bluuebunny/crossref_metadata_2025_split huggingface dataset:
Air transfer efficiency of packed saturators used in DAF
Authors: Steinbach Sandra , Haarhoff Johannes 
Published: February 2018

A mathematical model predicts how saturation pressure, hydraulic loading, and packing depth affect air transfer.A rational model that predicts the air transfer efficiency in the packing layer of dissolved‐air flotation saturators is described. The model is defined in terms of absolute air concentrations, assumes the Lewis‐Whitman two‐film theory, and uses the Onda correlations to estimate the mass transfer coefficient. A comprehensive method is proposed for experimentally determining the overall air transfer efficiency of an operating saturator. A series of experiments was performed to partition the overall transfer efficiency into the contributions of top and bottom end effects, of free fall of the water before it reaches the packing, and of the packing itself. The laboratory data show a close agreement of the theoretical model with the measured performance. The model is used to demonstrate the effects of the most important saturator design parameters on the concentration of precipitable air.
Public affairs and the consumer landscape
Authors: Baron John M. 
Published: February 2018

Water utilities need to get into their customers' heads to win their hearts and minds.The water industry needs to develop a public information program that effectively publicizes its efforts to maintain a safe water supply. To do this, the industry needs to know the needs of its customers. Customers are motivated by concerns about health, good value for price, service, and the environment. As groups they may lobby for federal protection when the need is felt, and as individuals they may simply switch their allegiance to bottled water. Although they are overloaded with information, they remain interested in information relating to personal and public health. The industry needs to give customers information that meets their substantive and emotional needs. Asking them is the best way to determine what this information is.
Backwashing first‐stage sand–BAC filters
Authors: Niquette Patrick , Prévost Michèle , Maclean Robert G. , Thibault Daniel , Coallier Josée , Desjardins Raymond , Lafrance Pierre 
Published: February 2018

Does it increase removal of biodegradable organic matter and ammonia?The effect of filter backwash on the efficiency of first‐stage sand–biological activated carbon (BAC) filters was evaluated by comparing, in first‐stage sand–BAC filters, concentrations of ammonia, biodegradable dissolved organic carbon, aldehydes, and oxalate. These concentrations were measured before and after filter backwash. Filter position (first‐stage sand–BAC filters versus second‐stage BAC filters) was also studied to understand how flocs and particle accumulation influenced the efficiency of the first‐stage sand–BAC filter. A first‐stage sand–anthracite filter operated under similar hydraulic conditions and effluent turbidity acted as a reference. Filter backwash improved the efficiency of sand–BAC filters, especially in cold water sources. However, both filters produced similar water quality. First‐stage sand–anthracite filters did not adequately remove biodegradable organic matter and ammonia.
Energy management opportunities
Authors: Arora Harish , LeChevallier Mark W. 
Published: February 2018

Annual savings attributable to management of electric demand were estimated at $3.4 million.Energy costs are a major part of total operation and maintenance expenses for a water utility. An energy survey of the American Water System (AWS) water companies was conducted, and energy audits were conducted at three representative AWS water supply systems. The audits identified energy savings ranging from 10 to 32 percent compared with 1993 electrical costs. Cost‐effective energy conservation measures consisted of base loading the most efficient plant in a multiplant water system, implementing strategies to reduce demand charges, modifying pumps, and installing energy‐efficient lighting. Installation of variable‐frequency drives, standby generators, and energy‐efficient motors was recommended, but these devices were not cost‐effective. Energy savings and the corresponding implementation costs were extrapolated for the entire AWS on the basis of the surveys and results of the three audits. Identified energy conservation measures may save AWS $3.4 million annually (12.3 percent of existing energy costs) at an implementation cost of $6.1 million, with a payback period of 1.8 years.
Controlling DBPs with monocholoramine
Authors: Carlson Mark , Hardy Douglas 
Published: February 2018

Operators can adjust pH, contact time, and chlorine dosage to promote disinfection while retarding formation of disinfection by‐products.Balancing disinfection with control of disinfection by‐products (DBPs) requires an understanding of how common water quality variables such as chlorine dosage and contact time, temperature, pH, and total organic carbon (TOC) affect both processes. This article examines how these variables affect the concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs) at the shorter contact times associated with the use of chloramines, rather than chlorine, for residual disinfection. Five case studies evaluated DBPs in five water sources of differing quality. The most important variables were TOC and chlorine contact time, but chlorine dosage, pH, and temperature also had an effect. Response to some variables was linear; response to others was nonlinear. In most water sources, THM concentrations were greater than HAA concentrations, but in some the reverse was true. DBP concentrations must be investigated under a range of conditions to determine the best way to use chlorine disinfection while minimizing concentrations of DBPs.
Working with the USDA to protect source water
Authors: Pedersen Dan W. , Luitweiler J. Preston , Torobin Marcia 
Published: February 2018

Federal agricultural conservation programs can support the protection of drinking water sources.In the past, water suppliers often relied on pristine sources of water from distant locales. With rapid population growth and the advent of intensive land use, however, water suppliers can no longer ignore the quality of their source water. The 1996 Safe Drinking Water Act amendments recognized this and authorized voluntary state‐supported incentive‐based petition programs, through which water suppliers can work with landowners and local organizations to protect source water. In addition to good‐faith efforts, financial incentives will be helpful in assuring an effective petition program. This article describes US Department of Agriculture incentive programs and how water suppliers can participate in them to augment their source water protection efforts.
Water conservation guidelines and the DWSRF
Authors: Beecher Janice A. , Flowers John E. , Matzke Charles S. 
Published: February 2018

The SDWA's conservation guidelines provision reverberates throughout the DWSRF to help encourage conservation measures.The Safe Drinking Water Act amendments of 1996 include a short and relatively little known provision concerning water conservation planning. The provision requires the US Environmental Protection Agency to publish guidelines for conservation planning by water systems. However, use of the guidelines in conjunction with the Drinking Water State Revolving Fund (DWSRF) or other programs is completely at the discretion of the states. For example, states can choose whether to require a conservation plan as part of a DWSRF application or award points to systems based on their completion of a plan. Although conservation planning is a voluntary provision, it has the potential to bring conservation into the mainstream of utility capital planning. Strategic use of conservation will help extend the value and life of water supply assets, while also expanding the beneficial investment of public funds through the DWSRF.
UV light inactivation of Cryptosporidium oocysts
Authors: Clancy Jennifer L. , Hargy Thomas M. , Marshall Marilyn M. , Dyksen John E. 
Published: February 2018

Animal infectivity studies demonstrate the efficacy of pulsed and advanced UV in inactivating Cryptosporidium oocysts.Cryptosporidium parvum oocysts are highly resistant to conventional chlorine‐based disinfectants. The authors tested two innovative electrotechnologies that use ultraviolet (UV) light and found that both pulsed UV and advanced UV inactivated Cryptosporidium oocysts. The advanced UV system achieved >4‐log inactivation as determined in animal infectivity studies using the neonatal mouse model. With the pulsed UV system, oocyst inactivation was also noted in the process control (non‐UV‐exposed oocysts), suggesting that some oocyst inactivation may have occurred independently of UV exposure. Irrespective of this, both technologies appear to be effective and novel ways to treat drinking water and to provide an additional significant barrier that helps protect public health.
Rejection of MS‐2 virus by RO membranes
Authors: Adham Samer S. , Trussell R. Shane , Gagliardo Paul F. , Trussell R. Rhodes 
Published: February 2018

If reverse osmosis is to be used for pathogen removal, quality control measures are necessary.A bench‐scale study was conducted to evaluate MS‐2 virus rejection by reverse osmosis membranes. Viruses were recovered in permeate passing through some of the membrane structures. Thus, if reverse osmosis is to be used for pathogen removal, quality control measures on reverse osmosis membrane manufacturing are necessary to ensure that the required level of removals are achieved consistently.
Maryland program builds operator skills
Authors: Barrett Joy M. 
Published: February 2018

Innovative training center combines peer‐to‐peer instruction and technical assistance to hone trainees' know‐how.For 15 years, the Maryland Center for Environmental Training (MCET) has been dedicated to training operators to deliver safe drinking water to local communities. The state of Maryland has been a national leader in the operator certification movement and has developed a rigorous program for building operators' technical skills and ensuring appropriate qualification of all operators working in the state. MCET's training and technical assistance programs are based on solid principles, including peer‐to‐peer training, building local expertise, and developing and distributing effective publications and training curricula.
ICR treatment studies
Authors: Allgeier Steven C. , Shukairy Hiba M. , Westrick James J. 
Published: February 2018

Utilities are currently evaluating membranes and GAC for DBP precursor removal.Under the treatment study requirement of the Information Collection Rule, 493 treatment plants were required to monitor total organic carbon (TOC) concentrations in their influent or finished water to determine whether studies evaluating granular activated carbon or membranes would be required. These TOC results were aggregated and analyzed by source water type, treatment type, disinfection practices, and geographic location. Seventy‐eight percent of these plants met the criteria to avoid the treatment study requirement. The remaining plants will be required to conduct new treatment studies, submit data from previous studies, or contribute funds to a cooperative research effort. Under the treatment study requirement, 62 granular activated carbon studies and 37 membranes studies will be conducted.
Using a membrane bioreactor to reclaim wastewater
Authors: Cicek Nazim , Franco Juan P. , Suidan Makram T. , Urbain Vincent 
Published: February 2018

The membrane bioreactor is an emerging technology for the reclamation of municipal wastewater.A pilot‐scale membrane bioreactor sufficiently purified simulated municipal wastewater for indirect recharge to groundwater or nonpotable uses. Throughout more than 500 days of steady‐state operation, total organic carbon concentrations of <1.1 mg/L and chemical oxygen demand of <3.5 mg/L were consistently achieved. No suspended solids were detected in the effluent during this period. The treated water was fully nitrified, resulting in low ammonia and organic nitrogen concentrations but high nitrate concentrations. Cyclic oxic–anoxic operation or an additional denitrification process would be necessary to meet potable water reuse standards. Phosphorus was fully used in the bioreactor for biological growth. Heterotrophic bacteria and MS‐2 viruses were completely retained by the membrane system, reducing the extent of final disinfection required.
Distributing groundwater without a disinfectant residual
Authors: Hambsch Beate 
Published: February 2018

In Germany, high‐quality groundwater may be distributed without a disinfectant residual.Microbiological data on drinking water in a distribution system were compared before and after the treatment plant discontinued use of a chlorine residual. Bacteriological assessments of chlorinated groundwater consistently showed heterotrophic plate counts (HPCs) < 5 colony forming units (cfu)/mL, a count indicating that bacterial regrowth was very unlikely. Because chlorination that produced about 0.1 mg/L free chlorine residual led to taste and odor complaints, chlorination was discontinued, and water that contained no residual was distributed. Shortly after this change, samples with higher retention times produced HPCs as high as 60–80 cfu/mL. After four to six weeks these counts decreased to values again < 5 cfu/mL. This short‐term increase in HPCs, which has also been observed in other cases, is assumed to be due to a change in the biofilm.
Nitrate removal from contaminated groundwater
Authors: Liang Sun , Mann Mary Ann , Guter Gerald A. , Kim Philip H.‐S. , Hardan David L. 
Published: February 2018

An innovative approach to design of an ion exchange plant used data from bench‐scale tests and computer models.Data from bench‐scale tests were used in conjunction with computer model simulations to develop design criteria for an ion exchange treatment process for removing nitrate. This approach is a potentially economical means of predicting nitrate breakthrough profiles, which can be used to make preliminary assessments of nitrate operating capacity, as well as the effects of changing process parameters, on the operational efficiency of various ion exchange processes. In addition, the effects of volatile organic chemicals, strong oxidants such as chlorine, and arsenic adsorption on ion exchange resin degradation were assessed.
Medium‐pressure UV for oocyst inactivation
Authors: Bukhari Zia , Hargy Thomas M. , Bolton James R. , Dussert Bertrand , Clancy Jennifer L. 
Published: February 2018

In vivo studies indicate the infectivity of treated Cryptosporidium parvum oocysts more reliably than do in vitro assays.Inactivation of Cryptosporidium parvum oocysts in finished drinking water by medium‐pressure ultraviolet (UV) light was investigated at bench scale using a collimated beam apparatus and at demonstration scale using a UV reactor. Oocyst viability was assessed in vitro (using 4',6‐diamidino‐2‐phenylindole with propidium iodide and maximized in vitro excystation) and in vivo (using neonatal mouse infectivity assays). In vivo bench‐scale studies showed > 4‐log inactivation at UV dosages as low as 41 mJ cm–2, although in vitro surrogate assays showed little or no inactivation at this or higher UV dosages. The in vitro assays, which indicate oocyst viability, grossly overestimated the UV dosages required to prevent oocyst infection in susceptible hosts. Results of demonstration studies, carried out under the Environmental Technology Verification program of the National Sanitation Foundation and the US Environmental Protection Agency, agreed with the bench‐scale results and showed that a UV dosage as low as 19 mJ cm–2 provided 3.9‐log inactivation of Cryptosporidium oocysts.
Financial help for utilities along the US–Mexico border
Authors: Brackbill Craig E. 
Published: February 2018

Two interrelated international institutions offer much‐needed financial and technical assistance for communities along the US–Mexico border.With the economic growth spurred by passage of the North American Free Trade Agreement, the significant environmental infrastructure needs along the US–Mexico border were expected to become more severe. In 1993, the United States and Mexico addressed this concern, signing a bilateral agreement that created two new interrelated international institutions. The Border Environment Cooperation Commission (BECC) reviews and certifies environmental infrastructure projects proposed within 100 km (62 mi) of the international border. The North American Development Bank (NADBank) helps develop financing for BECC‐certified projects and also serves as a lender. To date, 26 projects have been certified, with 14 projects receiving direct NADBank funding. The institutions work with both public and private project sponsors and financial participants. Small systems are eligible both for grants to assist with the application process and for programs to develop their internal capacities for construction and operation of new facilities.
Predicting full‐scale TOC removal
Authors: Tseng Tai , Edwards Marc 
Published: February 2018

A Langmuir model providing good prediction of full‐scale TOC removal during enhanced coagulation may help utilities comply with forthcoming regulations.A Langmuir model provides the best available prediction of full‐scale removal of total organic carbon (TOC) during enhanced coagulation. Because jar tests allow more transfer of carbon dioxide gas than treatment plants, the model can even correct certain errors arising during such tests. When the model was adapted to predicting TOC removal in two raw water sources mixed together in different proportions, standard error was only 0.15 mg/L for two years of jar‐test data at one utility. Case studies of 27 full‐scale utilities showed accurate prediction of TOC removal by coagulation (1) at a range of utilities using alum, ferric, or polyaluminum chloride coagulants; (2) over long time periods without a need for frequent recalibration; (3) with use of a predicted rather than measured coagulation pH; and (4) for two raw water sources mixed in various proportions.
Selecting MF to satisfy regulations
Authors: Kelley William A. , Olson Roger A. 
Published: February 2018

When Marquette, Mich., was faced with having to filter its cold, clean source water for the first time, microfiltration was the technology of choice.The city of Marquette, Mich., operates a public water system that uses Lake Superior as its raw water source. Historically, only chlorination was provided so that the drinking water met state and federal drinking water standards. In 1989, the US Environmental Protection Agency promulgated the Surface Water Treatment Rule (SWTR), which requires filtration of all surface water sources unless the water supplier controls the watershed. This rule intensified efforts by the state's drinking water program to have the city install and operate a filtration system. The city was advised to construct a direct filtration plant but decided against it. An alternative suggestion for the city's cold, clean source water was microfiltration (MF). Results of a feasibility study and a pilot study were positive, and the city designed, constructed, and began operation of a 0.026 ˇ 106–m3/d (7‐mgd) MF plant. The plant, which has been on line for more than a year, has solved the SWTR regulatory concern and now provides the city with its drinking water.
NF performance at full and pilot scale
Authors: Mulford Luke A. , Taylor James S. , Nickerson David M. , Chen Shaio‐Shing 
Published: February 2018

Nanofiltration pilot plants accurately represented full‐scale plant performance.Productivity and water quality from the Roy W. Likens membrane facility in Palm Coast, Fla., were accurately simulated by three membrane pilot plants in a four‐month field investigation using various sizes of a film membrane manufactured by the same company and operated under the same conditions. All plants used the same source water, groundwater that is moderately hard (330 mg/L as CaCO3) and highly organic (11 mg/L non‐purgeable dissolved organic carbon, 336 trihalomethane formation potential [THMFP], 227 μg/L haloacetic acid formation potential [HAAFP]). All pilot units were built and operated according to standards in the Information Collection Rule (ICR). The average finished water quality for all membrane plants was 0.4 mg/L total organic carbon as C, 35 μg/L THMFP, and 28 HAAFP. For the full‐scale plant, membrane productivity decreased by 50 percent during five years. A second‐order resistance model more accurately described productivity over time than did a zero‐order direct mass transfer model, although both models produced statistically significant results. These results demonstrated that full‐scale plant performance could be accurately scaled up from single‐element or multistage pilot plants as specified in the ICR protocol.
Microfiltration goes Hollywood: the Los Angeles experience
Authors: Karimi Ali A. , Vickers James C. , Harasick Richard F. 
Published: February 2018

Finished water turbidity and particle removal were independent of flux.Faced with the need for additional treatment of its finished water stored in the Hollywood Reservoirs, the Los Angeles Department of Water and Power evaluated the efficacy of microfiltration (MF) to meet the requirements of the Surface Water Treatment Rule. This evaluation included a pilot test to assess the MF process and to define the design parameters (flux and frequency of chemical cleaning). Finished water turbidity and particle removal were independent of flux in the tested water. This finding allows the utility to operate the MF system at a flux as much as 50 percent higher than the 67‐gfd (114‐L/m2/h) flux currently allowed by California regulations. Membrane resistance was used to evaluate the system performance under variable operating conditions of temperature, flux, and pressure. A design flux of 67 gfd (114 L/m2/h) was projected to yield more than two months (i.e., 66 days) of filter run before chemical cleaning. A higher flux of 80–100 gfd (136–170 L/m2/h) was acceptable with more frequent chemical cleaning of the MF membranes.
Using limited data to assess future needs
Authors: Kleiner Yehuda , Rajani Balvant 
Published: February 2018

A five‐step methodology was developed to help utilities with sketchy or scarce data on water main break history to budget for future pipe replacement.Most major urban utilities are aware of the need to keep records of distribution system water mains. These records—which typically include data about water main break history, pipe material, pipe vintage, and soil type—are eventually used to allocate budgets to replace, rehabilitate, or repair aging distribution systems. Many utilities have incomplete or scarce water main data, which may make financial planning difficult. Thus, a methodology that facilitates the use of scarce, available data to assess future needs is warranted. Presented is a case study that followed five essential steps: (1) bundle data on water main breaks into homogeneous groups to predict future breaks for water utility regions for which data were insufficient, (2) establish breakage rate patterns for these groups to project future breakage rates, (3) use projected breakage rates to determine the economic life of water mains, (4) examine probabilistic scenarios of water main life, and (5) determine the investments required to replace water mains.