programmes. The selected countries also represent different climatic zones, economies, and development stages, which influence the implementation of national programmes of this nature and magnitude. In addition, the four countries' programmes offer good experiences and lessons learnt since they are systematic, and cover extensive areas, disseminate knowledge locally and internationally and partnered with authorities (government). The programmes also strengthened working relations and partnerships between and among local and global organisations. This paper shares these experiences and lessons to encourage others in the water and public health sectors on the benefits and value of WBE in tackling SARS-CoV-2 and related future circumstances.

Real-time process dynamics monitoring in Anammox reactors

Process dynamics in Anammox systems were evaluated through continuous monitoring of pH, oxidation reduction potential (ORP) and conductivity in two separate newly started-up sequencing batch reactors, one seeded with an enriched Anammox sludge and the other seeded with mixed activated sludge. The pH and ORP profiles exhibited characteristic patterns depending on the process dynamics during early start-up, start-up and enrichment phases of the operational period of 410 days. The simultaneously continuing processes of the start-up period showed apparent indicative trend lines in pH and ORP profiles. Conductivity profiles were consistent with the process dynamics in all phases. During the enrichment phase, conductivity decreases could quantitatively be related to process removal efficiencies and all real-time profiles exhibited specific break-points which coincided with the end of Anammox in each cycle. The end of Anammox was observed as an 'apex' on pH profiles and a 'valley' on ORP profiles. The 'apex' and 'valley' points exactly coincided with the end point of the linear decrease in the conductivity profiles. The overall findings suggested a great potential in using real-time pH, ORP and conductivity measurements for quick and reliable monitoring of Anammox systems during start-up and enrichment periods.

Cometabolic degradation and inhibition kinetics of 1,2-dichloroethane (1,2-DCA) in suspended-growth nitrifying systems

Cometabolic degradation of 1,2-dichloroethane (1,2-DCA) and its inhibitory impact on nitrification were investigated by the use of a mixed suspended-growth culture enriched for nitrifiers. 1,2-DCA was found to be cometabolically degradable by the nitrifier culture. This degradation rate was found to be dependent on the initial 1,2-DCA level. The first-order 1,2-DCA degradation rate constants ranged between 0.42 and 0.87 L (g VSS)(-1) h(-1). Increase in NH4-N utilization favoured cometabolic degradation of 1,2-DCA. The amount of 1,2-DCA degraded per unit mass of NH4-N strongly correlated with initial NH4-N and 1,2-DCA concentrations, ranging between 50 mg L(-1) and 200 mg L(-1) and 1600 microg L(-1) and 100,000 microg L(-1), respectively. The presence of 1,2-DCA caused inhibition of oxygen uptake and NH4-N utilization. In spite of the adverse effect of 1,2-DCA on the nitrifying biomass, the system had a high capacity for cometabolic removal of this compound even at inhibitory concentrations. 1,2-DCA had mainly mixed inhibitor characteristics, but at low concentrations (< 25,000 microg/L) it acted rather as a competitive inhibitor. The inhibition constants belonging to 1,2-DCA, K(ic) (the dissociation constant of the enzyme-inhibitory compound complex) and K(iu) (the dissociation constant of the enzyme-substrate-inhibitory compound complex) were determined to be 6000-8000 microg L(-1) and 188,000-200,000 microg L(-1), respectively.

Biological removal of the xenobiotic trichloroethylene (TCE) through cometabolism in nitrifying systems

In the present study, cometabolic TCE degradation was evaluated using NH(4)-N as the growth-substrate. At initial TCE concentrations up to 845 microg/L, TCE degradation followed first-order kinetics. The increase in ammonium utilization rate favored the degradation of TCE. This ensured that biological transformation of TCE in nitrifying systems is accomplished through a cometabolic pathway by the catalysis of non-specific ammonia oxygenase enzyme of nitrifiers. The transformation yield (T(y)) of TCE, the amount of TCE degraded per unit mass of NH(4)-N, strongly depended on the initial NH(4)-N and TCE concentrations. In order to allow a rough estimation of TCE removal and nitrification at different influent TCE and NH(4)-N concentrations, a linear relationship was developed between 1/T(y) and the initial NH(4)-N/TCE ratio. The estimated T(y) values lead to the conclusion that nitrifying systems are promising candidates for biological removal of TCE through cometabolism.

Inhibitory effect of the xenobiotic 1,2-dichloroethane in a nitrifying biofilm reactor

The aim was to investigate the inhibitory effect of the xenobiotic 1,2-DCA on nitrification during the cometabolic degradation in a packed bed nitrifying biofilm reactor. This xenobiotic inhibited primarily the conversion of NH4-N to hydroxylamine by binding to the AMO enzyme. It had no inhibitory effect on the conversion of nitrite to nitrate. At high NH4-N loadings, the presence of 1,2-DCA inhibited NH4-N utilisation more severely than at low loadings. The suppressing effect of 1,2-DCA on NH4-N utilisation was found to be reversible due to the ability of cells to recover from inhibition. These results could fill a gap in the literature about the potential use of nitrifying biofilm systems for cometabolic treatment of 1,2-DCA and could be useful in the design of engineered 1,2-DCA remediation/treatment in biofilm reactors.