36 research outputs found
Spatio-temporal dynamics of virus and bacteria removal in dual-media contact-filtration for drinking water
Microorganism removal efficiencies in deep bed filters vary with time and depth in the filter bed as the
filter collects particles. Improved knowledge of such dynamics is relevant for the design, operation and
microbial risk assessment of filtration processes for drinking water treatment. Here we report on a highresolution
spatio-temporal characterization of virus and bacteria removal in a pilot-scale dual-media
filter, operated in contact-filtration mode. Microorganisms investigated were bacteriophage Salmonella
typhimurium 28B (plaque assay, n ¼ 154)), fRNA phage MS2 (plaque assay/RT-qPCR, n ¼ 87) and E. coli
(Colilert-18, n ¼ 73). Microscopic and macroscopic filtration models were used to investigate and
characterize the removal dynamics.
Results show that ripening/breakthrough fronts for turbidity, viruses and E. coli migrated in a wavelike
manner across the depth of the filter. Virus removal improved continuously throughout the filter
cycle and viruses broke through almost simultaneously with turbidity. Ripening for E. coli took longer
than ripening for turbidity, but the bacteria broke through before turbidity breakthrough. Instantaneous
log-removal peaked at 3.2, 3.0 and 4.5 for 28B, MS2 and E. coli, respectively. However, true average logremoval
during the period of stable effluent turbidity was significantly lower at 2.5, 2.3 and 3.6,
respectively. Peak observed filter coefficients l were higher than predicted by ideal filtration theory. This
study demonstrates the importance of carefully designed sampling regimes when characterizing
microorganism removal efficiencies of deep bed filters.Research Council of Norway (grant no. 226750/O30) and Norconsult AS consultancy firm14 Página
Concentrations and Retention Efficiency of Tire Wear Particles from Road Runoff in Bioretention Cells
Bioretention cells are popular stormwater management systems for controlling peak runoff and improving runoff water quality. A case study on a functional large-scale bioretention cell and a laboratory column experiment was conducted to evaluate the concentrations and retention efficiency of bioretention cells towards tire wear particles (TWP). The presence of TWP was observed in all soil fractions (500 µm) of the functional bioretention cell. TWP concentrations were higher (30.9 ± 4.1 mg/g) close to the inlet to the bioretention cell than 5 m away (19.8 ± 2.4 mg/g), demonstrating the influence of the bioretention cell design. The column experiment showed a high retention efficiency of TWP (99.6 ± 0.5%) in engineered soil consisting of sand, silty-sand, and garden waste compost. This study confirmed that bioretention cells built with engineered soil effectively retained TWP > 25 µm in size, demonstrating their potential as control measures along roads.publishedVersio
Microplastics concentrations in soil along a racetrack
Motorsport is known for its high tire wear due to speed, cornering, and high acceleration/deceleration activities. However, studies on the generation of microplastics from racetracks are rare. This study aimed at quantifying microplastics concentrations in topsoil (0–5 cm) along a racetrack. The results showed that rubber materials (RM) and tire reinforcement microplastics (TRMP) were deposited in the soil along the racetrack. Concentrations of the two microplastics were affected by the distance from the edge of the racetrack (highest concentrations within 20 cm from the track) and track alignment (highest concentrations at the start/finish area). In addition, a weak correlation was observed between the concentrations of the two microplastics, suggesting the effect of track alignment on the type of microplastics abraded. The results also showed that coarser microplastics (1000–5000 μm) dominate the size distribution of microplastics along a racetrack. The findings of this study may provide racetrack managers with basic information for designing microplastic-controlling solutions. While additional studies are required to map environmental effects and policy measures, our initial results suggest that motorsport is of concern in terms of microplastics release to the environment.Microplastics concentrations in soil along a racetrackpublishedVersio
Quantitative microbial risk assessment of wastewater and faecal sludge reuse in Ghana
The probabilistic health risks of rotavirus and Ascaris infections associated with different scenarios of
diluted wastewater and faecal sludge agricultural reuse in Ghana were estimated based on the Quantitative
Microbial Risk Assessment (QMRA) approach. The annual risks of rotavirus and Ascaris infections
associated with diluted wastewater reuse scenarios were 10-2 and 10-3 to 10-4 respectively compared with
the WHO tolerable health risk of 10-4 per person per year. The risk of Ascaris infection for the different
scenarios of faecal sludge reuse ranged from 10-4 to 10-2 while it was <10-14 to 10-1 for rotavirus infections
per single exposure. The treatment of faecal sludge significantly reduced the risk of rotavirus infections but
had less effect on the reduction of Ascaris infections. It is stressed that the estimated risks of infection need
to be validated against follow-up data obtained from epidemiological investigations coupled with studies
on different health risk barriers
On-site treated wastewater disposal systems – The role of stratified filter medias for reducing the risk of pollution
The transmission of pathogens from partially or fully treated wastewater to different water sources are a pervasive risk to public health. To reduce the risk, the integration of source separation, on-site greywater treatment system, and an efficient disposal scheme are the most critical approaches. This study intended to evaluate the removal of nutrient and microbial suspension in the filtration systems used for effluent disposal. The effluent from an on-site greywater treatment plant was loaded into the columns, and the effluent from the columns was monitored for nutrients, total coliform bacteria, Escherichia coli, and Salmonella typhimurium phage 28B (St28B) for one year. Thus, from the range of infiltration systems tested, column-B (15 cm layer of each, Filtralite, fine sand, and till soil) showed the highest removal of total coliforms and E. coli, 3–4 log10 reduction, while the lowest removal observed in column-C (a layer of 25 cm crushed stone and 50 cm till soil), 2–3 log10 reduction. The virus removal efficiency of the columns reduced from 19% to 70% during the simulation of a rainfall event. Moreover, the rise of St28B concentration after rainfall experiment may probably the sign of detachment enhanced by low ionic strength rainwater.publishedVersio
Treated greywater reuse for hydroponic lettuce production in a green wall system: Quantitative health risk assessment
publishedVersio
On-site treated wastewater disposal systems – The role of stratified filter medias for reducing the risk of pollution
The transmission of pathogens from partially or fully treated wastewater to different water sources are a pervasive risk to public health. To reduce the risk, the integration of source separation, on-site greywater treatment system, and an efficient disposal scheme are the most critical approaches. This study intended to evaluate the removal of nutrient and microbial suspension in the filtration systems used for effluent disposal. The effluent from an on-site greywater treatment plant was loaded into the columns, and the effluent from the columns was monitored for nutrients, total coliform bacteria, Escherichia coli, and Salmonella typhimurium phage 28B (St28B) for one year. Thus, from the range of infiltration systems tested, column-B (15 cm layer of each, Filtralite, fine sand, and till soil) showed the highest removal of total coliforms and E. coli, 3–4 log10 reduction, while the lowest removal observed in column-C (a layer of 25 cm crushed stone and 50 cm till soil), 2–3 log10 reduction. The virus removal efficiency of the columns reduced from 19% to 70% during the simulation of a rainfall event. Moreover, the rise of St28B concentration after rainfall experiment may probably the sign of detachment enhanced by low ionic strength rainwater
Nutrient Recovery from Anaerobically Treated Blackwater and Improving Its Effluent Quality through Microalgae Biomass Production
The blackwater stream of domestic wastewater contains energy and the majority of nutrients that can contribute to a circular economy. Hygienically safe and odor-free nutrient solution produced from anaerobically treated source-separated blackwater through an integrated post-treatment unit can be used as a source of liquid fertilizer. However, the high water content in the liquid fertilizer represents a storage or transportation challenge when utilized on agricultural areas, which are often situated far from the urban areas. Integration of microalgae into treated source-separated blackwater (BW) has been shown to effectively assimilate and recover phosphorus (P) and nitrogen (N) in the form of green biomass to be used as slow release biofertilizer and hence close the nutrient loop. With this objective, a lab-scale flat panel photobioreactor was used to cultivate Chlorella sorokiniana strain NIVA CHL 176 in a chemostat mode of operation. The growth of C. sorokiniana on treated source-separated blackwater as a substrate was monitored by measuring dry biomass concentration at a dilution rate of 1.38 d−1, temperature of 37 °C and pH of 7. The results indicate that the N and P recovery rates of C. sorokiniana were 99 mg N L−1d−1 and 8 mg P L−1d−1 for 10% treated BW and reached 213 mg N L−1d−1 and 35 mg P L−1d−1, respectively when using 20% treated BW as a substrate. The corresponding biomass yield on light, N and P on the 20% treated BW substrate were 0.37 g (mol photon)−1, 9.1 g g−1 and 54.1 g g−1, respectively, and up to 99% of N and P were removed from the blackwater.publishedVersio
On-site treated wastewater disposal systems – The role of stratified filter medias for reducing the risk of pollution
The transmission of pathogens from partially or fully treated wastewater to different water sources are a pervasive risk to public health. To reduce the risk, the integration of source separation, on-site greywater treatment system, and an efficient disposal scheme are the most critical approaches. This study intended to evaluate the removal of nutrient and microbial suspension in the filtration systems used for effluent disposal. The effluent from an on-site greywater treatment plant was loaded into the columns, and the effluent from the columns was monitored for nutrients, total coliform bacteria, Escherichia coli, and Salmonella typhimurium phage 28B (St28B) for one year. Thus, from the range of infiltration systems tested, column-B (15 cm layer of each, Filtralite, fine sand, and till soil) showed the highest removal of total coliforms and E. coli, 3–4 log10 reduction, while the lowest removal observed in column-C (a layer of 25 cm crushed stone and 50 cm till soil), 2–3 log10 reduction. The virus removal efficiency of the columns reduced from 19% to 70% during the simulation of a rainfall event. Moreover, the rise of St28B concentration after rainfall experiment may probably the sign of detachment enhanced by low ionic strength rainwater