Levels and profiles of polychlorinated dibenzo-p-dioxin and dibenzofurans in raw and treated water from water treatment plants in Shenzhen, China

2016 ◽  
Vol 211 ◽  
pp. 233-240 ◽  
Author(s):  
Feina Lu ◽  
Yousheng Jiang ◽  
Dongting Wu ◽  
Jian Zhou ◽  
Shengnong Li ◽  
...  
2016 ◽  
Vol 17 (3) ◽  
pp. 752-758 ◽  
Author(s):  
Sam Hancock ◽  
Martin Harris ◽  
David Cook

Rapid monochloramine decay has been observed in the product water of three River Murray water treatment plants (WTPs). Previous investigations identified that rapid monochloramine decay was microbiological in nature and observed in samples taken after media filtration but was absent in filtered water samples from a fourth WTP of similar design. The filters at the WTP not exhibiting rapid decay are backwashed with filtered non-disinfected water whereas the other WTPs backwash with treated chloraminated water. It was therefore hypothesised that backwashing filters with chloraminated water was the cause of the rapid monochloramine decay. A pilot-scale study was conducted to investigate the impact of backwashing with chloraminated water on the occurrence of microbiologically accelerated monochloramine decay. Additional samples were analysed to assess the impact of chloraminated backwash water on N-Nitrosodimethylamine (NDMA) formation and biological degradation of taste and odour compounds 2-methyl isoborneol (MIB) and geosmin in the filter media. Backwashing with chloraminated filtered water was concluded to be the cause of the observed rapid monochloramine decay, with rapid decay observed within 8 weeks for the filters backwashing with chloramines. Additionally, backwashing with chloraminated filtered water was observed to increase NDMA formation and impair the biological degradation performance of MIB and geosmin.


Revista DAE ◽  
2019 ◽  
Vol 221 (68) ◽  
pp. 87-100
Author(s):  
Juscelino Alves Henriques ◽  
Marcelo Libânio ◽  
Veber Afonso Figueiredo Costa ◽  
Mariângela Dutra de Oliveira

As estações de tratamento de água (ETAs) têm um papel fundamental e estratégico no controle de doenças transmitidas pela água por meio da potabilização da água, para atender às necessidades da população que é abastecida por ela. Nesse contexto, a avaliação do desempenho dessas estações é primordial, particularmente para as entidades responsáveis pelo estágio de controle da qualidade da água, uma vez que a ETA deve apre- sentar e operar com condições mínimas necessárias para alcançar seu objetivo. Para o desenvolvimento dos modelos (Modelo 1 - com base na turbidez da água tratada e Modelo 2 - com base na cor aparente da água tratada) foram utilizados dados referentes à qualidade da água bruta e tratada, fatores operacionais e parâme- tros hidráulicos de 3 ETAs, com taxas de fluxo de 50 L.s-1 ou menos. Os modelos foram desenvolvidos usando a caixa de ferramentas do Matlab®, a partir da rede neural do tipo de camadas recorrentes, com função de ativação tansig e purelin. Como resultados, os modelos apresentaram coeficientes de determinação de 0,928 e 0,823 para turbidez e cor aparente da água tratada, respectivamente. Os resultados corroboram a aplicação da Inteligência Artificial em estações de tratamento de água, com o objetivo de otimizar processos e garantir uma maior operabilidade da ETAs, gerando um produto cada vez mais confiável. Palavras-chave: Desempenho da planta de tratamento de água. Processos de otimização. Rede neural artificial. Abstract The water treatment plants (WTP) have a fundamental and strategic role in the control of waterborne diseases through the potabilization of water, to meet the needs of the population that is supplied by it. In this context, evaluating the performance of these stations is paramount, particularly for the entities responsible for the water quality control stage, since WTP must present and operate with minimum conditions necessary to achieve its ob- jective. For the development of the models (Model 1 - based on turbidity of treated water and Model 2 - based on the apparent color of the treated water) data were used referring to raw and treated water quality, operational factors and hydraulic parameters of 3 WTPs, with flow rates of 50 L.s-1 or less. The models were developed usingthe Matlab® toolbox, from the neural network of the recurrent layers type, with activation function tansig and purelin. As results, the models presented regression coefficients of 0.928 and 0.823 for turbidity and apparent color of treated water, respectively. The results corroborate for the application of Artificial Intelligence in water treatment plants, with a view to optimizing processes and guaranteeing greater WTPs operability, generating an increasingly reliable product. Keywords: Water treatment plant performance. Optimization processes. Artificial Neural Network.


Author(s):  
Wonjin Sim ◽  
Sol Choi ◽  
Gyojin Choo ◽  
Mihee Yang ◽  
Ju-Hyun Park ◽  
...  

In this study, the concentrations of organophosphate flame retardants (OPFR) and perfluoroalkyl substances (PFAS) were investigated in raw water and treated water samples obtained from 18 drinking water treatment plants (DWTPs). The ∑13OPFR concentrations in the treated water samples (29.5–122 ng/L; median 47.5 ng/L) were lower than those in the raw water (37.7–231 ng/L; median 98.1 ng/L), which indicated the positive removal rates (0–80%) of ∑13OPFR in the DWTPs. The removal efficiencies of ∑27PFAS in the DWTPs ranged from −200% to 50%, with the ∑27PFAS concentrations in the raw water (4.15–154 ng/L; median 32.0 ng/L) being similar to or lower than those in the treated water (4.74–116 ng/L; median 42.2 ng/L). Among OPFR, tris(chloroisopropyl) phosphate (TCIPP) and tris(2-chloroethyl) phosphate (TCEP) were dominant in both raw water and treated water samples obtained from the DWTPs. The dominant PFAS (perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA)) in the raw water samples were slightly different from those in the treated water samples (PFOA, L-perfluorohexane sulfonate (L-PFHxS), and PFHxA). The 95-percentile daily intakes of ∑13OPFR and ∑27PFAS via drinking water consumption were estimated to be up to 4.9 ng/kg/d and 0.22 ng/kg/d, respectively. The hazard index values of OPFR and PFAS were lower than 1, suggesting the risks less than known hazardous levels.


Author(s):  
Atul Maldhure ◽  
Gajanan Khadse ◽  
Pawan Labhasewar

Abstract Polyaluminium chloride (PAC) with different basicity is used as a coagulant in most drinking water treatment plants (WTP). The aluminium concentration in PAC and its hydrolysis mechanism varied with the basicity of PAC. Incremental addition of PAC changes various Physico-chemical properties and turbidity removal mechanisms in water. Water treatment plants use the PAC concentration beyond its optimum dose without considering other aspects, including residual aluminium concentration. In the present work, the effect of high and medium basicity of PAC on different Physico-chemical properties like pH, zeta potential, and residual aluminium concentration of water was investigated. The pH of treated water decreases with the incremental addition of PAC, and an increase in zeta potential and residual aluminium concentration in treated water was evidenced. The change in pH after PAC addition is responsible for deciding the coagulation mechanism and efficiency of the coagulation process. pH reduction is comparatively more in high basicity PAC than medium basicity. PAC hydrolysis mechanism is controlled by the zeta potential of water and can be used as an alternative method to decide the optimum coagulant dose. The performance of clariflocculator and pulsator-based WTP was also evaluated for raw water from the same source. To reduce down the turbidity below the acceptable level, the coagulant requirement for clariflocculator based WTP is comparatively less than pulsator based WTP. The floc blanket in the pulsator gets disturbed with a slight change in the coagulant chemistry and quantity.


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