Log Removal Research Articles

Multiple benefits of MBR and absolute-rated cartridge filters for RO pretreatment: results from a full-scale facility

ABSTRACT There is interest in treatment processes that can both contribute to pathogen removal and provide effective pretreatment for reverse osmosis (RO) in potable reuse systems. The most familiar reuse treatment train employs micro-/ultrafiltration along with cartridge filters (CFs) upstream of RO. However, there are some applications for which other pre-RO treatment processes, such as membrane bioreactors (MBRs), are desirable. In such cases, more research is needed on MBR as an RO pretreatment process. In addition, although CFs are widely used, the literature does not elucidate their capability for pathogen removal and fouling control. In this study, an MBR process along with an absolute-rated 1 μm CF system was demonstrated for RO pretreatment at the full scale. Online MBR and CF data confirmed performance within critical control point limits, and breach testing of the CFs demonstrated a consistent response pattern in differential pressure data. These findings supported the first pathogen log removal credit for both MBR and CFs in California. The combined pretreatment processes also achieved remarkably low fouling rates at the downstream RO system, lower than other recently reported MBR-RO facilities and consistent with 5–7-month clean-in-place intervals. These results demonstrated the multiple benefits of a novel MBR-CF pre-RO treatment train.

Water Reuse—Retrospective Study on Sustainable Future Prospects

In recent decades, societies and economies across the globe have started to show signs of stress associated with water shortages. Meeting the sustainability benchmarks in arid and semi-arid regions has caused water reuse to be considered a viable alternate source to augment the existing water supply resources. Water reuse, resource recovery, and recycling are extensions of the concept of a circular economy that has been practiced in other fields. Globally, the U.S. has played a leadership role in the development of guidance and regulations for various water reuse applications. Other countries and organizations have also developed similar programs. This paper aims to propose a review of the existing literature and provide a broader perspective of water reuse focusing on the most pressing issues such as direct potable reuse with the backdrop of viral pathogens and perfluorinated compounds. The global history of statutory developments to regulate the selected contaminants has also been discussed by covering the recent advancement in water reuse applications. Technological developments and regulatory trends are chronicled in the context of emerging contaminants linked with an imminent social, industrial, and agricultural prospectus. The proposed high viral log removal credit for water reuse is a challenging task especially at regular intervals; therefore, the treatment requirements must be verified to ensure public safety. The extreme persistence of PFAS, their tendency for buildup in biotic systems, and their removal is another challenging task which requires development of cost effective and efficient technologies. Disparity in the financial and technological capabilities of regional or internal stakeholders of shared watershed or aquifer is a bottleneck in tangible advancements in this area. The role of public–private partnerships in addressing the impending water sustainability challenges is discussed as a model for future direction in funding, managing, and public acceptance.

Towards stormwater reuse risk management plans: Methodology and catchment scale evaluation of QMRA.

Towards stormwater reuse risk management plans: Methodology and catchment scale evaluation of QMRA.

Influence of substrate particle size and detention time on mycelium-colonized sawdust efficiency for removal of faecal bacteria from slaughterhouse wastewater in batch treatment

Mycofiltration is a recent cost-effective biotechnology that is still under development for wastewater treatment. The use of mycelium-colonised substrate for wastewater treatment in a batch system with delayed residence time and the effect of sawdust particles has not previously been considered. Slaughterhouse wastewater is discharged untreated in many developing countries majorly due to the high cost of existing conventional treatment systems. The effect of sawdust detention time and particle size on the removal efficiency of faecal bacteria from slaughterhouse wastewater by Pleurotus ostreatus mycelium was assessed in the lab using mycelium colonized with sawdust of particle sizes (0.6, 1.18, 2.36 mm and unsorted particle sizes) and under varying detention times (0, 12, 24, 36, 48, 60 and 72 hours) using batch treatment procedure. Hydrogen peroxide produced during mycelium colonisation of the sawdust was also evaluated. Oxidation-reduction potential (ORP) was measured during this study to determine the oxidative capacity in each treatment reactor. The removal efficiency of Escherichia coli ranged from -7.9 – 77.2 % and was the highest for mycofilter with 2.36 mm sawdust particle size at 72 hours detention time (0.7 log removal). Salmonella spp. removal efficiency ranged from 0.66 – 71 % with the highest efficiency recorded in the system with 1.16 mm also at 72 hours (0.4 log removal). Mean hydrogen peroxide concentration ranged from 0.53±0.12 (unsorted inoculated) to 25.18±1.77 mg/l (1.18 mm, 72 hours). ORP values ranged from 5.0±2.2 mV (raw wastewater, 24 hours) to 232±55 mV (unsorted inoculated, 72 hours). The result of this study showed that substrate particle size and detention time have roles to play in the efficiency of mycofilters using batch treatment. The concentration of hydrogen peroxide was also influenced significantly by sawdust particle size. Therefore, there is a need to further study this system in a bid to optimize its ability to remove faecal bacteria from wastewater.

Local Electric Field-Incorporated In-Situ Copper Ions Eliminating Pathogens and Antibiotic Resistance Genes in Drinking Water.

Pathogen inactivation and harmful gene destruction from water just before drinking is the last line of defense to protect people from waterborne diseases. However, commonly used disinfection methods, such as chlorination, ultraviolet irradiation, and membrane filtration, experience several challenges such as continuous chemical dosing, the spread of antibiotic resistance genes (ARGs), and intensive energy consumption. Here, we perform a simultaneous elimination of pathogens and ARGs in drinking water using local electric fields and in-situ generated trace copper ions (LEF-Cu) without external chemical dosing. A 100-μm thin copper wire placed in the center of a household water pipe can generate local electric fields and trace copper ions near its surface after an external low voltage is applied. The local electric field rapidly damages the outer structure of microorganisms through electroporation, and the trace copper ions can effectively permeate the electroporated microorganisms, successfully damaging their nucleic acids. The LEF-Cu disinfection system achieved complete inactivation (>6 log removal) of Escherichia coli O157:H7, Pseudomonas aeruginosa PAO1, and bacteriophage MS2 in drinking water at 2 V for 2 min, with low energy consumption (10-2 kWh/m3). Meanwhile, the system effectively damages both intracellular (0.54~0.64 log) and extracellular (0.5~1.09 log) ARGs and blocks horizontal gene transfer. LEF-Cu disinfection holds promise for preventing horizontal gene transfer and providing safe drinking water for household applications.

Municipal secondary-treated effluent data seem to be a suitable source of information for human viral trends

Municipal secondary-treated effluent data seem to be a suitable source of information for human viral trends

Efficacy of Disinfectants for Monkeypox Virus Inactivation on High Touch Surface Materials in Low-Resource Settings.

Disinfection efficacy tests were conducted on surface carriers inoculated with the monkeypox virus (MPXV) by applying six disinfectant solutions (and three controls) on six surfaces common in low-resource settings: four nonporous surfaces (stainless steel, glass, plastic, and latex) and two porous surfaces (ceramic and wood). Disinfectants were wiped on carriers in triplicate, with a 1 min contact time: 0.05 and 0.5% sodium hypochlorite, 70% ethanol, two quaternary ammonium compound (QAC)-based disinfectants, and 1.4% hydrogen peroxide. MPXV was then quantified, and log10 removal values were calculated. Sodium hypochlorite (0.05 and 0.5%) and ethanol (70%) removed MPXV to below detection level, ≥ 99.97% reduction for nonporous surfaces, and ≥99.40% for wood, QAC-based disinfectants were efficacious on nonporous surfaces (≥99.97% inactivation) but had diminished efficacy on wood, a porous surface, and 1.4% H2O2 had limited efficacy across all tested surfaces. Results varied by disinfectant type and surface type. Based on our results, we recommend using 0.05% sodium hypochlorite or 70% ethanol with 1 min contact time to inactive MPXV on clean nonporous and porous surfaces. As MPXV is evolving, future research with additional disinfectants, application methods, and environmental conditions and research to understand adsorption, disinfection efficacy, and transmission risk on porous surfaces are needed to develop practical disinfection recommendations.

Efficient removal of organic matter and nitrogen from municipal wastewater in multi-module biochar filters for onsite wastewater treatment

ABSTRACT Biochar is a promising material for wastewater treatment. This study assessed multi-module biochar filters (MmBFs) as onsite wastewater treatment systems (OWTSs), comprising movable modules filled with biochar to remove chemical oxygen demand (COD), nitrogen, phosphorus, and Escherichia coli (E. coli) in wastewater. The MmBF treats wastewater sequentially through six modules: three aerobic modules (M1-M3) for organic matter oxidation and nitrification, two anoxic modules (M4-M5) for denitrification, and an additional module (M6) for the removal of faecal bacteria using biochar and bark. The experiments ran for 381 days using three identical MmBF pilots with two distinct sampling periods, conducted under conditions relevant to OWTSs using municipal wastewater as influent. Water samples were taken from the influent, final effluent, and effluent of each module to evaluate the removal efficiency of organic matter, nitrogen, phosphorus, and E. coli. During the second sampling period, the results showed a 95 ± 2.1% removal of COD, along with a substantial removal of total inorganic nitrogen (71 ± 6.6%). However, phosphate removal was limited (3.4 ± 30.4%). E. coli removal decreased from 2.63 ± 0.93 log10 removal in the first sampling period to 1.8 ± 0.73 log10 removal in the second sampling period. In summary, the MmBFs showed promising potential in treating organic matter, nitrogen, and E. coli, making it an alternative option for OWTS. However, further exploration is needed to assess long-term performance, micropollutant removal, and biological activities. Design enhancements, especially for phosphorus removal are necessary.

Electrochemical flow-through disinfection of Escherichia coli versus Staphylococcus aureus: Identifying impacts of flow patterns on efficiency

Electrochemical flow-through disinfection of Escherichia coli versus Staphylococcus aureus: Identifying impacts of flow patterns on efficiency

Bacteria and Cyanobacteria Inactivation Using UV-C, UV-C/H2O2, and Solar/H2O2 Processes: A Comparative Study

Effective disinfection processes have been investigated to provide pathogen-free drinking water. Due to growing concern about the potential negative effects of cyanobacteria in portable water, their treatment has gained more attention recently. This study aims to compare the inhibition efficiencies of Gram-negative bacteria (Escherichia coli; E. coli), Gram-positive bacteria (Bacillus subtilis; B. subtilis), and cyanobacteria (Microcystis aeruginosa; M. aeruginosa) using UV-C and solar irradiation, and their combination process with H2O2. Over 6 log removal value (LRV) of E. coli and B. subtilis was achieved within 1 min of UV-C irradiation (0.76 ± 0.02 mW/cm2). The solar and solar/H2O2 (50 mg/L) processes effectively reduced (>99%) both bacteria after 20 min. E. coli was more sensitive to hydroxyl radicals (•OH) compared to the B. subtilis due to a different cell wall structure, resulting in a 0.18–0.62 higher LRV than B. subtilis. However, solar-based processes did not effectively inhibit M. aeruginosa (>52.23%). The UV-C/H2O2 (50 mg/L) process showed the highest inhibition rate for M. aeruginosa (77.83%) due to the generation of •OH, leading to oxidative damage to cells. Additionally, chlorophyll-a (Chl-a) was measured to indicate cell lysis of M. aeruginosa. The removal rate of Chl-a extracted by viable M. aeruginosa was higher using the UV-C process (93.03%) rather than the UV-C/H2O2 process (80.95%), because UV-C irradiation could be most effective in damaging Chl-a.

Safeguarding reverse osmosis membrane integrity in drinking water production: A pilot study using 2 native bacterial communities and viruses in surface water as integrity indicators

Safeguarding reverse osmosis membrane integrity in drinking water production: A pilot study using 2 native bacterial communities and viruses in surface water as integrity indicators

Electrochemical removal of antibiotics and multi-drug resistant bacteria using S-functionalized graphene sponge electrodes

Electrochemical removal of antibiotics and multi-drug resistant bacteria using S-functionalized graphene sponge electrodes

Enhanced electrochemical disinfection for decentralized sewage treatment through nickel foam cathode modified with CoFe2O4-spinel ferrite and multi-way carbon nanotubes

Enhanced electrochemical disinfection for decentralized sewage treatment through nickel foam cathode modified with CoFe2O4-spinel ferrite and multi-way carbon nanotubes

Disinfection-residual bacteria (DRB) after chlorine dioxide treatment: Microbial community structure, regrowth potential, and secretion characteristics

Disinfection-residual bacteria (DRB) after chlorine dioxide treatment: Microbial community structure, regrowth potential, and secretion characteristics

Indicator and pathogenic virus removal in bench scale soil aquifer treatment

Indicator and pathogenic virus removal in bench scale soil aquifer treatment

Treatment of pharmaceutical industry wastewater for water reuse in Jordan using hybrid constructed wetlands

Developing cost-efficient wastewater treatment technologies for safe reuse is essential, especially in developing countries simultaneously facing water scarcity. This study developed and evaluated a hybrid constructed wetlands (CWs) approach, incorporating tidal flow (TF) operation and utilising local Jordanian zeolite as a wetland substrate for real pharmaceutical industry wastewater treatment. Over 273 days of continuous monitoring, the results revealed that the first-stage TFCWs filled with either raw or modified zeolite performed significantly higher reductions in Chemical Oxygen Demand (COD, 58 %–60 %), Total Nitrogen (TN, 32 %–37 %), and Phosphate (PO4, 46 %–64 %) compared to TFCWs filled with normal sand. Water quality further improved after the second stage of horizontal subsurface flow CWs treatment, achieving log removals of 1.09–2.47 for total coliform and 1.89–2.09 for E. coli. With influent pharmaceutical concentrations ranging from 275 to 2000 μg/L, the zeolite-filled hybrid CWs achieved complete removal (>98 %) for ciprofloxacin, ofloxacin, erythromycin, and enrofloxacin, moderate removal (43 %–81 %) for flumequine and lincomycin, and limited removal (<8 %) for carbamazepine and diclofenac. The overall accumulation of pharmaceuticals in plant tissue and substrate adsorption accounted for only 2.3 % and 4.3 %, respectively, of the total mass removal. Biodegradation of these pharmaceuticals (up to 61 %) through microbial-mediated processes or within plant tissues was identified as the key removal pathway. For both conventional pollutants and pharmaceuticals, modified zeolite wetland media could only slightly enhance treatment without a significant difference between the two treatment groups. The final effluent from all hybrid CWs complied with Jordanian treated industry wastewater reuse standards (category III), and systems filled with raw or modified zeolite achieved over 95 % of samples meeting the highest water reuse category I. This study provides evidence of using hybrid CWs technology as a nature-based solution to address water safety and scarcity challenges.

High-density Co-Nx sites anchored on biomass-based carbon nanotubes for efficient removal of plant viruses in water

High-density Co-Nx sites anchored on biomass-based carbon nanotubes for efficient removal of plant viruses in water

Virus removal by microfiltration: Effects of electrostatic and hydrophobic interactions

Virus removal by microfiltration: Effects of electrostatic and hydrophobic interactions

Activated carbon amendment of sand in the base of a permeable pavement reduces total nitrogen and nitrate leaching

Activated carbon amendment of sand in the base of a permeable pavement reduces total nitrogen and nitrate leaching

Rational design of a hydrophilic nanoarray-structured electro-Fenton membrane for antibiotics removal and fouling mitigation: An intensified catalysis process in an oxygen vacancy‐mediated cathodic microreactor

Rational design of a hydrophilic nanoarray-structured electro-Fenton membrane for antibiotics removal and fouling mitigation: An intensified catalysis process in an oxygen vacancy‐mediated cathodic microreactor