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1.
J Environ Sci (China) ; 90: 1-9, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32081306

RESUMO

Small diameter gravity sewers (SDGS) are extensively used to collect rural sewage as they are low in cost and quick to construct. However, the characteristics of biofilms in rural SDGS are still not clear. In this study, biofilms characteristics of aerobic rural SDGS were investigated using simulations in a lab under different flow conditions and slopes. Results indicated that the average thickness of aerobic rural SDGS biofilms was in the range of 350-650 µm, decreasing at locations with variable flow and high slopes. Protein was the most abundant substance in extracellular polymeric substance of SDGS biofilms. The most abundant bacteria, Proteobacteria, Actinobacteria, and Bacteroidetes, and functional bacteria showed different distributions when analyzed through Illumina HiSeq sequencing of 16S rRNA. The relative abundances of denitrifying bacteria, nitrite-oxidizing bacteria, and sulfate-reducing bacteria (SRB) were lower during variable flow than during stable flow. High slopes (15‰) decreased SRB presence, which could be used to mitigate H2S accumulation in aerobic SDGS. Overall, this study describes the characteristics of aerobic rural SDGS biofilms and provides valuable suggestions for the optimal design of SDGS based on these characteristics.


Assuntos
Biofilmes , Drenagem Sanitária , Matriz Extracelular de Substâncias Poliméricas , Esgotos , Bactérias , RNA Ribossômico 16S
2.
Environ Sci Pollut Res Int ; 26(34): 35270-35274, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31741277

RESUMO

Rodents infest urban environments, causing damage and acting as vectors for disease transmission. Currently, anticoagulants are the most widely used chemical rodenticides, and their extensive and widespread use can contaminate the environment. To ensure effectiveness and avoid accumulation of rodent baits in the environment, it is important to evaluate how long rodent baits maintain their palatability and efficacy. In rodent control programs, rodent baits are placed in locations such as sewers, but after a few days, baits appear altered, causing doubts about the control efficacy. For this reason, baits are replaced periodically, which increases costs and generation of chemical waste. The objective of this study was to evaluate the palatability and efficacy of commercial paraffin-type rodent bait blocks placed in sewers in São Paulo City over a period of 90 days. Bait blocks were placed in sewers and collected after 30, 60, and 90 days. Additionally, in a laboratory two-choice test, wild-caught urban Norway rats were offered 40-60 g of bait and an equal volume of standard rat pellets. The amount of bait and rat pellet consumed was registered, the palatability was calculated, and the efficacy was measured as the percentage mortality over 14 days. The results showed that, even when they had an altered appearance, bait blocks remained palatable to the rats and were effective after at least 90 days. Leaving bait blocks for longer periods could be an effective strategy for reducing costs and could help to ensure the control of urban rodents in an environmentally sustainable way.


Assuntos
Drenagem Sanitária , Controle de Roedores/métodos , Animais , Anticoagulantes , Brasil , Meio Ambiente , Masculino , Ratos , Rodenticidas/análise
3.
Sci Total Environ ; 692: 1304-1321, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31539962

RESUMO

Demands on global water supplies are increasing in response to the need to provide more food, water, and energy for a rapidly growing population. These water stressors are exacerbated by climate change, as well as the growth and urbanisation of industry and commerce. Consequently, urban water authorities around the globe are exploring alternative water sources to meet ever-increasing demands. These alternative sources are primarily treated sewage, stormwater, and groundwater. Stormwater including roof-harvested rainwater has been considered as an alternative water source for both potable and non-potable uses. One of the most significant issues concerning alternative water reuse is the public health risk associated with chemical and microbial contaminants. Several studies to date have quantified fecal indicators and pathogens in stormwater. Microbial source tracking (MST) approaches have also been used to determine the sources of fecal contamination in stormwater and receiving waters. This review paper summarizes occurrence and concentrations of fecal indicators, pathogens, and MST marker genes in urban stormwater. A section of the review highlights the removal of fecal indicators and pathogens through water sensitive urban design (WSUD) or Best Management Practices (BMPs). We also discuss approaches for assessing and mitigating health risks associated with stormwater, including a summary of existing quantitative microbial risk assessment (QMRA) models for potable and non-potable reuse of stormwater. Finally, the most critical research gaps are identified for formulating risk management strategies.


Assuntos
Drenagem Sanitária , Chuva , Esgotos/microbiologia , Microbiologia da Água , Monitoramento Ambiental , Abastecimento de Água/estatística & dados numéricos
4.
Water Sci Technol ; 80(2): 274-281, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537763

RESUMO

Connecting storm-sewers located at rather different elevations may be made with vortex drop shafts in which the energy dissipation is made by the friction between the vertical shaft and the flow and downstream by the impinging jet in a dissipation chamber. Following the first model design in the 1940s, different types of vortex drop shafts have been developed. One of the most used type is the so-called spiral vortex drop shaft developed to work in supercritical flow with good performance in both energy dissipation and space constrains. In this paper, an experimental flow characterization in a spiral vortex drop shaft is conducted covering the three main components of these structures, namely the inlet channel, the vertical shaft and the dissipation chamber. The results include measurement of water depths, pressure and velocity.


Assuntos
Drenagem Sanitária , Movimentos da Água , Baías , Pressão
5.
Sci Total Environ ; 689: 1192-1200, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31466159

RESUMO

This work for the first time shows possible advantage of using ferrous as a catalyst to selectively oxidise hydrogen sulphide in sewer water where biological activity is present. Ferrous catalysed the oxidation reaction in all conditions, but the oxygen requirement for the chemical oxidation of sulphide varied depending on the initial conditions (pH, concentrations of sulphide and oxygen). For initial concentrations of O2 and S2- exceeding 2 mg/L, and a pH between 7.3 and 8.3, approximately 1 mg-O2 was required to oxidise 1 mg-S2-. For the typical conditions experienced in a sewer (pH < 8.0 and O2 and S2- < 2.0 mg/L), approximately 2.0 mg-O2 is required to oxidise 1 mg-S2-. The most efficient O2 usage of 0.25-0.5 mg-O2 was observed with initial O2 and S2- concentrations below 2.0 mg/L and a pH >8.1. The developed mathematical model described the experimental results over a wide range using only three coefficients. The catalytic effect of ferrous selectively increased the oxidation rate of S2- in sewer water samples in which biochemical oxygen utilisation competes for oxygen. Further trials are needed to optimise the method for application in sewer systems where biofilm is present and varying conditions (temperature, H2S concentration, oxygen consumption rate) exist.


Assuntos
Drenagem Sanitária , Sulfeto de Hidrogênio/análise , Eliminação de Resíduos Líquidos/métodos , Biofilmes , Corrosão , Concentração de Íons de Hidrogênio , Oxirredução , Oxigênio , Esgotos , Sulfetos
6.
Environ Sci Pollut Res Int ; 26(26): 26563-26576, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31292865

RESUMO

In order to mitigate urban flooding and combined sewer overflows, an integrated assessment method was proposed to identify the optimum reconstruction scheme of a drainage system by considering environment, economy, and society. The integrated assessment framework consisted of the drainage system model establishment, analytic hierarchy process theory, and regret value method. Five drainage system reconstruction schemes for Chaohu city were proposed in this study, and they were evaluated according to nine assessment factors by the integrated assessment method at the initial and future stages. The integrated assessment results show that setting up interceptive equipment for a combined drainage network is the optimal reconstruction scheme at both the initial and future stages of the life cycle. This means that an interceptive combined drainage network is better than a separate drainage network or setting up storage tanks in particular situations from a comprehensive perspective.


Assuntos
Drenagem Sanitária , Inundações , Cidades , Drenagem Sanitária/métodos , Modelos Teóricos
7.
Water Res ; 162: 11-21, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31254882

RESUMO

Urban drainage system (UDS) researchers have applied the concept of resilience for minimizing the magnitude and duration of urban flooding in response to climate change. Currently, the relationship between conventional design and resilience analysis still remains unknown, while persistent rain has not been included in resilience assessment. The present study proposes new metrics by means of resilience profile graph for UDS stressed by synthetic short-duration storms and real persistent rains. The graph unifies the concepts of reliability, robustness, resilience and failure, as well as design standards for sewer surcharging, sewer flooding and property flooding, which are linked into curves to show a complete performance under climate stress scenarios. The obtained results show that resilience profile curves for short-duration storms are well fitted by power functions with coefficient of determination 98.13%-99.9%. Chicago hyetograph was used as critical input hyetograph where the error range was -0.34%-6.83% compared with actual hyetograph. Resilience profile graphs for persistent rains reveal that resilience assessment based on short-duration storms underestimates the effect of persistent rains, and it can be obtained by using segmental and reference reliability metrics to reduce working time from weeks to hours. For the rain of the same intensity, resilience to persistent rain was 18.4-33.1% lower than for single rains. Threat of persistent rain doesn't fall under the rains of high intensity but under large rainfall in total (which exceeds 25% of local annual rainfall), while re-planning water landscape as retarding basin reduces the impact of persistent rains to 5.8-11.8%.


Assuntos
Modelos Teóricos , Chuva , Chicago , Cidades , Mudança Climática , Drenagem Sanitária , Inundações , Reprodutibilidade dos Testes
8.
Environ Monit Assess ; 191(6): 343, 2019 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-31055667

RESUMO

The characteristics of surface runoff and the infiltration properties of urban green land are important to determine the effects of runoff reduction by low-impact development (LID) facilities. In this paper, two typical types of urban green land (lawn and shrub) in Shanghai were selected to study the runoff characteristics under eight rainfall events. The sensitivity of the runoff parameters was analyzed, and then, the optimal parameters were determined using the Stormwater Management Model (SWMM). The results showed that the interception and infiltration capacities of shrub were greater than those of lawn. The rainfall intensity and rainfall pattern were the major factors that influenced the interception and infiltration of rainwater. The threshold value that generates runoff varied across the eight rainfall events ranged from 1.6 to 28.5 mm for lawn and 4.5 to 32.0 mm for shrub. The maximum reduction ratios of runoff and peak flow for shrub were 52 and 57% higher than them for lawn, respectively. The parameters for shrub were more sensitive to runoff and peak flow compared with those for lawn. Under light rainfalls with a short duration, the maximum infiltration rate and depression storage were more sensitive than those under heavy rainfalls with a long duration. Antecedent dry weather period was not found to be a sensitive parameter except for the shrub under light rainfalls. The relative errors of runoff and dynamic mean runoff (60 min) for lawn and shrub were within ± 9.5%. The errors of peak flow ranged between - 21 and 16.6%. The dynamic runoff characteristics and the parameters for lawn and shrub determined in this study can provide references for simulating urban runoff and planning LID areas.


Assuntos
Simulação por Computador , Drenagem Sanitária/métodos , Monitoramento Ambiental/métodos , Chuva , Movimentos da Água , Calibragem , China , Cidades , Poaceae/crescimento & desenvolvimento
9.
Water Sci Technol ; 79(6): 1060-1070, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31070586

RESUMO

Brazil faces a severe lack of wastewater coverage. Even in urban areas, wastewater is directly disposed of in watercourses without any treatment for a large part of the population. Although the federal, state, and local governments have invested in water and wastewater services (WWS), the expected results have not been achieved. To overcome this problem, the present paper provides an opportunity to observe an ex-ante regulatory impact assessment (RIA) as a policy tool in Brazil. The regulatory policy options will be appraised through the multiple criteria decision analysis (MCDA) according to the following objectives: (i) protect the customers with respect to social aspects; (ii) safeguard the economic, operational and infrastructure sustainability; and (iii) protect the environment. The results show that by making decisions based on evidence, policy makers should reduce the households not connected to wastewater services by 75% and for that they should incur BRL 33 million to the year 2023. Hence, the extra revenues to be obtained with these new connections are capable of making a surplus estimated as BRL 42 million for the same period. This study promotes the use of RIA as a rational, robust and transparent decision framework by the regulatory agencies worldwide.


Assuntos
Drenagem Sanitária/métodos , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Brasil , Tomada de Decisões , Técnicas de Apoio para a Decisão , Drenagem Sanitária/legislação & jurisprudência , Política Ambiental
10.
Water Sci Technol ; 79(6): 1113-1122, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31070591

RESUMO

Sediment deposition in sewers and urban drainage systems has great effect on the hydraulic capacity of the channel. In this respect, the self-cleansing concept has been widely used for sewers and urban drainage systems design. This study investigates the bed load sediment transport in sewer pipes with particular reference to the non-deposition condition in clean bed channels. Four data sets available in the literature covering wide ranges of pipe size, sediment size and sediment volumetric concentration have been utilized through applying decision tree (DT), generalized regression neural network (GR) and multivariate adaptive regression splines (MARS) techniques for modeling. The developed models have been compared with conventional regression models available in the literature. The model performance indicators, showed that DT, GR and MARS models outperform conventional regression models. Result shows that GR and MARS models are comparable in terms of calculating particle Froude number and performing better than DT. It is concluded that conventional regression models generally overestimate particle Froude number for the non-deposition condition of sediment transport, while DT, GR and MARS outputs are close to their measured counterparts.


Assuntos
Árvores de Decisões , Drenagem Sanitária/estatística & dados numéricos , Sedimentos Geológicos/análise , Modelos Estatísticos , Redes Neurais de Computação , Poluição da Água/estatística & dados numéricos , Análise Multivariada , Eliminação de Resíduos Líquidos/estatística & dados numéricos
11.
Water Sci Technol ; 79(6): 1152-1163, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31070595

RESUMO

Urban flooding due to accelerated urbanization and the resulting drainage problems have become a worldwide issue and the subject of several studies in recent decades. Alternative and holistic approaches such as sustainable drainage systems have been gaining prominence. Compensatory techniques represent one of these promising alternatives for managing flooding risk in the transition to regenerative urban environments. The goal of this study is to assess the effect of a drainage network together with compensatory techniques on the susceptibility to urban flooding in Campeche District. This study applies the analytical hierarchy process together with a consistency analysis, using overlapping influential parameters in three scenarios. The results show that introducing a drainage system decreases the susceptibility to urban flooding in approximately 27% of Campeche District. In general, considering the absence of a drainage network, it is concluded that its implementation together with compensatory structures provides a reduction of approximately 32% in the susceptibility to urban flooding. It should be noted that, although costly, interventions for the implementation of a drainage infrastructure associated with compensatory techniques are extremely important for disaster reduction and sustainable development.


Assuntos
Drenagem Sanitária , Inundações/estatística & dados numéricos , Cidades , Desastres , Modelos Teóricos , Urbanização
12.
Water Sci Technol ; 79(4): 771-778, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30975943

RESUMO

This study has been carried out to evaluate the applicability of the pilot scale hybrid type of stormwater runoff treatment system for treatment of combined sewer overflow. Also, to determine the optimum operation parameter such as coagulation dosage concentration, effectiveness of coagulant usage, surface loading rate and backwashing conditions. The pilot scale stormwater filtration system (SFS) was installed at the municipal wastewater plant serving the city of Cheongju (CWTP), Korea. CWTP has a capacity of 280,000 m3/day. The SFS consists of a hydrocyclone coagulation/flocculation with polyaluminium chloride silicate (PACS) and an upflow filter to treat combined sewer overflows. There are two modes (without PACS use and with PACS use) of operation for the SFS. In case of no coagulant use, the range of suspended solids (SS) and turbidity removal efficiency were 72.0-86.6% (mean 80.0%) and 30.9-71.1% (mean 49.3%), respectively. And, the recovery rate of filter was 79.2-83.6% (mean 81.2%); the rate of remaining solid loading in filter media was 16.4-20.8% (mean 18.8%) after backwashing. The influent turbidity, SS concentrations were 59.0-90.7 NTU (mean 72.0 NTU), 194.0-320.0 mg/L (mean 246.7 mg/L), respectively. The range of PACS dosage concentration was 6.0-7.1 mg/L (mean 6.7 mg/L). The range of SS and turbidity removal efficiency was 84.9-98.2 (mean 91.4%) and 70.7-96.3 (mean 84.0%), respectively. It was found that removal efficiency was enhanced with PACS dosage. The recovery rate of filter was 92.0-92.5% (mean 92.3%) the rate of remaining solid loading in filter media was 6.1-8.2% (mean 7.2%) after backwashing. In the case of coagulant use, the particle size of the effluent is bigger than influent particle size. The results showed that SFS with PACS use more effective than without PACS use in SS and turbidity removal efficiency and recovery rate of filter.


Assuntos
Drenagem Sanitária/métodos , Chuva , Eliminação de Resíduos Líquidos/métodos , Filtração , Floculação , República da Coreia , Águas Residuárias , Purificação da Água
13.
Environ Sci Pollut Res Int ; 26(16): 16596-16605, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30989602

RESUMO

Multi-level ditch area is a major component of the hydrographic net of plain area, China. Given the high concentration of nitrogen (N) in the surface water and vigorous biogeochemical interactions, ditch is likely to be the hot spots of N2O emission. However, N2O emission flux and emission factor (EF5r) of multi-level ditches have not been determined. To address this knowledge gap, a 1-year field work in three ditches with different levels in Chengdu Plain was conducted. It is found that the annual flux of N2O emission and EF5r was higher in the lateral (0.0020 and 83.94 µg m-2 h-1) and field ditches (0.0019 and 110.75 µg m-2 h-1) than in the branch ditch (0.0016 and 46.38 µg m-2 h-1, P < 0.05). It is found that parameters of groundwater level, discharge, precipitation, and NH4+ were the primary factors, and these parameters can model the N2O flux well. Furthermore, the content of NH4+ in the surface water of ditches presented better correlation with the emission of N2O than the content of NO3-. Therefore, controlling NH4+ emission and lessening fertilizer usage in summer may be key solutions for indirect reduction of N2O in Chengdu Plain.


Assuntos
Poluentes Atmosféricos/análise , Drenagem Sanitária , Água Doce/química , Água Subterrânea/química , Óxido Nitroso/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Fertilizantes/análise , Nitrogênio/análise , Estações do Ano
14.
Water Sci Technol ; 79(2): 231-239, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30865594

RESUMO

Infiltration and inflow (I/I) of extraneous water in separate sewer systems are serious concerns in urban water management for their environmental, social and economic consequences. Effective reduction of I/I requires knowing where excess water ingress and illicit connections are located. The present study focuses on I/I detection in the foul sewer network of a catchment in Trondheim, Norway, during a period without snowmelt or groundwater infiltration. Fiber-optic distributed temperature sensing (DTS) was used for the first time in Norway to detect I/I sources in tandem with closed-circuit television inspection (CCTV) and smoke testing. DTS was an accurate and feasible method for I/I detection, though it cannot identify exact types of failure and sources of I/I. Therefore, other complementary methods must be used, e.g. CCTV or smoke testing. However, CCTV was not completely useful in confirming the DTS results. This study provides practical insights for the rehabilitation and repair of sewer networks that suffer from the undesirable I/I of extraneous water.


Assuntos
Drenagem Sanitária/métodos , Tecnologia de Fibra Óptica , Movimentos da Água , Cidades , Noruega , Tecnologia de Sensoriamento Remoto , Esgotos
15.
Water Sci Technol ; 79(2): 334-341, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30865604

RESUMO

China has achieved significant progress on wastewater treatment and aquatic environmental protection. However, leakage (in- and exfiltration) of sewer systems is still an issue. By using the statistical data of water and wastewater in 2016 in China, and the person loads (PLs) of water and wastewater in Singapore, the leakage fractions of hydraulic flow, organic carbon (COD), nitrogen (N) and phosphorus (P) mass loading, and in-sewer COD biological removal in the sewer systems of China (except Hong Kong, Macau and Taiwan), Shanghai, Guangzhou and Beijing were reported for the first time. The fractions of hydraulic flow infiltration (13%, Shanghai and Guangzhou) and exfiltration (39%, China) were calculated. Except Beijing, whose sewer networks are under appropriate management with small leakage fractions, the exfiltration fractions of COD (including in-sewer biological COD removal) ranged from 41% (Shanghai) to 66% (China) and averaged 55%; N ranged from 18% (Shanghai) to 48% (China) and averaged 33%; and P ranged from 23% (Shanghai and Guangzhou) to 44% (China) and averaged 30%. The exfiltrated sewage, COD, N and P not only wastes resources, but also contaminates the aquatic environment (especially groundwater) and contributes to 'black and odorous water bodies'. In- and exfiltration in the sewer network leads to low influent COD concentration, C/N ratio and high inorganic solids and inert particulate COD concentrations of many municipal wastewater treatment plants (WWTPs) causing high cost for nutrient removal, poor resource recovery, additional reactor/settler volume requirement and other operational problems. Therefore, tackling sewer leakage is of primary importance to today's environment in China. Recommendations for the inspection of sewer systems and the rehabilitation of damaged sewers as well as the development of design and operation guidelines of municipal WWTPs tailored to the specific local sewage characteristics and other conditions are proposed.


Assuntos
Esgotos , Eliminação de Resíduos Líquidos/métodos , Poluição Química da Água/estatística & dados numéricos , China , Drenagem Sanitária , Odorantes , Eliminação de Resíduos Líquidos/economia , Eliminação de Resíduos Líquidos/estatística & dados numéricos , Águas Residuárias/análise , Águas Residuárias/química , Poluição Química da Água/análise , Poluição Química da Água/economia
16.
J Med Entomol ; 56(1): 181-191, 2019 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-30462285

RESUMO

Periplaneta americana (L.) (Blattaria: Blattidae), the American cockroach, is the most important invasive urban pest of sewer environments colonizing there with high significance of human public health and household allergens need to be controlled. Therefore this practical approach systematic review perform internationally to highlight and provide a detailed P. americana control in sewers. Of the 474 papers, 129 papers were selected to become this practical approach systematic review study of cockroach control in sewers. To control the American cockroaches, many studies have been conducted in various fields describing from an angle. The results were classified and discussed in getting cockroaches from sewers into buildings and their elimination, insecticide susceptibility, application of dust, bait and Inesfly paint insecticide formulations, biocontrol, and futuristic action categories. A recommending manner to achieve a successful P. americana cockroach control in sewers is using a combination of Integrated Pest Management (IPM) strategies resulted in significant reductions of cockroach infestations and asthma health outcomes. Use of P. americana breeding thelytoky, push-pull strategies and an automated sewer robot, and integrating health into the future buildings may be new approaches of P. americana control strategies.


Assuntos
Drenagem Sanitária , Controle de Insetos , Periplaneta , Animais , Repelentes de Insetos , Resistência a Inseticidas , Inseticidas , Óleos Voláteis
17.
Sci Total Environ ; 655: 374-383, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30471606

RESUMO

This research studied the bio-protection mechanism based on chemical gradients in diffusive exchange permeable reactive barriers, evaluating the thickness of the reactive layers in the treatment of concentrated acid mine drainage (AMD). Six bench-scale reactors were constructed with reactive layer thicknesses of 2.5, 5, and 7.5 cm in duplicate. The reactors were first fed a sulfated solution for 55 days, followed by concentrated AMD for 166 days. The change of feed to AMD mainly affected the reactors with thinner 2.5 cm layers in comparison to the reactors with 5 and 7.5 cm layers. Cu and Zn removal efficiency was practically 100% in all the reactors; however, in the thinner layer reactors, metal breakthrough occurred towards the end of the experiment concurrently with inhibitory metal concentrations in the reactive layers. On the contrary, the reactors with layer thicknesses of 5 and 7.5 cm evaluated did not present toxic concentrations of these metals at any of the monitoring points. The bio-protection criterion qD correctly predicted that the thin-layer reactor would be the most affected by the toxicity of AMD. The criterion also indicated that all the reactors should fail. Nevertheless, the fault in the thinner layer reactor registered in the effluent after >150 days; therefore, the possibility of failure in the 5 and 7.5 cm thickness reactors is not rejected, as it could have occurred if the experiment had continued.


Assuntos
Reatores Biológicos/microbiologia , Drenagem Sanitária/métodos , Recuperação e Remediação Ambiental/métodos , Mineração , Poluição da Água/prevenção & controle , Desenho de Equipamento , Água Subterrânea/química , Concentração de Íons de Hidrogênio , Modelos Teóricos , Poluentes Químicos da Água/análise
18.
Water Sci Technol ; 78(7): 1499-1508, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30427790

RESUMO

This study is related to distribution temperature sensing (DTS) in sewers for tracing illicit or unintended inflows to foul sewers. A DTS measurement is performed with a fiber optic cable that is installed at the invert of a sewer pipe in combination with a standalone laser/computer instrument. This set-up generates in-sewer temperature measurements with high resolutions in time (every minute) and space (every metre) along the cable over long periods of time (weeks on end). The prolonged monitoring period in combination with the high level of detail in the dataset allows the study of anomalies (i.e., unexpected temperatures and/or temperature variations at certain locations), even if these only occur very infrequently. The objective of this paper is to develop an automated tool to analyze the large data masses and identify anomalies caused by illicit or unintended inflows. In this study, an algorithm for detecting the temperature changes that are caused by both wastewater discharge and inflow of stormwater are developed. A comparison of the results of the automated procedure to the results of a manual assessment of the datasets (Elmehaven, Denmark) shows that the automated procedure performs very well.


Assuntos
Drenagem Sanitária , Temperatura , Eliminação de Resíduos Líquidos/métodos , Dinamarca , Lasers , Fibras Ópticas , Tecnologia de Sensoriamento Remoto , Esgotos , Águas Residuárias
19.
Water Sci Technol ; 78(7): 1587-1596, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30427799

RESUMO

Large air pockets can be trapped in storm sewer systems during intense rain events. Uncontrolled release of these air pockets may cause geysering and pressure surges, resulting in flooding, pipe failures and safety issues. Thus, there is a great need to develop methods to retrofit existing sewer systems and to provide guidance on system design. A large-scale physical model was established to evaluate air-control orifice plates in reducing geysering intensity by utilizing air cushion effects over the process of air escape. Experimental results indicate that the magnitude of pressure fluctuations can be reduced significantly with partially open vent pipes. The maximum pressure head can be reduced by approximately two-thirds, and the magnitude of relative pressure oscillation decreased by about 95% when the diameter ratio of the air-control orifice to the vent pipe is below 25%. Air-water mixture jets can be avoided in such cases. The effect of using multiple vent pipes with orifice plates was also evaluated and found to be effective. Thus, air-control vent pipes can be applied to alleviate geysering and related pressure transients.


Assuntos
Modelos Teóricos , Chuva , Eliminação de Resíduos Líquidos/métodos , Drenagem Sanitária/métodos , Inundações , Pressão
20.
Infect Control Hosp Epidemiol ; 39(10): 1254-1256, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30157984

RESUMO

In hospital sinks, a novel plastic drain cover was effective in preventing dispersal of gram-negative bacilli and fluorescent gel associated with splattering of flowing water. Our findings suggest that the sink drain covers could provide a simple means to reduce dissemination of pathogens from contaminated sinks.


Assuntos
Infecção Hospitalar/prevenção & controle , Contaminação de Equipamentos/prevenção & controle , Corantes Fluorescentes/análise , Bactérias Gram-Negativas/isolamento & purificação , Infecção Hospitalar/microbiologia , Drenagem Sanitária , Desinfecção das Mãos , Hospitais , Humanos , Plásticos , Águas Residuárias/microbiologia
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