Using Constructed Wetlands to Remove Pathogenic Parasites and Fecal Coliforms from Wastewater in Dar es Salaam and Iringa, Tanzania

Wastewater treatment is a widely used health protection measure that can be applied to control the transmission of wastewater-related infectious diseases to communities exposed to wastewater. This study determined the efficiency of three full-scale constructed wetlands (CWs) in removing pathogenic parasites and fecal coliform (FC) bacteria from wastewater. Wastewater samples were collected from three CW systems located in the Dar es Salaam and Iringa regions of Tanzania. The modified Bailenger and modified Ziehl-Neelsen stain techniques were used to detect and quantify parasites. The membrane filtration method was used to detect and quantify FC bacteria. Data were analysed using IBM SPSS version 20. Helminth (Ascaris lumbricoides, hookworm, and Taenia spp.) eggs were completely removed by two CW systems. In all the systems, the removal of protozoa ranged from 99.8% to 100%. The mean concentrations of FCs in effluents ranged from 5 to 6 log units/100 mL. Effluents of all CW systems met the recommended parasitological quality requirements of the World Health Organization for the safe reuse of wastewater. FC effluents concentrations did not meet the local discharge standards of the Tanzania Bureau of Standards. Therefore, improvement to the CWs’ design, operation, and maintenance are required for the efficient removal of bacteria. Keywords: helminth, protozoa, fecal coliform, wastewater treatment, constructed wetlan

Natural Wastewater Treatment Systems for Prevention and Control of Soil-Transmitted Helminths

Wastewater reuse has been considered as an alternative way of overcoming water scarcity in many parts of the world. However, exposures to wastewater are associated with higher prevalence of soil-transmitted helminths (STHs). Globally, about two billion people are infected with at least one species of STHs with those having heavy infections presenting considerable morbidities. The most serious STH species infecting humans include roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), and hookworms (Necator americanus and Ancylostoma duodenale). Despite ongoing control campaigns using preventive chemotherapy, wastewater in endemic countries still contains concentrations of STH eggs that put exposed populations at risk of infection. According to the World Health Organization, we can achieve sustainable control of STH by using improved sanitation systems. Since natural wastewater treatment systems (waste stabilization ponds and constructed wetlands) require low maintenance and operational costs, have low mechanical technology and energy consumption, they are ideal for sustainable sanitation services. In addition, natural wastewater treatment systems are reported to efficiently remove various pathogenic organisms from wastewater. This chapter explains the role of natural wastewater treatment systems as sustainable sanitation facilities in removing STH from wastewater and therefore preventing disease transmission

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

Mass transfer approach and the designing of horizontal subsurface flow constructed wetland systems treating waste stabilisation pond effluent

Pilot-scale constructed wetlands (CWs) that allowed wastewater to flow with high interstitial velocities in a controlled environment were used to evaluate the possibility of using mass transfer approach to design horizontal subsurface flow constructed wetlands (HSSF-CWs) treating waste stabilisation ponds (WSPs) effluent. Since CW design considers temperature which is irrelevant in tropics, mass transfer approach could improve the design. HSSF-CWs were operated in batch recycle mode as continuous stirred tank reactors (CSTR) at different interstitial velocities. The overall removal rate constants of chemical oxygen demand (COD) at various interstitial velocities were evaluated in mesocosms that received pretreated domestic wastewater. The mean overall removal rate constants were 0.43, 0.69, 0.74 and 0.73 d-1 corresponding to interstitial velocities of 15.43, 36, 56.57 and 72 md-1, respectively. Results showed that the interstitial velocities up to 36 md-1 represented a range where mass transfer effect was significant and, above it, insignificant to the COD removal process. Since WSPs effluent has high flow rates and low organic load, it is possible to induce high interstitial velocities in a HSSF-CW treating this effluent, without clogging and overflow. The performance of these HSSF for tertiary treatment in tropical areas could be improved by considering flow velocity when designing.status: publishe