scholarly journals Efficient removal of per- and polyfluoroalkyl substances (PFASs) in drinking water treatment: nanofiltration combined with active carbon or anion exchange

2019 ◽  
Vol 5 (11) ◽  
pp. 1836-1843 ◽  
Author(s):  
Vera Franke ◽  
Philip McCleaf ◽  
Klara Lindegren ◽  
Lutz Ahrens

Nanofiltration produces potable water, while adsorption materials GAC and AIX remove more PFASs from membrane retentate than from raw water.

2021 ◽  
Vol 9 (01) ◽  
pp. 512-524
Author(s):  
Konan Lopez Kouame ◽  
◽  
Nogbou Emmanuel Assidjo ◽  
Andre Kone Ariban ◽  
◽  
...  

This article presents an optimization of the drinking water treatment process at the SUCRIVOIRE treatment station. The objective is to optimize the coagulation and flocculation process (fundamental process of the treatment of said plant)by determining the optimal dosages of the products injected and then proposes a program for calculating the optimal dose of coagulant in order to automatically determine the optimal dose of the latter according to the raw water quality. This contribution has the advantage of saving the user from any calculations the latter simply enters the characteristics of the raw effluent using the physical interface of the program in order to obtain the optimum corresponding coagulant concentration. For the determination of the optimal coagulant doses, we performed Jar-Test flocculation tests in the laboratory over a period of three months. The results made it possible to set up a polynomial regression model of the optimal dose of alumina sulfate as a function of the raw water parameters. A program for calculating the optimal dose of coagulant was carried out on Visual Basic. The optimal doses of coagulant obtained vary from 25, 35, 40 and 45 mg/l depending on the characteristics of the raw effluent. The model obtained is: . Finally, verification tests were carried out using this model on the process. The results obtained meet the WHO drinkability standards for all parameters for a settling time of two hours.


2017 ◽  
Vol 17 (6) ◽  
pp. 1793-1800
Author(s):  
Y. Yan ◽  
M. Carter ◽  
A. Mercer

Abstract Pilot plant testing is invaluable for ascertaining the robustness of water treatment processes against raw water quality events such as turbidity and colour spikes, whether it be for stress testing of an existing process or designing of a new process. Unfortunately, the natural occurrence of such events (particularly colour) can be difficult to predict and commercial humic materials generally fail to closely match the indigenous natural organic matter (NOM) present in the raw water. Therefore, it is highly desirable to be able to simulate NOM event conditions. This paper describes a simple brewing method that we developed and used in our recent pilot plant evaluation of a proposed DAF/Ozone/BAC process for drinking water treatment. Using this method we successfully prepared, by using fallen leaves etc. collected from the local catchment area, large quantities of a concentrated NOM stock solution with its specific ultraviolet absorbance (SUVA), when diluted, very close to the median SUVA of historical NOM events. The brewed solution showed broadly similar NOM characteristics to those of the raw water encountered during the pilot investigation period in terms of molecular weight distribution and fractionation. The coagulation behaviour was also examined for the spiked and non-spiked raw water.


2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Nusa Idaman Said ◽  
Arie Herlambang

Contamination of rivers has reached an alarming level, especially in the rivers passing through major cities, agricultural areas and industrial areas. Among the contaminants that often appear dominant and very disturbing is the organic substance. The existence of high organic matter within the river water is often expressed in permanganate number that has passed the quality standard. River that contain high organic matter usually the water smell and the color is black, besides it can also cause disturbances in the water treatment process, which is an increasing use of coagulants, chlorine, activated carbon, and the emergence of substances that are not desired, and the quality of treatment results are unsatisfactory. Many ways to reduce the organic matter in river water, one of them is by using the biofilter honeycomb structure. The target of the reduction of organic substances is that the river water could be used as a raw drinking water quality standards or meet the category B, Regulation of Jakarta Governor Number 582, 1995. Raw water used for this study were taken from Krukut River which is the raw water for Regional Water Company PALYJA, Production Installation III Cilandak, South Jakarta and Cengkareng Drain river water, which is currently used as a source of raw water for PAM Taman Kota, West Jakarta using a biofilter reactor aerobic system, the capacity of 50 - 200 m3, Capasity of Blowers 300 l /min, Residence Time 6 hours up to 1 hour. Test results on the residence time of 1 hour, parameters pH, TSS, turbidity, organic substances, detergents, manganese, ammonia, nitrite, nitrate, can meet the standard, except for iron which still exceeds the standard. To improve the removal  efficiency of organic matter and iron, at the beginning of processing before entering into the drinking water treatment unit need to be added powder active carbon and an oxidizing agent with a sufficient dose. Keywords: Organic substances, biofilter, aerobic, honeycomb plastic media.


2019 ◽  
Author(s):  
◽  
Sibongile Elizabeth Magubane

Poly– diallyldimethylammonium chloride (poly-DADMAC) is an established coagulant in the treatment of drinking water. Reports have indicated that poly-DADMAC can degrade into a suspected carcinogenic form which is N-nitrosodimethylamine (NDMA). Consequently, water treatment plant operators are required to know the residual concentration of polyelectrolytes at various stages in the treatment process and the eventual quality of the treated water. Historical research has proven that, over the years, a number of methods such as extraction-spectrophotometry, fluorometry and tannic acid have been developed and implemented for the analysis of polymers in drinking water. However, they produced poor linearity, sensitivity and precision, high detection limits or produced false positives due to matrix effects. The laboratory method that has proven to be simple, affordable and accurate is the colloidal titration method. However, this method cannot be used at the plant for quick and accurate monitoring of poly-DADMAC. In this study, the aim was to fabricate a Lovibond portable colorimetric comparator device based on gold nanoparticles for colorimetric quantification and detection of poly-DADMAC in raw and treated potable water. The colorimetric disk and comparator was fabricated from 14 nm gold nanoparticles with the concentration of poly-DADMAC varying from 1 to 10 mg L-1. The addition of higher concentrations of poly-DADMAC resulted in the aggregation of gold nanoparticles with the colour changing from red to blue. The gold nanoparticles were prepared via the citrate reduction method. Characterisation of the gold nanoparticles was done by ultraviolet- visible (UV/VIS) spectrophotometry and transmission electron microscopy (TEM). The Lovibond comparator was fabricated with a colour filter disk for the screening of residual poly-DADMAC in raw and potable water. The colorimetric disk was printed on the plastic slide and inserted in the plastic compartment of the comparator. The Lovibond comparator was verified with raw and potable water samples from different sampling points in and around the Mhlathuze river area located in the province of KwaZulu-Natal, South Africa. Preliminary results showed that the developed colorimetric comparator device can visually detect poly-DADMAC concentrations lower than 1 mg L-1. The colour development was first developed on normal paper and then optimised by UV/VIS spectrophotometry. The method developed has a linear range from zero to 10 mg L-1 with the correlation coefficient of R=0.9954. The effectiveness of the device was investigated by doing a recovery study on a potable water sample. Potable water is water that is suitable for drinking. In this research, potable water refers to tap water. The potable water sample was spiked with 1 mg L-1 poly-DADMAC. This exercise was done three times. The acceptance criterion for recovery is 80 to 120%. The 3 recoveries that were obtained are 107.95, 91.26 and 100.3%. The average recovery was 99.84%. This shows that the proposed method can detect poly-DADMAC with the acceptable level of accuracy. One of the important parameters that a quality method must have is selectivity. This parameter shows that the method can accurately detect the analyte of interest in the midst of different matrices. This was done by analysing the raw water samples together with their treated samples. Physical-chemical parameters were also analysed to show the broader state of the samples. The poly-DADMAC results obtained from the UV/VIS spectrophotometer compared quite well with those obtained from using the Lovibond colorimetric filter. The limited observation of colours using our eyes is a major contributor of systematic errors during the application of colorimetric devices. Thus, such a limitation can be reduced by using CIELAB system. A gold nanoparticle-based colorimetric CIELAB system for detection of poly-DADMAC in potable and raw water was also demonstrated. The method is based on the application of a paper-based analytical device which is printed on the normal A4 white printing paper. Fully enclosed 6 X 9 hydrophobic wells were fabricated on this paper. This work provides a clear evidence of the application of CIELAB colour system, and thus, replacing the conventional spectrophotometric technique to quantify polymers. Results of this work showed that the intensity of the fabricated well is proportional to the concentration of the detected polymer. The change in colour (ΔE) was calculated for each fabricated well and clear evidence of the colour change was observed upon the variation of the polymer. Moreover to the application of ΔE, the chromaticity using CIEYxy was used to verify colour change, it was observed that they followed the expected shift from red to blue, symbolising aggregation due to Van Der Waal inter-particle attractions as a result of the addition of poly-DADMAC. The results of this experiment were validated using the spectrophotometric technique which further emphasised the appearance of the new surface Plasmon resonance peak formed at 610nm symbolising aggregation. Importantly, the intensity of the new Surface Plasmon Resonance (SPR) peak at 610 nm increased by increasing the concentration of poly-DADMAC. Comparison of the Lovibond and UV/VIS results showed that there was no significant difference between the two methods. This proved that the fabricated Lovibond colour comparator is capable of the detection of residual poly-DADMAC in water treatment. This therefore implies that plant operators can be able to detect poly-DADMAC at any stage during the water treatment process by using a rapid, user-friendly portable device.


2021 ◽  
Author(s):  
Ikuro Kasuga ◽  
Hitomi Nakamura ◽  
Futoshi Kurisu ◽  
Hiroaki Furumai

Abstract Microbial regrowth in premise plumbing is a threat to water safety. Disinfectant residuals are often diminished during water transportation and stagnation, leading to the regrowth of opportunistic pathogens. Although microbial regrowth potential is mostly determined by water treatment, little is known about how each treatment step affects two key factors that contribute to microbial regrowth potential: biodegradable organic matter and microbial abundance. In this study, we operated annular reactors to evaluate the microbial regrowth potential of water shaped after each treatment step in a full-scale drinking water treatment plant with ozonation and biological activated carbon filtration. The assimilable organic carbon and total cell count (TCC) were stable at all treatment steps during the sampling period from July to October 2015. The assimilable organic carbon consumption and TCC net increase in the annular reactors indicated that apparent growth yields (cell number base) of microbial communities were different in each reactor. Regrowth potential evaluated by indigenous microbial community in finished water was reduced to 22% of that in raw water, while 75% of assimilable organic carbon in raw water remained in finished water. It suggested that treatment performance evaluated by indigenous microbial communities was better than that evaluated by assimilable organic carbon.


2001 ◽  
Vol 43 (12) ◽  
pp. 225-228 ◽  
Author(s):  
K. Lahti ◽  
J. Rapala ◽  
A-L. Kivimäki ◽  
J. Kukkonen ◽  
M. Niemelä ◽  
...  

Problems caused by cyanobacteria are common around the world and also in raw water sources of drinking water treatment plants. Strains belonging to genera Microcystis, Anabaena and Planktothrix produce potent hepatotoxins, the microcystins. Laboratory and pilot scale studies have shown that microcystins dissolved in water may pass the conventional surface water treatment processes. In 1998 the World Health Organization proposed a guide value of 1 μg/L for microcystin-LR (MC-LR) in drinking water. The purpose of this research was to study the occurrence of microcystins in raw water sources of surface waterworks and in bank filtration plants and to evaluate the removal of microcystins in operating waterworks. Four bank filtration plants and nine surface waterworks using different processes for water treatment were monitored. Phytoplankton was identified and quantified, and microcystins analysed with sensitive immunoassay. Microcystin occurrence in selected water samples was verified with HPLC and a protein phosphatase inhibition method. Microcystins were detected sporadically in raw water sources of most of the waterworks. In two raw water supplies toxins were detected for several months. The highest microcystin concentrations in incoming raw water were approximately 10 μg/L MC-LR equivalents. In treated drinking water microcystins were detected occasionally but the concentrations were always below the guide value proposed by WHO.


Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 933
Author(s):  
Mohamed Boussemghoune ◽  
Mustapha Chikhi ◽  
Fouzia Balaska ◽  
Yasin Ozay ◽  
Nadir Dizge ◽  
...  

This work concerns the preparation of a mineral membrane by the slip casting method based on zirconium oxide (ZrO2) and kaolin. The membrane support is produced from a mixture of clay (kaolin) and calcium carbonate (calcite) powders using heat treatment (sintering). Membrane and support characterization were performed by Scanning Electron Microscopy (SEM), X-ray Fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Raman Spectroscopy. The prepared mineral membrane was tested to treat drinking water obtained from different zones of the El Athmania (Algeria) water station (raw, coagulated, decanted, and bio filtered water). Experimental parameters such as permeate flux, turbidity, and total coliforms were monitored. The results showed that the mineral membrane was mainly composed of SiO2 and Al2O3 and the outer surface, which represented the membrane support, was much more porous than the inner surface where the membrane was deposited. The permeate flux of the raw water decreased with filtration time, due to a rejection of the organic matters contained in the raw water. Moreover, the absence of total coliforms in the filtrate and the increase in concentration in the concentrate indicate that the prepared mineral membrane can be used for drinking water treatment.


2019 ◽  
Vol 19 (6) ◽  
pp. 1579-1586 ◽  
Author(s):  
Xiang-Ren Zhou ◽  
Yi-Li Lin ◽  
Tian-Yang Zhang ◽  
Bin Xu ◽  
Wen-Hai Chu ◽  
...  

Abstract The objective of this research was to study the occurrence and seasonal variations of disinfection by-products (DBPs), including traditional carbonaceous and emerging nitrogenous DBPs, in a full-scale drinking water treatment plant (DWTP) for nearly 2 years. The removal efficiencies of each DBP through the treatment processes were also investigated. This DWTP takes raw water from the Yangtze River in East China. The quality of the raw water used in this DWTP varied with different seasons. The results suggested that DBP concentrations of the finished water were higher in spring (82.33 ± 15.12 μg/L) and summer (117.29 ± 9.94 μg/L) with higher dissolved organic carbon (DOC) levels, but lower in autumn (41.10 ± 5.82 μg/L) and winter (78.47 ± 2.74 μg/L) with lower DOC levels. Due to the increase of bromide concentration in spring and winter, more toxic brominated DBPs increased obviously and took up a greater proportion. In this DWTP, DBP concentrations increased dramatically after pre-chlorination, especially in summer. It is noteworthy that the removal of DBPs during the subsequent treatment was more obvious in spring than in the other three seasons because the pH value is more beneficial to coagulation in spring.


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