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Located on a cleared koppie called "Kolrand" in the Eastern Cape, the Karel Landman Monument (KLM) was designed by Gerhard Moerdijk. Its foundation was laid on 16 December 1938, and the monument itself was unveiled a year later. But rather than being a straightforward outgrowth of the celebrations that surrounded the Centenary of the Great Trek, it is revealed that the KLM was mired in controversy about Karel Landman's standing as a "Voortrekker" and the monument's legitimacy. It is argued also that, despite seeming unusual, it deploys visual tropes that can be discerned in other monuments that emanated from the Centenary Trek. Furthermore, it is proposed that its visual language is tied into Afrikaner imaginaries that held sway in the late 1930s. In its inclusion of a globe and its treatment of the trek motif within it, the KLM is underpinned by a conception of South Africa's place in the world that is at odds with a British imperialist vision of the Cape and Egypt as civilising points at either end of a dark hinterland. It would seem instead to be tied into conceptions of the heartland of Africa as an abode in which the white Afrikaner enjoys a God-given predominance and may perhaps even be linked to conceptions of Monomotapa which were an influence on Moerdijk.

Abstract The potential health risks associated with sludge cake application to agricultural land are managed by controlling the levels of Escherichia coli (E. coli) bacteria which indicate the risk of pathogen transfer. Analyses undertaken following post-digestion sludge dewatering have shown unpredictable levels of E. coli increase in stored sludge cake. Presently there is limited understanding on environmental parameters controlling the indicator bacteria density in storage and the contributory effects dewatering may have. This review aims to establish the state of current knowledge on innate and environmental factors influencing E. coli dynamics and survival in biosolids. A key factor identified is the effect of mechanical dewatering processes, which transform the sludge matrix environmental conditions through the increased availability of growth factors (e.g. nutrient and oxygen). Examples of storage practices from the agricultural and food industries are also discussed as successful methods to inhibit bacterial growth and survival, which could be extrapolated to the biosolids sector to regulate E. coli concentrations. Graphic Abstract

Ammonia is a common pollutant, present in municipal wastewater streams. With the continuous shift of people moving to cities and the growing world’s population, the overall wastewater amount is rising. Current ammonia treatment processes in wastewater treatment plants include biological nitrification. Here the ammonia is converted to nitrate or nitrogen. Unfortunately, the capital and operational expenditure costs of such processing are high and the ammonia is converted to products that have no value. Ammonia is a carbon-free energy carrier. Recently, technological solutions have been introduced to strip ammonia from wastewater [1]. The recovered ammonia can be electrochemically oxidised to benign nitrogen in an electrolyser, which can offer a cost-efficient technology to couple wastewater remediation at an anode with the production of a valuable by-product at the cathode, hydrogen. Currently, the commercialisation of the ammonia electrolyser technology is hindered by slow reactions at the anode and the cathode as well as the deactivation or degradation of the catalysts over time [2,3]. Consequently, the development of inexpensive, efficient anode material is imperative to reduce costs associated with ammonia destruction and electrochemical hydrogen production. This study focuses on a non-noble metal NiCu catalyst as a durable anode for alkaline ammonia electrolysis. We report that nickel-copper catalysts can oxidise ammonia to nitrogen at room temperature, see figure below. During electrolysis experiments, gas chromatography of the off-gases confirmed that both, nitrogen at the anode and hydrogen at the cathode, are generated with high faradaic efficiencies. Anode morphology and structure before and after electrolysis was investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), X-ray Photoelectron Spectroscopy (XPS), and scanning electron microscopy (SEM). To monitor possible intermediates produced by electrolysis, the electrolyte was analysed for NOx regularly by cuvette test and the electrode off-gasses were continuously monitored by GC-TCD. Overall, the electrode showed stability after continuous electrolysis in ammonia for over 30 hours. Further results will be presented at the conference. References: [1] L. Kinidi, I.A.W. Tan, N.B. Abdul Wahab, K.F.B. Tamrin, C.N. Hipolito, S.F. Salleh, Recent Development in Ammonia Stripping Process for Industrial Wastewater Treatment, International Journal of Chemical Engineering. 2018 (2018) 1–14. https://doi.org/10.1155/2018/3181087. [2] B. Zhou, N. Zhang, Y. Wu, W. Yang, Y. Lu, Y. Wang, S. Wang, An option for green and sustainable future: Electrochemical conversion of ammonia into nitrogen, Journal of Energy Chemistry. 60 (2021) 384–402. https://doi.org/10.1016/j.jechem.2021.01.011. [3] N.M. Adli, H. Zhang, S. Mukherjee, G. Wu, Review—Ammonia Oxidation Electrocatalysis for Hydrogen Generation and Fuel Cells, J. Electrochem. Soc. 165 (2018) J3130–J3147. https://doi.org/10.1149/2.0191815jes. Figure 1

This brief response must first acknowledge the generosity with which all the reviewers—Joel Quirk, Siphamandla Zondi, Heloise Weber, Audie Klotz, and Atul Mishra—have engaged with our book. Their r...

Hollow fibre membrane contactor (HFMC) technology has been developed for CO2 absorption primarily using synthetic gas, which neglects the critical impact that trace contaminants might have on separation efficiency and robustness in industrial gases. This study, therefore, commissioned a demonstration-scale HFMC for CO2 separation at a full-scale anaerobic digester facility to evaluate membrane integrity over six months of operation on real biogas. The CO2 capture efficiency identified using real biogas was benchmarked at comparable conditions on synthetic gas of an equivalent partial pressure, and an equivalent performance identified. Two HFMC were subsequently compared, one with and one without a pre-treatment stage that targeted particulates, volatile organic compounds (VOCs) and humidity. Similar CO2 separation efficiency was again demonstrated, indicating limited impact within the timescale evaluated. However, gas phase pre-treatment is advised in order to ensure robustness in the long term. Over longer-term operation, a decline in CO2 separation efficiency was observed. Membrane autopsy identified shell-side deposition, where the structural morphology and confirmation of amide I and II groups, indicated biofouling. Separation efficiency was reinstated via chemical cleaning, which demonstrated that proactive maintenance could minimise process risk.

International audience; Previous studies have found difficulties in reconciling mass transfer between membrane contactors of different geometries, which has been attributed to differences in fluid mixing. In this study, we compare the two most commonly adopted geometries (parallel and transverse flow) and use residence time distribution (RTD) analysis to verify the influence of geometry on fluid mixing in addition to developing a generalized correlation that can collectively describe mass transfer for both geometries. Lumen-side mass transfer was well described by the Lévêque solution in well-developed laminar conditions for both parallel and transverse flow modules. However, considerably lower mass transfer was identified for shell-side flow in the parallel fiber configuration, with RTD analysis providing confirmation that this was due to shell-side bypass which reduced mean fluid residence time (τ=v/L) in the contactor to below that of the theoretical residence time. The mean residence time calculated from RTD analysis enabled reconciliation of mass transfer data between both geometries, such that mass transfer could be adequately described for both configurations using: Shs=1.27Re0.793Sc0.33(dh/L). The Reynolds number exponent indicated transitional mass transfer despite operation firmly within the laminar regime, which would indicate an enhancement in mass transfer provided by secondary flow effects within tightly packed fiber bundles. Whilst previously observed, for example in heat transfer analogies, such dependencies are generally more closely associated with parallel flow rather than ‘classical’ cross-flow modules in which fluid flow is explicitly perpendicular to the fiber bundle, and indicates that mass transfer in transverse flow may be better described as parallel flow, which confirms previous assumptions. Importantly, this study demonstrates the capability to reconcile mass transfer between modules of different geometries and permits the opportunity to project process design and scale-up between the two most commonly applied membrane contactor module geometries.