Assessment of the possibility of using flocculation to improve properties of ultrafiltration membranes used in the purification of swimming pool water system washings (original) (raw)
Related papers
Treatment of Pool Water Installation Washings in a Flocculation/Ultrafiltration Integrated System
Journal of Ecological Engineering
The article presents the possibilities of employing an integrated flocculation/ultrafiltration system in the treatment of washings generated upon the rinsing of filter beds in pool water installations. Single ultrafiltration process was used as a comparator. Flocculation was carried out using commercial dialuminium pentahydroxychloride solution widely used at pool facilities for the removal of contaminants in flocculation processes. The studies consisted in determination of correlations between the conditions of the flocculation process (variable doses of Al 3+ ions: from 4 to 280 mg/L) and the transport/separation characteristics of ultrafiltration membranes. Flocculation was performed at different temperatures of washings i.e. 8, 21, and 30°C for each of the pre-defined doses. Ultrafiltration was highly capable of reducing the turbidity of washings and removing a large group of contaminants as determined by turbidimetry and UV 254 absorbance measurements. The studies revealed that the best transport/ separation characteristics of ultrafiltration membranes were obtained in a system in which ultrafiltration was performed following flocculation of washings carried out at 21°C using a 40 mgAl 3+ /L solution. The turbidity was reduced by ca. 99% and UV absorption was reduced by ca. 94% while the relative volumetric stream of the permeate increased by more than 35% (as compared to the filtration of washings in a singleprocess system). Membrane ultrafiltration significantly increased the quality of the waste stream consisting of washings from the pool water installation. Pre-processing of washings is required before ultrafiltration in order to limit the blocking of membrane pores. Flocculation may be one of such pre-processing methods.
Application of Ultrafiltration in a Swimming Pool Water Treatment System
Membranes, 2019
Swimming pool water was treated using an ultrafiltration process using ceramic and polymer membranes for comparison. It was determined that the efficiency of the process depended on the type of membrane used. The polymer membrane decreased the absorbance and concentration of combined chlorine in the pool water to a greater extent than the ceramic membrane. In the case of a ceramic membrane, the concentration of combined chlorine in the permeate exceeded the limit values. During the ultrafiltration process, the permeate flux decreased, causing the blockage of membrane pores. The extent of this phenomenon was similar for both tested membranes. In the case of the ceramic membrane, flushing it with water could significantly restore its initial performance. For both tested membranes, a high regeneration efficiency was observed during chemical treatment with an alkaline solution. SEM photos of the polymer membrane showed low resistance of this polymer to the chlorine present in the swimmi...
The Use of Membrane Techniques in Swimming Pool Water Treatment
Journal of Ecological Engineering
The paper has determined the suitability of membrane processes (UF ultrafiltration, UF, and nanofiltration, NF) for the purification of waste streams, so-called backwash water, obtained from washing filtration beds in a swimming pool water system. The backwash water samples were taken from the circuits located in two indoor facilities with a different purpose of the basins. Moreover, the samples were characterized by varying quality, as described by selected physicochemical parameters (such as turbidity and ultraviolet absorbance UV254). Commercial membranes were used for the tests. The transport-separation properties of the membranes were determined based on the volumetric flux of the permeate. In addition, backwash water samples before and after the membrane process were subjected to toxicological assessment using the Microtox ® screening test. The performed processes contributed to a significant reduction in turbidity and the value of UV254 ultraviolet absorbance, both in the ultrafiltration and nanofiltration processes. Whereas, significant differences in transport properties were noted within individual processes. A great influence of backwash water quality, including physicochemical parameters, on the course and results of the membrane filtration processes was demonstrated. In all of the nanofiltration cycles carried out, the removal of the toxic properties of the backwash water with respect to bacteria in the Microtox ® test was found. Nevertheless, samples with high values of resultant physicochemical parameters after the ultrafiltration process were still characterized by high toxicity. Pressure membrane processes show high effectiveness in the removal of contaminants from backwash water. However, it is necessary to introduce supporting processes aimed at reducing membrane pore blocking by deposits and organic compounds, and in the case of ultrafiltration, assuring the safety of the purified stream in terms of the toxicological effect.
Application of Pressure-Driven Membrane Processes in Treatment of Swimming Pool Water System
Architecture, Civil Engineering, Environment, 2018
The paper presents usefulness of membrane processes (ultrafiltration (UF) and nanofiltration (NF)) for treatment of backwashing water of pool water system. The backwashings were taken from circulations located in two indoor facilities from pools of various functionalities. Moreover, the used samples had different quality in terms of physical and chemical parameters. The test used various membranes, both in respect of the polymer that they were made of and their separation capacity. Transport and separation properties of ultrafiltration (MW and V5) and nanofiltration (DK and HL) membranes were specified. Furthermore, backwashing water samples before and after membrane process treatment were subjected to Microtox ® toxicity test. The conducted processes helped to reduce turbidity and specific absorbance at UV 254nm 1m , both during ultrafiltration as well as nanofiltration. Much higher hydraulic performance was observed in ultrafiltration membranes. After each filtration cycle a Microtox ® toxicity test was carried out which revealed reduced washings toxicity in relation to bacteria in all tested samples.
Swimming pool water treatment by ultrafiltration–adsorption process
Journal of Membrane Science, 2008
Disinfection by-products are of great concern in swimming pool water where water treatment generally involves a disinfection step with chlorine. In fact, swimmers can contribute a large quantity of organic matter that can lead to the formation of chloramines, chloroform and chloroacetic acids. These compounds can lead to health problems among the staff and pool users, especially babies or little children. The water quality improvement and productivity performance of the hybrid process, ultrafiltration-adsorption, is investigated. An original work, this paper presents results obtained in a real pool system for the first time. An industrial unit was installed in a municipal swimming pool in Marseille (France) and the process was studied for more than 18 months. After a study on water quality according to pool usage (activity and number of swimmers), the influence of transmembrane pressure and filtration time on ultrafiltration performance was evaluated. Optimal ultrafiltration operating conditions were found to be at a transmembrane pressure (TMP) of 0.45 bar and a filtration time (T f ) of 60 min for the entire range of each water quality parameter studied. The filtration unit enabled water clarification, and the adsorption step limited the concentration of combined chlorine in water to 0.35 ppm, well below the limit given by the French legislation (0.6 ppm). Due to a succession of filtration and backwashes, permeability never decreased below 160 L h −1 m −2 bar −1 . In spite of difficult conditions in terms of frequent pool usage and total chlorine concentration, the membranes have shown promising flexibility in this hybrid process.
Ultrafiltration of activated sludge: Flocculation and membrane fouling
Desalination, 2011
The effect of flocculants on the ultrafiltration (UF) of activated sludge from a wastewater treatment plant, using organic membranes, was investigated. Flocculation trials were performed with commercial flocculants, ZETAG 7197 (an aliphatic polyamine) and Nalco MPE30 and MPE50 (cationic polymers). Optimal dosage was determined as a function of the mean floc size. Experiments were performed in a dead-end UF unit using polyethersulfone (PES) and regenerated cellulose (YM) flat membranes (10, 30, and 100 kDa) and in a crossflow UF-pilot plant unit, with a polyethersulfone (PES) membrane (100 kDa). Best results were obtained for the MPE50 flocculant. Membrane fouling was reduced at the optimal dosage of flocculant, while permeate collected was up to 20% of the feed volume. The total amount of permeate at the optimal dosage of MPE50 flocculant was 16-69% higher than without additives, depending on the MWCO (molecular weight cutoff), with an initial permeate flux increase of up to 80%. In the UF-pilot plant unit, a slight increase of permeate flux was observed at the optimal dosage of the flocculant, and more than 98% of chemical oxygen demand (COD) reduction was achieved.
Environmental Science & Technology, 2005
Membrane fouling is a critical limitation on the application of membranes to wastewater reuse. This work aims to understand the fouling phenomenon which occurs in ultrafiltration (UF; 17500 molecular weight cutoff (MWCO)) and nanofiltration (NF; 250 MWCO) membranes, with and without pretreatment. For this purpose, the molecular weight (MW) distribution of the organics has been used as a parameter to characterize the influent, the permeate and the foulant on the membrane surface. The variation of foulant concentration on the membrane due to pretreatment of the influent by flocculation and/or adsorption was investigated in detail. With the UF membrane, the peak of the MW distribution of organics in the permeate depended on the pretreatment; for example, the weight-averaged MW (M w) of 675 daltons without pretreatment shifted down to 314 daltons with pretreatment. In the case of the NF membrane, the M w of organics in the permeate was 478 daltons (without pretreatment) and 310 (with flocculation followed by adsorption). The M w of the organics in the foulant on the membrane surface was 513 daltons (UF) and 192 (NF) without pretreatment and 351 (UF) and 183 (NF) after pretreatment with flocculation followed by adsorption, respectively. Without the pretreatment, the foulant concentration was higher on both membranes. The difference was more significant on the UF membrane than on the NF membrane. For both membranes, the flocculation-and-then-adsorption pretreatment proved very effective.
2017
In the present work, we have conducted a study which is to study the mechanical and hydrodynamic performance (permeability and selectivity) of two asymmetric ultrafiltration membranes, the base matrix is polysulfone PSU UDEL P1700 [1-3]. The first type of these membranes is composed only of polysulfone and the second type is made from polysulfone and polystyrene expanded (PSe) [2]. Both membranes were used in the bleaching of waste water loaded with vat dyes (indigo and sulfur black) by using the technical ultrafiltration (UF), while optimizing the hydrodynamic and mechanical conditions of harvested membranes [2, 4]. The results of this study have been shown that the selectivity and the permeability of the PSU/PSe membrane are more efficient with respect to those of the membrane completely comprised of PSU, on the one hand, and the measured values of the fading rate water loaded with the black sulfur dyes and indigo were recorded respectively at percentages 60.78% and 80.36% appropr...
Separation and Purification Technology, 2008
Flocculation, adsorption onto powered activated carbon (PAC), and ultrafiltration (UF), alone and in combination, were tested for tertiary treatment of the secondary effluent from municipal wastewater treatment at the Ashkelon plant (in southern Israel). Encouraging and reliable results of total organic carbon (TOC) of <3 mg/l were achieved with a combination of 130 mg/l FeCl3, 0.6 g/l PAC and UF. The relative contribution of the UF membrane to the reduction of TOC changed with the molecular weight cut-off (MWCO) of the membrane, from a negligible 2.9% for a 100-kDa-MWCO membrane to 17% for 10- and 2-kDa membranes. The latter membranes, however, developed significant fouling, with a 35% drop in flux during first 30 min of the filtration cycle. The flux drop for the 50- and 100-kDa membranes was in the low range of ∼3%. The optimal MWCO interval of 20- to 50-kDa in combination with flocculation/PAC pretreatment gave a significant reduction in organic content with minimal membrane fouling. Detailed GC–MS analysis showed that the combined treatment gave very efficient retention of organic compounds with molecular weights below 800 Da, with the consequent absence of harmful compounds in the tertiary effluent. It was therefore concluded that the recommended flocculation/adsorption protocol constitutes an effective pretreatment for UF and that the obtained tertiary effluent can be used for unrestricted irrigation.