Gertjan Medema

Gertjan Medema
KWR Watercycle Research Institute - Delft University of Technology · Water Quality & Health - Sanitary Engineering

PhD

About

240
Publications
64,165
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Introduction
My research field explores the (mitigation of the) spread of infectious diseases through water. It studies the behaviour and fate of pathogenic micro-organisms (viruses, bacteria, parasites, antibiotic resistance) in water, aerosols, sludge, soil and water treatment processes. I aim to quantify human exposure to pathogenic micro-organisms through water (drinking, bathing water, wastewater, sludge, aerosols) and translate this to human health risks by QMRA and to water management interventions.

Publications

Publications (240)
Preprint
Full-text available
Background: Despite high vaccination rates in the Netherlands, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to circulate. Longitudinal sewage monitoring was implemented along with the notification of cases as two parts of the surveillance pyramid to validate the use of sewage surveillance for monitoring SARS-CoV-2, as an e...
Article
Electrochemical ferrous iron (Fe²⁺) wastewater treatment is gaining momentum for treating municipal wastewater due to its decreasing costs, environmental friendliness and capacity for removal of a wide range of contaminants. Disinfection by iron electrocoagulation (Fe-EC) has been occasionally reported in full scale industrial applications, yet con...
Article
Full-text available
Irrigation with surface water carrying plant pathogens poses a risk for agriculture. Managed aquifer recharge enhances fresh water availability while simultaneously it may reduce the risk of plant diseases by removal of pathogens during aquifer passage. We compared the transport of three plant pathogenic bacteria with Escherichia coli WR1 as refer...
Article
Full-text available
The aperiodic changes in the quantity and community of planktonic and particle-associated bacteria have hampered the understanding and management of microbiological water quality in drinking water distribution systems. In this study, online sampling was combined with the microbial fingerprint-based SourceTracker2 to capture and trace the spatiotemp...
Article
For community-level monitoring, the European Commission under the EU Sewage Sentinel System recommends wastewater-based SARS-CoV-2 surveillance. Tracking SARS-CoV-2 variants in a community is pivotal for appropriate public health response. Genome sequencing of SARS-CoV-2 in wastewater samples for tracking variants is challenging, often resulting in...
Preprint
Over the course of the COVID-19 pandemic in 2020-2021, monitoring of SARS-CoV-2 RNA in wastewater has rapidly evolved into a supplementary surveillance instrument for public health. Short term trends (2 weeks) are used as a basis for policy and decision making on measures for dealing with the pandemic. Normalization is required to account for the v...
Article
Full-text available
Risk assessment is critical for identifying target concentrations of antibiotic resistant pathogens necessary for mitigating potential harmful exposures associated with water reuse. However, there is currently limited available data characterizing the concentrations of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in re...
Article
Minimum treatment requirements are set in response to established or anticipated levels of enteric pathogens in the source water of drinking water treatment plants (DWTPs). For surface water, contamination can be determined directly by monitoring reference pathogens or indirectly by measuring fecal indicators such as Escherichia coli (E. coli). In...
Article
Full-text available
Wastewater surveillance has shown to be a valuable and efficient tool to obtain information about the trends of COVID-19 in the community. Since the recent emergence of new variants, associated with increased transmissibility and/or antibody escape (variants of concern), there is an urgent need for methods that enable specific and timely detection...
Article
Full-text available
Wastewater surveillance for pathogens using reverse transcription-polymerase chain reaction (RT-PCR) is an effective and resource-efficient tool for gathering additional community-level public health information, including the incidence of coronavirus disease-19 (COVID-19). Surveillance of SARS-CoV-2 in wastewater can provide an early warning signa...
Article
Full-text available
Faecal pathogens can be introduced into surface water through open defecation, illegal disposal and inadequate treatment of faecal sludge and wastewater. Despite sanitation improvements, poor countries are progressing slowly towards the United Nation's Sustainable Development Goal 6 by 2030. Sanitation-associated pathogenic contamination of surface...
Preprint
Full-text available
Wastewater based surveillance employing qPCR has already shown its utility for monitoring SARS-CoV-2 at community level, and consequently the European Commission has recommended the implementation of an EU Sewage Sentinel System. However, using sequencing for the determination of genomic variants in wastewater is not fully established yet. Therefor...
Technical Report
Vol 2 describes ten ASR sites 5 in USA, 4 in Australia and 1 in Netherlands thet were used to inform the volume 1 Synthesis of water quality improvements during Aquifer Storage and Recovery
Article
Full-text available
Managed aquifer recharge (MAR) can provide irrigation water and overcome water scarcity in agriculture. Removal of potentially present plant pathogens during MAR is essential to prevent crop diseases. We studied the die-off of three plant pathogenic bacteria in water microcosms with natural or filtered tile drainage water (TDW) at 10 and 25°C and w...
Article
Full-text available
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly become a major global health problem, and public health surveillance is crucial to monitor and prevent virus spread. Wastewater-based epidemiology has been proposed as an addition to disease-based surveillance because virus is shed in the feces of ≈40% of infected persons. We...
Article
A monitoring strategy was implemented at two drinking water treatment plants in Quebec, Canada, to evaluate microbial reduction performances of full-scale treatment processes under different source water conditions. β-D-glucuronidase activity in source water was automatically monitored in near-real-time to establish baseline and event conditions at...
Preprint
Full-text available
Wastewater surveillance for pathogens using the reverse transcription-polymerase chain reaction (RT-PCR) is an effective, resource-efficient tool for gathering additional community-level public health information, including the incidence and/or prevalence and trends of coronavirus disease-19 (COVID-19). Surveillance of SARS-CoV-2 in wastewater may...
Article
The presence of SARS-CoV-2 RNA in wastewater was first reported in March 2020. Over the subsequent months, the potential for wastewater surveillance to contribute to COVID-19 mitigation programmes has been the focus of intense national and international research activities, gaining the attention of policy makers and the public. As a new application...
Preprint
Wastewater surveillance has shown to be a valuable and efficient tool to obtain information about the trends of COVID-19 in the community. Since the recent emergence of new variants, associated with increased transmissibility and/or antibody escape (variants of concern), there is an urgent need for methods that enable specific and timely detection...
Preprint
A year since the declaration of the global coronavirus disease 2019 (COVID-19) pandemic there have been over 110 million cases and 2.5 million deaths. Using methods to track community spread of other viruses such as poliovirus, environmental virologists and those in the wastewater based epidemiology (WBE) field quickly adapted their existing method...
Article
Full-text available
Wastewater treatment is challenged by the continuous emergence of chemical and biological contaminants. Disinfection, advanced oxidation, and activated carbon technologies are accessible in high-income countries to suppress them. Low-cost, easily implementable, and scalable solutions are needed for sanitation across regions. We studied the properti...
Article
Full-text available
Slow sand filters (SSFs) are widely applied to treat potable water; the removal of contaminants (e.g., particles, organic matter, and microorganism) occurs primarily in the top layer. However, the development of the microbial community and its metabolic function is still poorly understood. In the present study, we analyzed the microbial quantity an...
Article
Full-text available
This study investigates short-term fluctuations in virus concentrations in source water and their removal by full-scale drinking water treatment processes under different source water conditions. Transient peaks in raw water faecal contamination were identified using in situ online β-D-glucuronidase activity monitoring at two urban drinking water t...
Article
Full-text available
The water sector needs to address viral-related public health issues, because water is a virus carrier, which not only spreads viruses (e.g., via drinking water), but also provides information about the circulation of viruses in the community (e.g., via sewage). It has been widely reported that waterborne viral pathogens are abundant, diverse, comp...
Article
Full-text available
In this paper we analyse the feasibility of low voltage iron electrocoagulation as a means of municipal secondary effluent treatment with a focus on removal of microbial indicators, Antibiotic Resistant Bacteria (ARB) and nutrients. A laboratory scale batch unit equipped with iron electrodes was used on synthetic and real secondary effluent from a...
Article
Full-text available
Drinking water distribution systems (DWDSs) have been thoroughly studied, but the concept of thermal energy recovery from DWDSs is very new and has been conceptualized in the past few years. Cold recovery results in a temperature increase of the drinking water. Its effects on drinking water quality and biofilm development are unclear. Hence, we stu...
Article
Full-text available
Cu and Ag have been used as bactericidal agents since ancient times, yet their antiviral capacity in water remains poorly understood. This study tested the effect of copper (Cu) and silver (Ag) on model RNA and DNA viruses MS2 and PhiX 174 in solution at pH 6e8. Cu caused MS2 inactivation with similar rates at pH 6 and 7 but was inert towards PhiX...
Article
Temporal variations in concentrations of pathogenic microorganisms in surface waters are well known to be influenced by hydrometeorological events. Reasonable methods for accounting for microbial peaks in the quantification of drinking water treatment requirements need to be addressed. Here, we applied a novel method for data collection and model v...
Article
Analysing wastewater can be used to track infectious disease agents that are shed via stool and urine. Sewage surveillance of SARS-CoV-2 has been suggested as a tool to determine the extent of COVID-19 in cities and serve as an early warning for (re-)emergence of SARS-CoV-2 circulation in communities. The focus of this review is on the strength of...
Article
The identification of appropriately conservative statistical distributions is needed to predict microbial peak events in drinking water sources explicitly. In this study, Poisson and mixed Poisson distributions with different upper tail behaviors were used for modeling source water Cryptosporidium and Giardia data from 30 drinking water treatment p...
Preprint
Full-text available
The current SARS-CoV-2 pandemic has rapidly become a major global health problem for which public health surveillance is crucial to monitor virus spread. Given the presence of viral RNA in feces in around 40% of infected persons, wastewater-based epidemiology has been proposed as an addition to disease-based surveillance to assess the spread of the...
Preprint
Full-text available
Disinfection of treated wastewater in wastewater treatment plants (WWTPs) is used to minimize emission of coliforms, pathogens, and antibiotic resistant bacteria (ARB) in the environment. However, the fate of free-floating extracellular DNA (eDNA) that do carry antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) is overlooked. Wat...
Article
Probabilistic quantitative microbial risk assessment (QMRA) studies define model inputs as random variables and use Monte-Carlo simulation to generate distributions of potential risk outcomes. If local information on important QMRA model inputs is missing, it is widely accepted to justify assumptions about these model inputs by using external liter...
Article
As many regions seek to supplement traditional water sources with reclaimed water, an increasing number of risk assessments are conducted for these types of applications. The most comprehensive approach is to conduct a quantitative microbial risk assessment (QMRA) combining empirical and literature data, point value estimates, and probability distr...
Article
Full-text available
Bivins, Aaron et al. "Wastewater-Based Epidemiology: Global Collaborative to Maximize Contributions in the Fight Against COVID-19." Environmental Science & Technology (June 2020) © 2020 American Chemical Society
Technical Report
Full-text available
This technical brief provides information to inform water, sanitation and hygiene (WASH) and wastewater elements within multi-sectoral antimicrobial resistance (AMR) national action plans (NAPs). It includes a summary of evidence and the co-benefits rationale for action in each sector and presents a menu of actions for consideration and refinement...
Presentation
Researchers around the world are currently exploring ways that wastewater samples can help us understand the spread of COVID-19 at a community scale. The Water Science and Technology Board will host a panel discussion with experts on public health and wastewater monitoring to discuss the potential value of data on SARS-CoV-2 in wastewater to inform...
Article
In the current COVID-19 pandemic, a significant proportion of cases shed SARS-Coronavirus-2 (SARS-CoV-2) with their faeces. To determine if SARS-CoV-2 RNA was present in sewage during the emergence of COVID-19 in the Netherlands, sewage samples of six cities and the airport were tested using four qRT-PCR assays, three targeting the nucleocapsid gen...
Article
Full-text available
Freshwater is a precious resource, and shortages can lead to water stress, impacting agriculture, industry, and other sectors. Wastewater reuse is increasingly considered as an opportunity to meet the freshwater demand. Legislative frameworks are under development to support the responsible reuse of wastewater, i.e., to balance benefits and risks....
Article
Full-text available
In the present study, triplicate rings of 360-degrees pipe surface of an operational drinking water distribution pipe were swabbed. Each ring was equally divided into 16 parts for swabbing. The collected swabs were grouped into 3 sections and compared with the biofilm samples sampled by sonication of specimens from the same pipe. The results showed...
Preprint
In the current COVID-19 pandemic, a significant proportion of cases shed SARS-Coronavirus-2 (SARS-CoV-2) with their faeces. To determine if SARS-CoV-2 is present in sewage during the emergence of COVID-19 in the Netherlands, sewage samples of 7 cities and the airport were tested using RT-PCR against three fragments of the nucleocapsid protein gene...
Article
Full-text available
Antibiotic resistant bacteria (ARB) and resistance genes (ARGs) are abundant in stormwater, yet there is no consensus regarding how to assess their public health risks. We systematically reviewed the literature and identified 15 studies that provided quantitative occurrence and/or abundance information that was linked to stormwater. Sampling and da...
Article
Full-text available
Drinking water distribution systems (DWDSs) are used to supply hygienically safe and biologically stable water for human consumption. The potential of thermal energy recovery from drinking water has been explored recently to provide cooling for buildings. Yet, the effects of increased water temperature induced by this "cold recovery" on the water q...
Article
Full-text available
Ceramic pot filters are household water treatment and safe storage (HWTS) systems designed to improve the microbial quality of drinking water. They yield high log reduction values (LRVs) for bacterial and protozoan pathogens but provide very little removal of viruses. This study investigated virus removal of ceramic filter discs (CFDs), using feed...
Article
Full-text available
Background: A community-wide outbreak of Legionnaires' disease (LD) occurred in Genesee County, Michigan, in 2014 and 2015. Previous reports about the outbreak are conflicting and have associated the outbreak with a change of water source in the city of Flint and, alternatively, to a Flint hospital. Objective: The objective of this investigation...
Article
In several jurisdictions, the arithmetic mean of Escherichia coli concentrations in raw water serves as the metric to set minimal treatment requirements by drinking water treatment plants (DWTPs). An accurate and precise estimation of this mean is therefore critical to define adequate requirements. Distributions of E. coli concentrations in surface...
Poster
Full-text available
Ceramic pot filters (CPFs) are household water treatment systems designed to improve the microbial quality of drinking water. They yield high removal values for bacterial and protozoan pathogens but provide very little removal of viruses. Reported virus removal in CPFs was hypothesized to be due to the growth of biofilms on the filter, following a...
Article
The aim of this study was to capture and explain changes in antibiotic resistance gene (ARG) presence and concentration internationally across the Rhine river. Intl1 concentrations and national antibiotic usage were investigated as proxies to predict anthropogenic ARG pollution. Newly-developed multiplex qPCR assays were employed to investigate ARG...
Article
Full-text available
Worldwide, it is common that the drinking water distribution systems (DWDSs) may be subjected to changes of supply water quality due to the needs of upgrading the treatment processes or switching the source water. However, the potential impacts of quality changed supply water on the stabilized ecological niches within DWDSs and the associated water...
Conference Paper
Microbial safety of drinking water is of utmost importance for health. In many regions of the world, water shortage leads to direct or indirect reuse of wastewater or use of other unsafe water sources. Quantitative Microbial Risk Assessment (QMRA) can be used to determine which combination of water treatment processes is needed to provide safe wate...
Poster
Full-text available
In surface- and wastewater management it is important to determine the origin of the water and of the potentially problematic substances/organisms it might contain. These are faecal contamination, nutrient-related questions, or malfunctioning wastewater treatment plants (WWTPs). This research examines the possible contribution of the DNA fingerprin...
Article
The United Nations’ Sustainable Development Goals initiated in 2016 reiterated the need for safe water and healthy lives across the globe. The tenth anniversary meeting of the International Water and Health Seminar in 2018 brought together experts, students, and practitioners, setting the stage for development of an inclusive and evidence-based res...
Article
Full-text available
To ensure delivery of microbiologically safe drinking water, the physical integrity of the distribution system is an important control measure. During repair works or an incident the drinking water pipe is open and microbiologically contaminated water or soil may enter. Before taking the pipe back into service it must be cleaned. The efficacy of fl...
Preprint
The United Nations' Sustainable Development Goals initiated in 2016 reiterated the need for safe water and healthy lives across the globe. The tenth anniversary meeting of the International Water and Health Seminar in 2018 brought together experts, students, and practitioners, setting the stage for development of an inclusive and evidence-based res...
Article
Averaged 7-day composite effluent wastewater samples from twelve wastewater treatment plants (WWTPs) in nine countries () in the Danube River Basin were collected. WWTPs' selection was based on countries' dominant technology and a number of served population with the aim to get a representative holistic view of the pollution status. Samples were an...
Article
Wastewater is an important resource in water-scarce regions of the world, and its use in agriculture requires the guarantee of acceptable public health risks. The use of fecal indicator bacteria to evaluate safety does not represent viruses, the main potential health hazards. Viral pathogens could complement the use of fecal indicator bacteria in t...
Article
Full-text available
p> The protozoan pathogen Cryptosporidium is an important cause of diarrhoeal disease, but in many contexts its burden remains uncertain. The Global Waterborne Pathogen model for Cryptosporidium (GloWPa-Crypto) predicts oocyst concentrations in surface water at 0.5 by 0.5° (longitude by latitude) resolution, allowing us to assess the burden specifi...
Article
Full-text available
The water sector is, currently and for the foreseeable future, challenged by rising levels of uncertainty in demand and availability of water, in a context of aging infrastructure and limited investment. In order to support strategic planning, water companies need a way to assess how their system behaves when faced with a range of changing conditio...
Article
Diarrhoea caused by waterborne pathogens still has a large burden of disease. We introduce a modelling and scenario analysis framework that enables better understanding of sources of and possible future changes in the disease burden due to environmental change and management implementation. The state-of-the-art research that can contribute to the d...