Adjusting for the operational environment in studies of performance measurement is very important, otherwise the analysis may lead to unrealistic scores, especially when its influence on costs is ...high, such as in the water utilities. In this paper, we study the influence of exogenous variables on the water utilities performance by applying conditional efficiency measures based on the order-m method and its probabilistic formulation. We use a sample of 66 water utilities operating between 2002 and 2008, representing about 70% of the Portuguese population. Our research suggests that inefficiency of Portuguese water utilities is substantial for some utilities: several exogenous variables might influence it considerably. For example, regulation has a positive influence on efficiency but when drinking water supply and wastewater services are provided by the same utility or when the wholesale and retail activities are provided together, the performance is lower. The effect of ownership is inconclusive and the variables residential customers, water source, peak factor, and density of customers have a mixed influence on performance which varies according to their scores.
► We found that the operational environment influences the water utilities efficiency. ► Regulation has a positive influence on performance. ► The joint provision of water and wastewater has an adverse effect on performance. ► We also found that the effect of ownership is inconclusive. ► The customers and their density, water source and peak factor have a mixed influence.
The deadliest coronavirus disease 2019 (COVID-19) is taking thousands of lives worldwide and presents an extraordinary challenge to mental resilience. This study assesses mental health status during ...the COVID-19 pandemic and its associated factors among informal waste workers in Bangladesh. A cross-sectional survey was conducted in June 2020 among 176 informal waste workers selected from nine municipalities and one city corporation in Bangladesh. General Health Questionnaire (GHQ-12) was used to assess respondents' mental health. The study found that 80.6% of the individuals were suffering from psychological distress; 67.6% reported anxiety and depression, 92.6% reported social dysfunction, and 19.9% reported loss of confidence. The likelihood of psychological distress (Risk ratio RR: 1.23, 95% confidence interval CI: 1.02-1.48) was significantly higher for female than male. Multiple COVID-19 symptoms of the family members (RR: 1.20, 95% CI: 1.03-1.41), unawareness about COVID-19 infected neighbor (RR: 1.21, 95% CI: 1.04-1.41), income reduction (RR: 1.60, 95% CI: 1.06-2.41) and daily household meal reduction (RR: 1.34; 95% CI: 1.03-1.73) were also found to be associated with psychological distress. These identified factors should be considered in policy-making and support programs for the informal waste workers to manage the pandemic situation as well as combating COVID-19 related psychological challenges.
The WHO Consensus Document on the epidemiology of the SARS epidemic in 2003, included a report on a concentrated outbreak in one Hong Kong housing block which was considered a 'super-spreading ...event'. The WHO report conjectured that the sanitary plumbing system was one transmission route for the virus. Empty U-traps allowed the aerosolised virus to enter households from the sewerage system. No biological evidence was presented. This research reports evidence that pathogens can be aerosolised and transported on airstreams within sanitary plumbing systems and enter buildings via empty U-traps. A sanitary plumbing system was built, representing two floors of a building, with simulated toilet flushes on the lower floor and a sterile chamber with extractor fan on the floor above. Cultures of a model organism, Pseudomonas putida at 106-109 cfu ml-1 in 0·85% NaCl were flushed into the system in volumes of 6 to 20 litres to represent single or multiple toilet flushes. Air and surface samples were cultured on agar plates and assessed qualitatively and semi-quantitatively. Flushing from a toilet into a sanitary plumbing system generated enough turbulence to aerosolise pathogens. Typical sanitary plumbing system airflows (between 20-30 ls-1) were sufficient to carry aerosolised pathogens between different floors of a building. Empty U-traps allowed aerosolised pathogens to enter the chamber, encouraging cross-transmission. All parts of the system were found to be contaminated post-flush. Empty U-traps have been observed in many buildings and a risk assessment indicates the potential for high risk cross-transmission under defect conditions in buildings with high pathogen loading such as hospitals. Under defective conditions (which are not uncommon) aerosolised pathogens can be carried on the airflows within sanitary plumbing systems. Our findings show that greater consideration should be given to this mode of pathogen transmission.
The 2021 volcanic eruption at La Palma, Canary Islands, was the island's most voluminous historical eruption. Little is known about this volcano's feeding system. During the eruption, seismicity was ...distributed in two clusters at ~10-14 km and ~33-39 km depth, separated by an aseismic zone. This gap coincides with the location of weak seismic swarms in 2017-2021 and where petrological data have implied pre-eruptive magma storage. Here we use seismological methods to understand the seismic response to magma transfer, with 8,488 hypocentral relocations resolving small-scale seismogenic structures, and 156 moment tensors identifying stress heterogeneities and principal axes flips. Results suggest a long-lasting preparatory stage with the progressive destabilisation of an intermediate, mushy reservoir, and a co-eruptive stage with seismicity controlled by the drainage and interplay of two localised reservoirs. Our study provides new insights into the plumbing system that will improve the monitoring of future eruptions in the island.
A Changing Framework for Urban Water Systems Hering, Janet G; Waite, T. David; Luthy, Richard G ...
Environmental science & technology,
10/2013, Letnik:
47, Številka:
19
Journal Article
Recenzirano
Odprti dostop
Urban water infrastructure and the institutions responsible for its management have gradually evolved over the past two centuries. Today, they are under increasing stress as water scarcity and a ...growing recognition of the importance of factors other than the cost of service provision are forcing a reexamination of long-held ideas. Research and development that supports new technological approaches and more effective management strategies are needed to ensure that the emerging framework for urban water systems will meet future societal needs.
The world is facing a pandemic of unseen proportions caused by a corona virus named SARS-CoV-2 with unprecedent worldwide measures being taken to tackle its contagion. Person-to-person transmission ...is accepted but WHO only considers aerosol transmission when procedures or support treatments that produce aerosol are performed. Transmission mechanisms are not fully understood and there is evidence for an airborne route to be considered, as the virus remains viable in aerosols for at least 3 h and that mask usage was the best intervention to prevent infection.
Heating, Ventilation and Air Conditioning Systems (HVAC) are used as a primary infection disease control measure. However, if not correctly used, they may contribute to the transmission/spreading of airborne diseases as proposed in the past for SARS.
The authors believe that airborne transmission is possible and that HVAC systems when not adequately used may contribute to the transmission of the virus, as suggested by descriptions from Japan, Germany, and the Diamond Princess Cruise Ship. Previous SARS outbreaks reported at Amoy Gardens, Emergency Rooms and Hotels, also suggested an airborne transmission.
Further studies are warranted to confirm our hypotheses but the assumption of such way of transmission would cause a major shift in measures recommended to prevent infection such as the disseminated use of masks and structural changes to hospital and other facilities with HVAC systems.
The Olburgen sewage treatment plant has been upgraded to improve the effluent quality by implementing a separate and dedicated treatment for industrial (potato) wastewater and reject water. The ...separate industrial treatment has been realized within a beneficial public-private partnership. The separate treatment of the concentrated flows of industrial wastewater and sludge treatment effluent proved to be more cost-efficient and area and energy efficient than a combined traditional treatment process. The industrial wastewater was first treated in a UASB reactor for biogas production. The UASB reactor effluent was combined with the reject water and treated in a struvite reactor (Phospaq process) followed by a one stage granular sludge nitritation/anammox process. For the first time both reactors where demonstrated on full scale and have been operated stable over a period of 3 years. The recovered struvite has been tested as a suitable substitute for commercial fertilizers. Prolonged exposure of granular anammox biomass to nitrite levels up to 30 mg/l did not result in inhibition of the anammox bacteria in this reactor configuration. The chosen option required a 17 times smaller reactorvolume (20,000 m(3) less volume) and saves electric power by approximately 1.5 GWh per year.
Green buildings are increasingly being plumbed with crosslinked polyethylene (PEX) potable water pipe. Tap water quality was investigated at a six month old plumbing system and chemical and odor ...quality impacts of six PEX pipe brands were examined. Eleven PEX related contaminants were found in the plumbing system; one regulated (toluene) and several unregulated: Antioxidant degradation products, resin solvents, initiator degradation products, or manufacturing aides. Water chemical and odor quality was monitored for new PEX-a, -b and -c pipes with (2 mg/L free chlorine) and without disinfectant over 30 days. Odor and total organic carbon (TOC) levels decreased for all pipes, but odor remained greater than the USA's Environmental Protection Agency's (USEPA) secondary maximum contaminant level. Odors were not attributed to known odorants ethyl-tert-butyl ether (ETBE) or methyl-tert-butyl ether (MTBE). Free chlorine caused odor levels for PEX-a1 pipe to increase from 26 to 75 threshold odor number (TON) on day 3 and affected the rate at which TOC changed for each brand over 30 days. As TOC decreased, the ultraviolet absorbance at 254 nm increased. Pipes consumed as much as 0.5 mg/L as Cl2 during each 3 day stagnation period. Sixteen organic chemicals were identified, including toluene, pyridine, methylene trichloroacetate and 2,4-di-tert-butylphenol. Some were also detected during the plumbing system field investigation. Six brands of PEX pipes sold in the USA and a PEX-a green building plumbing system impacted chemical and drinking water odor quality.
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•First US study detailing the impact of multiple PEX pipes on drinking water quality.•Eleven regulated and unregulated contaminants found in a PEX plumbing system.•For 30 days, odor and TOC levels decreased for six PEX brands sold in the USA.•PEX pipes caused odor that exceeded the USEPA SMCL even on day 30.•Disinfectant exposure sometimes caused greater odor levels for PEX pipes.
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