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Full‐scale sampling at 16 facilities illustrated that NDMA precursor concentrations, measured by adding chloramine under Uniform Formation Conditions (NDMAUFC), increased across biofiltration at 7 of 16 facilities (by 3–48 ng/L or 12%–296%) but stayed the same or decreased (by up to 5 ng/L or 24%) at the other nine facilities. Increases in NDMAUFC concentrations were attributed to both particulate and soluble precursors. Only two facilities had an increase in NDMAUFC greater than 10 ng/L. However, NDMAUFC concentrations in the biofilter effluent from five facilities exceeded 10 ng/L during one or more sampling events. For these facilities, testing at multiple scales showed that mitigation steps could include pretreatment with ozone (which resulted in overall lower NDMAUFC), increased free chlorine contact time prior to ammonia addition, and/or optimized biofilter design and operation. [ABSTRACT FROM AUTHOR]

Alameda County Water District has observed increased biofilter effluent manganese concentrations during winter operations. To investigate manganese removal across surface water biofilters during cold‐water conditions, trends were analyzed between water temperature and manganese removal across multiple testing scales, multiple biofilter influent water qualities, and both anthracite and GAC media. During acclimation of new biofilters, 100% removal of manganese was observed sooner across both anthracite and GAC biofilters brought online at 20°C compared to 12°C. Acclimation at 12°C required 18 extra days for the GAC biofilters and 48 additional days for the anthracite biofilters. For fully acclimated biofilters, a decrease in manganese removal across both GAC and anthracite biofilters at temperatures below 15°C was observed. However, greater and more consistent manganese removal was observed across GAC compared to anthracite biofilters. Performance differences between locations also suggest that operational and water quality conditions also likely affect manganese removal. [ABSTRACT FROM AUTHOR]

The City of Denton, Texas, upgraded the Lake Lewisville Water Treatment Plant (WTP) to add ozone and convert the existing chlorinated anthracite/sand filters to granular activated carbon (GAC) biofilters. Biofilter contaminant removal, operational performance, and biomass were monitored following startup on two filters, one brought online in winter and one brought online in summer, to understand seasonal impacts. In addition, the city also monitored anthracite biofilters following a winter shutdown at another WTP. Key conclusions include (1) acclimation (i.e., the time required to achieve steady‐state biomass, total organic carbon [TOC] removal, or total manganese removal, considered individually) was two to three times longer for filters brought online in the winter versus the summer, (2) no acclimation period was observed for turbidity or total iron removal, and (3) the relationship between TOC removal and water temperature was more significant for the WTP with anthracite than GAC biofilters. [ABSTRACT FROM AUTHOR]

2D nanomaterials have long been considered for development of high permeability membranes. However, current processes have yet to yield a viable membrane for practical use due to the lack of scalability and substantial performance improvements over existing membranes. Herein, an ultrathin graphene oxide (GO) membrane with a permeability of 1562 mL h−1 mmHg−1 m−2, two orders of magnitude higher than the existing nanofiltration membranes, and a tight molecular weight cut‐off is presented. To build such a membrane, a new process involving self‐assembly and optimization of GO nanoplatelet physicochemical properties is developed. The process produces a highly organized mosaic of nanoplatelets enabling ultra‐high permeability and selectivity. An adjustable molecular interlinker between the layers enables absolute nanometer‐scale size cut‐offs. These characteristics promise significant improvements to many nanoparticle and biological separation applications. In this work, the performance of the membrane in blood dialysis scenarios is evaluated. Urea and cytochrome‐c sieving coefficients of 0.5 and 0.4 are achieved while retaining 99% of albumin. Hemolysis, complement activation, and coagulation studies exhibit a performance on par or superior to the existing dialysis membrane materials. [ABSTRACT FROM AUTHOR]

This work aims to develop a suitable aquaculture system to solve issues pertaining to water quality in recirculating aquaculture systems (RAS) thereby improving fish growth performance and their feed conversion ratio (FCR). It is known that the efficiency of nutrient decomposition depends on the amount and species of bacteria present in the filter, and these can in turn be regulated by the pH. Our study shows that the significant increase in pH from 7.45 to 7.51 and 7.47 is achieved after the water was filtered through sawdust and wood wool respectively. At the same time, nitrite concentrations were found to have significantly decreased from 0.06 ppm in the control to 0.01 ppm in the sawdust treatment. Changes in the physical–chemical properties of treated water affect the biological properties of the organisms. It was found that the average final body weight for fish in the wood wool treatment 30.96 g and fish in the sawdust treatment 31.44 g was significantly higher compared to that for the fish in the control treatment 28.42 g. The use of sponge, wood wool or sawdust resulted in significantly lower FCR and therefore better fish productivity in RAS. At the same time, the red blood cell count, plasma urea, plasma creatinine, plasma albumin, and GOT and GPT were significantly higher in fish in the plastic, sponge, wood wool or sawdust treatment compared to the control treatment. In summary, this study demonstrates the benefits of using sponge, wood, wool and sawdust as biofilter media for aquaculture. [ABSTRACT FROM AUTHOR]

Key Takeaways: Houston's Northeast Water Purification Plant expansion project is required to comply with subsidence district rules for conversion from groundwater to surface water supply. Innovative solutions for the expanded plant include two coagulation recipes to treat water from Lake Houston; treatment with chlorine dioxide, ozone, and biological filtration; and enhanced residuals treatment. A progressive design–build approach—used for the largest project of this kind presently underway in North America—maximized stakeholder involvement. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the biological filtration capabilities of some culinary herbs co‐cultured with lemon fin barb hybrid in a nutrient film technique (NFT) recirculating aquaponic system. Lemon fin barb hybrid (Hypsibarbus wetmorei ♂ × Barbonymus gonionotus ♀) fingerlings were stocked in twelve 2‐tonne fibreglass tanks at 25 fish per tank and co‐cultured with Chinese celery (Apium graveolens var. secalinum Alef.), coriander (Coriandrum sativum) and peppermint (Mentha × piperita) for seven weeks. The impacts of the waste generated by the fish on the water quality, the filtration capability of the herbs and the ability of fish and herbs to retain nutrients (NPK) were also estimated. All the herbs showed water purifying potentials to varying degrees as significantly lower levels of nitrogenous compounds (NH3‐N, NO3‐N, NO2‐N) were observed after the herbal filtration. The plant growth seemed to be affected by their ability to absorb nutrients and consequently purify the culture medium. Interestingly, the lemon fin barb hybrid also showed significant differences in terms of weight gain, but the nutrient retention among fish treatments was not statistically different. The plants absorbed less phosphorus and potassium than the fish. After computing for the total system percentage of NPK recovered, nitrogen was the most retained nutrient. The peppermint showed superiority in terms of gross biomass and water purifying potential compared to the Chinese celery and coriander. [ABSTRACT FROM AUTHOR]

Recirculating aquaculture systems (RASs) are intensive aquaculture facilities models that depend on diverse water treatment equipment to maintain good water quality and produce safe and healthy high‐quality aquatic products. This article combines the main farming‐mode of water purification recirculating processes with recent cultivation‐mode scientific research and the current development of the recirculating aquaculture industry. Harmful substances are present in aquaculture wastewater due to large quantities of residual particulate matter such as residual feed, faeces and small suspended solid particles, as well as ammonia, nitrite, bacteria and carbon dioxide (CO2), in the water. These harmful substances seriously affect the quality of aquatic products, so water treatment equipment is needed to remove these substances, add oxygen (O2) to the water and adjust the temperature of the water to ensure a high‐quality environment for fish survival. This article reviews the equipment for physical filtration (e.g. solid–liquid separation equipment, microscreen drum filter and foam fractionator) that could remove suspended solids during the water treatment of RASs and the equipment for biological filtration (e.g. fluidized sand biofilter (FSB), moving‐bed biofilm reactor (MBBR) and rotating biological contactor (RBC)) that could remove ammonia nitrogen, nitrite and other hazardous substances from wastewater, as well as equipment for water disinfection and sterilization, O2 addition, CO2 removal and temperature control. Comprehensive analysis and discussion of water treatment efficiency are provided for reference to create efficient high‐end recirculation aquaculture models and increase the precision and intelligence degree of recirculating water treatment technologies in the future. [ABSTRACT FROM AUTHOR]

Biofilters have gained in popularity for drinking water treatment for reasons that include reducing disinfectant demand, disinfection by-product formation, and regrowth in distribution systems. Adenosine triphosphate (ATP) detection is being used more frequently as an easy and rapid method to quantify viable biomass in biofilters; however, there is little information on the relationship of ATP levels to biofiltration parameters and performance. In this study, a comprehensive comparison of published ATP data was conducted, which found that concentrations at the top of active, acclimated biofilters typically were in the range of 102 to 103 ng ATP/cm3 media. The effect of various biofilter parameters (source water characteristics and quality, pretreatment, hydraulic loading rate, temperature, and sampling depth) on ATP levels is discussed and evaluated using published ATP data. The authors also assess the relationship between ATP and biofilter performance in terms of carbon removal and identify a need for further research in this area. [ABSTRACT FROM AUTHOR]

Removal of dissolved organic and inorganic contaminants is an anticipated benefit of the biofiltration of drinking water; however, common biofiltration design and operational practices do not seek to enhance the biological activities associated with those removals. A pilot-scale study identified two enhancement strategies-nutrient and peroxide dosing-that improved both water quality and hydraulic performance of a biofilter. These strategies control the formation of extracellular polymeric substances (a potential foulant of biological filters) while maintaining or increasing microbial activity. Biofilter nutrient enhancement was found to decrease terminal head loss by ∼ 15% relative to a control filter with no nutrient enhancement. Nutrient enhancement also sustainably decreased breakthrough of 2-methylisoborneol (MIB), manganese (Mn), and dissolved organic carbon (DOC). Peroxide enhancement was performed to increase oxidative action of biofilter microorganisms and promote the oxidation of inactive biomass. Peroxide enhancement decreased terminal head loss up to ∼ 60% relative to the control filter, while maintaining MIB, Mn, and DOC treatment performance. This case study is an important step in moving the practice of biofiltration from a passive process to a purposefully operated biological system, i.e., engineered biofiltration [ABSTRACT FROM AUTHOR]

The article discusses a study on the fate of saxitoxins in biologically active water treatment plant (WTP) filters. The saxitoxins, a group of potent alkaloid neurotoxins produced by cyanobacteria and dinoflagellates in freshwater and marine environments, block nerve cell sodium channels and can cause death if consumed in sufficient quantity. Findings revealed that decreases in the concentration of the less toxic variants coincided with increases in the concentrations of the more toxic variants through the filters containing anthracite sourced from two different WTPs. According to the study, organisms within the biofilm of the anthracite filters possessed the ability to biotransform the saxitoxins variants, which has important implications for the treatment of drinking water.

During the past 12 years, six small water treatment systems in Western Canada have used biological filtration as a pretreatment process for reverse osmosis membranes. INSET: EXPLORING PRETREATIVIENT OPTIONS IN YELLOW QUILL F. [ABSTRACT FROM AUTHOR]

Graphene Oxide Membranes: Trilayer Interlinked Graphene Oxide Membrane for Wearable Hemodialyzer (Adv. Keywords: biological filtration; graphene oxide; hemocompatibility; hemodialysis; membranes EN biological filtration graphene oxide hemocompatibility hemodialysis membranes 1 1 1 02/08/21 20210205 NES 210205 A new self-assembly process produces a highly organized mosaic of a few layers of graphene oxide nanoplatelets enabling membranes with ultra-high permeability and selectivity. In article number 2001985, Richard Rode, Saeed Moghaddam, and co-workers evaluate the membrane for hemodialysis, demonstrating two orders of magnitude improved permeability compared to typical polymer membranes. [Extracted from the article]

Continuous organic characterization at a full‐scale drinking water treatment plant was achieved using fluorescence spectroscopy. The feasibility of this method was demonstrated through monitoring the performance of biological activated carbon contactors (BACCs), which serve as pretreatment for fouling control of ultrafiltration (UF) membranes. Fluorescence monitoring was applied successfully to identify the preferential removal of select fluorescence components and addition of another microbial humic‐like component by the biological filters. Spikes in BACC influent organic matter and fouling development on the downstream UF membranes highlighted the importance of preozonation. To demonstrate possible use of the short‐term continuous fluorescence data, neural networks were used to predict fouling development on downstream UF on the basis of BACC effluent water quality. Short‐term fluctuations in fouling development were well predicted by incorporation of continuous fluorescence characterization data. Continuous organic characterization shows promise for the application of fluorescence spectroscopy for real‐time process optimization and control in drinking water treatment systems. [ABSTRACT FROM AUTHOR]

Biofiltration, a reliable process that has been used to purify water for hundreds of years, can address a wide array of regulated and emerging contaminants of concern. However, the water industry lacks a comprehensive set of best practices for biofiltration use. To address this knowledge gap, the Water Research Foundation (WRF) launched Project 4459, Development of a Biofiltration Knowledge Base (http://bit.ly/OsQUdy), to catalog information from high‐rate biofiltration facilities across North America. [ABSTRACT FROM AUTHOR]

Biological filtration, an important process step for the production of microbially safe and aesthetically pleasing drinking water, has attracted increased attention within the water industry. In many cases,the most economical way to implement biological rapid filtration is to achieve biodegradable organic matter (BOM) removal and particle removal within the same filter unit, i.e., single-stage biological filtration. This requires optimization of the filtration process, keepingin mind both treatment goals: BOM and particle removal. This articlepresents a critical review of the key parameters and engineering variables influencing the biological performance, as well as the conventional performance, of biologically active filters. Several areas requiring further research have been identified. [ABSTRACT FROM AUTHOR]