Professionalized maintenance arrangements are growing throughout sub-Saharan Africa to improve rural water infrastructure functionality after decades of largely unsuccessful community-based management (CBM), but factors influencing their success are understudied. We used a multimethod approach to (1) identify influential factors on rural water system reliability and sustainability in the literature; (2) determine the most influential factors for professionalized maintenance through focus group discussions with a Ugandan maintenance provider's technicians and field staff; and (3) identify statistically significant associations between these factors and breakdowns, downtime, and community maintenance contract status. Findings show that contract status, indicating consumer demand and payment, is influenced by service reliability, free repairs from NGOs, and the number of users. Handpump breakdowns are most likely during rainy seasons, when total downtime is longer for increasing distance from the maintenance provider's nearest office, likely due to travel challenges. Based on compelling quantitative and qualitative evidence, we call for increased coordination among key actors for more successful professionalized maintenance provision. For example, aid actors such as NGOs must respect formal professionalized arrangements in the contexts where they work. Additionally, maintenance providers and their funders must ensure adequate resource availability to overcome travel challenges and ensure equitable service provision.
After a critical review of the fundamental equations describing photobiological and photochemical processes occurring in a medium exposed to a quasi-collimated monochromatic UV light beam, the analysis in this review is extended to analogous processes driven by polychromatic UV light, such as that emitted by medium pressure mercury-vapor arc lamps. The analysis is based on the Second Law of Photochemistry, namely that all photochemical events must be independent, and the rate of such events must be proportional to the rate of photon absorption. A consistent application of the Second Law of Photochemistry leads to a concept change; hence it is proposed herein to use photon fluence and photon fluence rate, rather than fluence (UV dose) and fluence rate, respectively, in the analysis and interpretation of photobiological and photochemical processes. As a consequence, many equations that have been used in the past must be revised, and some experimental information (e.g. action spectra) needs to be re-analyzed.
Sucralose is an artificial sweetener persistently present in wastewater treatment plant effluents and aquatic environments impacted by human activity. It has a potential to accumulate in the water cycle due to its resistance to common water and wastewater treatment processes. This study examined UV/H2O2 advanced oxidation and found that hydroxyl substitution of the chlorine atoms on the sucralose molecule can form a carbohydrate consisting of fructose and sugar alcohol, very similar to environmentally benign sucrose. The second-order reaction rate constant for loss of parent molecule via reaction with hydroxyl radical was determined to be (1.56 ± 0.03)·109 M–1s–1. The degradation pathway involves substitution of a single chlorine by a hydroxyl group, with cyclic moiety being a preferential site for initial dechlorination. Further reaction leads to full dechlorination of the molecule, presumably via hydroxyl group substitution as well. No direct photolysis by UV wavelengths above 200 nm was observed. Because of its photostability when exposed to UV wavelengths ≥200 nm, known stability with ozone, limits of quantification by mass spectrometry close to or below environmental concentrations (<5 μg/L) without preconcentration, and otherwise stable nature, sucralose can be used as an in situ hydroxyl radical probe for UV-based and ozone-based AOP processes. As a compound safe for human consumption, sucralose makes a suitable full scale hydroxyl radical probe fit even for drinking water treatment plant applications. Its main drawback as a probe is lack of UV detection and as a result a need for mass spectrometry analysis.
COMPARISON AND STANDARDIZATION OF E.COLI PHOTOREPAIR UNDER DIFFERENT LAMPSThe effectiveness of UV disinfection is often reported without accounting for possible photorepair of microorganisms, although many microorganisms are known to repair their DNA after UV disinfection. The conditions of photorepair studies are not standardized and different lamp spectra and intensities are often used. The hypothesis that these lamp differences are significant in affecting the...Author(s)Zuzana BohrerovaKarl G. LindenSourceProceedings of the Water Environment FederationSubjectSession 2: Disinfection ResistanceDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2007ISSN1938-6478SICI1938-6478(20070101)2007:1L.55;1-DOI10.2175/193864707787932711Volume / Issue2007 / 1Content sourceDisinfection and Reuse SymposiumFirst / last page(s)55 - 62Copyright2007Word count167
COMPARATIVE EFFECTIVENESS OF UV AND CHLORINE FORINACTIVATION OF PARTICLE ASSOCIATED COLIFORMWastewater disinfection is challenged by particles in the wastewater effluent that may protect pathogens from lethal doses of disinfectants. Ultraviolet (UV) light and chlorine are two disinfectants that are common for use in wastewater. Typically, one or the other disinfectant is utilized. Over the ranges of disinfection doses applied for wastewater, UV disinfection can inactivate non-particle...Author(s)Banu ÖrmeciKarl G. LindenSourceProceedings of the Water Environment FederationSubjectSESSION 8: DISINFECTION RESISTANCE AND EMERGING PATHOGENSDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2002ISSN1938-6478SICI1938-6478(20020101)2002:1L.493;1-DOI10.2175/193864702785033923Volume / Issue2002 / 1Content sourceDisinfection and Reuse SymposiumFirst / last page(s)493 - 501Copyright2002Word count133
Hydraulic fracturing of unconventional gas wells utilizes large volumes of water-based fluid to increase formation permeability and, as a result, generates large amounts of wastewater as flowback. This water requires suitable treatment before being reused or discharged into the environment. A principal ingredient of flowback water is guar gum (a gelling agent), which may adversely affect advanced flowback water treatment such as membrane separation. This study demonstrates the potential of an activated sludge mixed liquor to degrade guar under typical flowback conditions [i.e., high concentrations of total dissolved solids (TDS)]. Guar was efficiently degraded at a TDS concentration of 1500 mg/L, with more than 90% of the dissolved chemical oxygen demand (CODd) having been removed after 10 h. Increasing the TDS concentration to 45000 mg/L inhibited CODd degradation to 60% removal after 31 h. A high TDS concentration additionally resulted in an increased effluent level of total suspended solids and turbidity; however, these were efficiently reduced using ferric chloride coagulation followed by sedimentation and filtration. Biological reduction of the guar concentration increased the flux of a bench-scale ultrafiltration membrane, demonstrating the potential of the process to treat flowback water prior to membrane separation.
