Application of DVC-FISH method in tracking <i>Escherichia coli</i> in drinking water distribution networks

Sporadic detection of live (viable) <i>Escherichia coli</i> in drinking water and biofilm with molecular methods but not with standard plate counts has raised concerns about the reliability of this indicator in the surveillance of drinking water safety. The aim of this study was to determine spatial distribution of different viability forms of <i>E. coli</i> in a drinking water distribution system which complies with European Drinking Water Directive (98/83/EC). For two years coupons (two week old) and pre-concentrated (100 times with ultrafilters) water samples were collected after treatment plants and from four sites in the distribution network at several distances. The samples were analyzed for total, viable (able to divide as DVC-FISH positive) and cultivable <i>E. coli</i>. The results showed that low numbers of <i>E. coli</i> enters the distribution sytem from the treatment plants and tend to accumulate in the biofilm of water distribution system. Almost all of the samples contained metabolically active <i>E. coli</i> in the range of 1 to 50 cells per litre or cm² which represented approximately 53% of all <i>E. coli</i> detected. The amount of viable <i>E. coli</i> significantly increased into the network irrespective of the season. <br><br> The study has shown that DVC-FISH method in combination with water pre-concentration and biofilm sampling allows to better understand the behaviour of <i>E. coli</i> in water distribution networks, thus, it provides new evidences for water safety control

Separation of reducing sugars from lignocellulosic hydrolysate: Membrane experiments & system dynamic modelling

Separation of fermentable sugars after hydrolysis of lignocellulosic biomass plays a vital role in second-generation biofuel production. Byproducts and solid fractions generated during pretreatment and hydrolysis can have adverse effects on fermentation efficiency. Previous studies have shown that a maximum of 40% (w/w) of sugar yield can be obtained by sequential UF and NF permeate recovery. This study aimed to introduce a multi-step membrane filtration process to recover fermentable sugars while removing inhibitory bi-products. Fermentable sugar recovery was investigated using a recirculation flow between various stages of separation. The experimental results demonstrated that by introducing NF permeate recirculation to the UF unit a sequential UF/NF system can achieve 60% (w/w%) recovery of reducing sugars. Based on the experimental results, a ‘Simultaneous ultrafiltration and nanofiltration model’ was developed using system dynamics. The model was used to predict the final sugar concentration and sugar yield using sugar permeability in each membrane as the dynamic variability. The model predicts that high sugar permeability (or selective permeability) through the ultrafiltration mostly affects the efficiency of the system, which still is a challenge

Effect of biostimulation on biodegradation of dissolved organic carbon in biological filters

The addition of labile organic carbon (LOC) to enhance the biodegradation rate of dissolved organic carbon (DOC) in biological columns was studied. Acetate standard solution (NaAc) and Luria Bertrani (LB) medium were used as LOC as biostimulants in glass column system used for measurements of biodegradable dissolved organic carbon (BDOC). The addition of LOC related with the increase of total DOC in sample. The concentration of BDOC increased up to 7 and 5 times and was utilized after 24 min. contact time. The biodegradation rate constant was increased at least 26 times during adaptation-biostimulation period. There was a strong positive correlation between the biodegradation rate constant and the concentration of BDOC. Biostimulation period ranged from 24 to 53 h for NaAc biostimulant and from 20 to 168 h for LB. The study has shown that LOC could be used as stimulator to enhance the biodegradation rate of DOC during biofiltration

Comparison of phosphorus removal efficiency of conventional activated sludge system and sequencing batch reactors in a wastewater treatment plant

The aim of this study was to evaluate the effectiveness application of sequencing batch reactors (SBRs) for phosphorus removal compared to the conventional activated sludge (CAS) treatment system. The results showed that the removal efficiency of phosphorus reached about 99% at wastewater treatment plant with CAS system. At the same time, the maximum phosphorus removal efficiency can be achieved to 88% if the SBRs system operating parameters are optimized. Finally, this study demonstrated that even if granules are not fully developed, the SBR system is working with a good efficiency

Management of wastewater from landfill of inorganic fiberglass

ArticleSustainability is one of the key factors in smart environment management and include the reduction of environment footprint. The waste and wastewater management plans are aimed on actions to reduce the amount of waste and environmental pollution. This includes collection of waste, logistics, storage, processing or valorisation and also treatment. The aim of this research was to evaluate environmental pollution risk and to demonstrate one of the wastewater management schemes to reduce the pollution level. Evaluation of the better management scheme was performed in one of the landfills in Latvia, where fiberglass waste and other inorganic waste is stored. Onsite evaluation results demonstrated the need to develop a better wastewater management scheme of inorganic fiberglass landfill. After that, laboratory–scale experiments for conventional coagulation and biodegradation tests have been performed for efficient management

Monitorização em contínuo da qualidade microbiológica da água e biofilmes associados utilizando um sistema de células de fluxo

A VIMÁGUA, Empresa de Água e Saneamento de Guimarães e Vizela E.I.M., criada em 19 de Fevereiro de 2002, tem por missão o abastecimento de água para consumo humano. Como tal, a manutenção da qualidade da água potável desde a estação de tratamento de água até aos consumidores é uma das nossas preocupações. Contudo, os sistemas de distribuição de água potável estão continuamente expostos a um fluxo de matéria orgânica biodegradável e de microrganismos. Estes últimos podem formar estruturas nas paredes das condutas – biofilmes – que lhes permite uma maior resistência à desinfecção. Com o propósito de monitorizar a formação de biofilmes e a sua interacção na qualidade da água instalou-se um sistema de amostragem in situ – reactor de células de fluxo - para a monitorização da formação de biofilmes em sistemas de água potável, e testar métodos de detecção de microrganismos patogénicos. Ao longo do tempo foi monitorizado o número de bactérias cultiváveis e totais, assim como parâmetros físico-químicos da água que abastecia o reactor. Em paralelo, foram desenvolvidas sondas de PNA para a detecção rápida de vários microrganismos (Escherichia coli; Helicobacter pylori) e testadas em laboratório, estando já a ser aplicadas no sistema de células de fluxo.Os autores gostariam de agradecer o apoio financeiro concedido pela FCT (Bolsa de doutoramento SFRH/BD/4705/2001) e pelo projecto europeu SAFER (Contrato n°EVK1-CT-200200108).info:eu-repo/semantics/publishedVersio

New device for air disinfection with a shielded UV radiation and ozone

Received: February 1st, 2021 ; Accepted: May 2nd, 2021 ; Published: May 7th, 2021 ; Correspondence: [email protected] air disinfection has become particularly relevant recently because of the Covid-19 pandemics. A shielded device for air and surface disinfection with UV radiation and ozone has been developed. It contains 28 low intensity (11 W) UV lamps (254 nm) in a specially designed three-dimensional grid to provide a large flow cross-sectional area and long path for the air particles to be irradiated. The device can be used in medical institutions, veterinary clinics, manufacturing plants, public premises, poultry, and livestock farms. It does not generate air-ions and ozone concentrations do not exceed the allowed 8-hour average values. The large number of UV lamps and powerful fans ensure air disinfection in large rooms in a relatively short time (400 m3 h -1 ). Simultaneously, the floor surface under the appliance is disinfected. Disinfection efficiency tests demonstrated 99.9999% reduction for Escherichia coli, Staphylococcus aureus and Pseudomonas phage Φ6 aerosols within a single transfer through the system (10 seconds of treatment). The housing of the device protects from direct UV radiation; therefore, people can be in the room during the operation of the device

Removal of paraquat pesticide with Fenton reaction in a pilot scale water system

Advanced oxidation processes, such as the Fenton's reagent, are powerful methods for decontamination of different environments from recalcitrant organics. In this work, the degradation of paraquat (PQ)pesticide was assessed (employing the commercial product gramoxone) directly inside the pipes of a pilotscale loop system; the effect of corroded cast iron pipe and loose deposits for catalysing the process wasalso evaluated. Results showed that complete degradation of paraquat ([PQ]0 = 3.9 × 10−4 M, T = 20-30 ◦C,pH0 = 3, [H2O2]0 = 1.5 × 10−2 M and [Fe (II)] = 5.0 × 10−4 M,) was achieved within 8 h, either in lab scale orin the pilot loop. Complete PQ degradation was obtained at pH 3 whereas only 30 % of PQ was degraded atpH 5 during 24 h. The installation of old cast iron segments with length from 0.5 to 14 m into PVC pipe loopsystem had a significant positive effect on degradation rate of PQ, even without addition of iron salt; the longerthe iron pipes section, the faster was the pesticide degradation. Addition of loose deposits (mostly corrosionproducts composed of goethite, magnetite and a hydrated phase of FeO) also catalysed the Fenton reactiondue to presence of iron in the deposits. Moreover, gradual addition of hydrogen peroxide improved gramoxone degradation and mineralization. This study showed for the first time that is possible to achieve completedegradation of pesticides in situ pipe water system and that deposits and corroded pipes catalyse oxidation ofpesticides

Modelling water quality in drinking water distribution networks from real-time direction data

Modelling of contamination spread and location of a contamination source in a water distribution network is an important task. There are several simulation tools developed, however the significant part of them is based on hydraulic models that need node demands as input data that sometimes may result in false negative results and put users at risk. The paper considers applicability of a real-time flow direction data based model for contaminant transport in a distribution network of a city and evaluates the optimal number of flow direction sensors. Simulation data suggest that the model is applicable for the distribution network of the city of Riga and that the optimal number of sensors in this case is around 200

and optimization Authors

coagulation and ozonation-biofiltratio