Membrane Filtration Method Research Articles

Modeling and fouling control in a hybrid membrane process using CuO-catalytic membrane coupled to ozone

Membrane filtration methods are prone to significant fouling, which lowers the efficiency of the operation. Hybrid techniques combining ozone and membrane filtration are promising for removing dissolved contaminants and reducing membrane fouling. However, a detailed knowledge of fouling processes is necessary to incorporate these technologies in large-scale water and wastewater treatment plants. Although fouling models for conventional membrane filtration systems are well established in the literature, modeling data for hybrid systems (combining membrane/advanced oxidative processes) with antifouling features are scarce. Therefore, a ceramic α-Al2O3/ZrO2 commercial membrane with a molecular weight cut off of 10 kDa was functionalized applying layer-by-layer deposition of CuO for application in a hybrid system (membrane/catalytic ozonation) to treat contaminated surface water. The findings show that CuO-membranes can mitigate membrane fouling during hybrid processes, enhancing total filtration efficiency in the treatment of surface water. A fitting model that incorporated Hermia’s law as well as surface and bulk reactions that contribute to fouling removal is proposed and was successfully applied. The model allowed parameters to be estimated for the coated and uncoated membranes in the presence or absence of ozone. Membrane reusability was also investigated.

Simultaneous solid-liquid separation and primary purification of clavulanic acid from fermentation broth of Streptomyces clavuligerus using salting-out extraction system.

Clavulanic acid (CA) is usually used together with other β‐lactam antibiotics as combination drugs to inhibit bacterial β‐lactamases, which is mainly produced from the fermentation of microorganism such as Streptomyces clavuligerus. Recently, it is still a challenge for downstream processing of low concentration and unstable CA from fermentation broth with high solid content, high viscosity, and small cell size. In this study, an integrated process was developed for simultaneous solid–liquid separation and primary purification of CA from real fermentation broth of S. clavuligerus using salting‐out extraction system (SOES). First, different SOESs were investigated, and a suitable SOES composed of ethanol/phosphate was chosen and further optimized using the pretreated fermentation broth. Then, the optimal system composed of 20% ethanol/15% K2HPO4 and 10% KH2PO4 w/w was used to direct separation of CA from untreated fermentation broth. The result showed that the partition coefficient (K) and recovery yield (Y) of CA from untreated fermentation broth were 29.13 and 96.8%, respectively. Simultaneously, the removal rates of the cells and proteins were 99.8% and 63.3%, respectively. Compared with the traditional method of membrane filtration or liquid–liquid extraction system, this developed SOES showed the advantages of simple operation, shorter operation time, lower process cost and higher recovery yield of CA. These results demonstrated that the developed SOES could be used as an attractive alternative for the downstream processing of CA from real fermentation broth.

Analysis of Wastewater Reveals the Spread of Diverse Extended-Spectrum β-Lactamase-Producing E. coli Strains in uMgungundlovu District, South Africa.

Wastewater treatment plants (WWTPs) are major reservoirs of antibiotic-resistant bacteria (ARB), favouring antibiotic resistance genes (ARGs) interchange among bacteria and they can provide valuable information on ARB circulating in a community. This study characterised extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli from the influent and effluent of four WWTPs in uMgungundlovu District, KwaZulu-Natal, South Africa. E. coli was enumerated using the membrane filtration method and confirmed using the API 20E test and real-time polymerase chain reaction. ESBL-producers were phenotypically identified by their susceptibility to the third-generation cephalosporins using the disc diffusion and the double-disc synergy methods against cefotaxime (30 µg) with and without 10 µg clavulanic acid. Genotypic verification was by PCR of the TEM, SHV, and CTX-M genes. The clonality of isolates was assessed by ERIC-PCR. The highest E. coli count ranged between 1.1 × 105 (influent) and 4.3 × 103 CFU/mL (effluent). Eighty pure isolates were randomly selected, ten from the influent and effluent of each of the four WWTP. ESBLs were phenotypically confirmed in 49% (n = 39) of the isolates, of which 77% (n = 30) were genotypically confirmed. Seventy-three percent of the total isolates were multidrug-resistant (MDR). Only two isolates were susceptible to all antibiotics. Overall, resistance to first and second-generation cephalosporins was higher than to third and fourth generation cephalosporins. Also, 15% of the isolates were resistant to carbapenems. The CTX-M-type ESBL (67%; n = 20) was the most common ESBL antibiotic resistance gene (ARG) followed by TEM (57%; n = 17) and SHV-types (27%; n = 8). Also, a substantial number of isolates simultaneously carried all three ESBL genes. ERIC-PCR revealed a high diversity of isolates. The diversity of the isolates observed in the influent samples suggest the potential circulation of different ESBL-producing strains within the studied district, requiring a more comprehensive epidemiological study to prevent the spread of ESBL-producing bacteria within impoverished communities.

Evaluation of the quality of groundwater in the municipality of Ji-Paraná, Rondônia, in the Brazilian Amazon region

Groundwater quality can be affected by many factors. The objective of this study was to assess the quality of groundwater and map the flow direction, to identify possible sources of contamination in the districts of Nova Londrina and Nova Colina (Ji-Paraná, Rondônia). Water samples were collected in September 2015 and February 2016 in 20 wells in Nova Londrina and in December 2016 and April 2017 in 15 wells in Nova Colina. The turbidity, pH and electrical conductivity (EC) were measured in loco. The microbiological parameters were determined by the membrane filtration method in a chromogenic medium, and the total dissolved solids (TDS) were measured by the gravimetric method. The nutrients ammonia, nitrite, nitrate, dissolved phosphorus and total phosphorus were ascertained by the spectrophotometric method and the underground flow was obtained by applying the Surfer 8.0 software. Through principal component analysis (PCA) it was possible to detect that the TDS, total coliforms, pH and EC had important contributions to formation of the groundwater axes in Nova Londrina, while the variables EC, nitrate and well and cesspit depths contributed in Nova Colina. The groundwater flow did not differ among the months studied, and was mainly in the northwest-southeast direction in Nova Londrina and from the southeast to other regions in Nova Colina.

Water Quality Assessment and Evaluation of Human Health Risk in Mutangwi River, Limpopo Province, South Africa.

Freshwater supply is essential to life on Earth; however, land use activities such as mining and agriculture pose a significant danger to freshwater resources and the wellbeing of aquatic environments. This study temporarily assesses the water quality characteristics of Mutangwi River. Physicochemical parameters (pH, temperature, total dissolved solids (TDS), salinity, electrical conductivity (EC), and turbidity) were determined in situ using an Extech multimeter and turbidity meter. The concentration of the selected metals (Mg, Cr, Fe, Cd, Mn, Pb, Ca, and Na) were analysed using an Atomic Absorption Spectrophotometer. Membrane filtration method was used to analyse microbiological parameters (Escherichia coli and Enterococci). The physicochemical water quality parameters as well as basic anions (fluoride, phosphate, sulfate, nitrate, and chloride) determined complied with the regulatory guideline of the World Health Organization (WHO) and the South Africa National Standards (SANS). Some of the trace metals (Mn, Ca, Fe, and Mg) were found below the guideline values, while others (Pb and Cd) exceeded the threshold limit. The counts for E. coli (814.5–2169 cfu/100 mL) and Enterococci (333–9396 cfu/100 mL) in the study did not comply with the regulatory guidelines. The water quality status using the water quality index (WQI) indicated that on the average, the water quality from Mutangwi River is poor (WQI > 100). The hazard quotient through ingestion exposure did not exceed the threshold limit of 1, for adults and children. This implies that there is no potential non-carcinogenic health risk from trace elements via ingestion of drinking water for children and adults. However, cancer risk for adults and children was computed in relation to Cd and Pb levels and exceeded the threshold limit 10−4, indicating a possible carcinogenic risk. Water from the river should be adequately treated prior to domestic and agricultural use.

Evaluation of Drinking Water Quality in Rural Area of Amhara Region, Ethiopia: The Case of Mecha District

This study was conducted to assess the drinking water quality of north Mecha district, Amhara Region, Ethiopia. 26 drinking water samples were collected from the water points of the dweller community in the dry seasons of 2020 and subjected to the analysis of physicochemical parameters, bacteriological parameters, and the level of trace metals. The analysis of physicochemical parameters and the trace metals was carried out following the standard procedures of the laboratory, and the bacteriological water qualities were measured using the membrane filtration method. The F−, NO3−, SO42−, and Cu levels of the water samples were within the permissible limits of the WHO and compulsory Ethiopian standard (CES). Depending on turbidity, 61.54% of the tested water samples crossed the WHO limit of drinking water quality, and 100% of the samples surpassed the limits of EPA. Based on iron and ammonia levels, 38.46%, and 100% of the studied water samples violated the environmental protection agency (EPA) guidelines; 23.07%, and 3.84%, of the samples surpassed the WHO and CES drinking water quality standards. In view of pH, 23.07% of the tested water samples were not within the safe limit of the WHO and CES. 92.31% of the studied water samples were not potable as coliform bacterium (thermo tolerant indicator bacterium) growth was detected. The study revealed that the water sources of the study area are not safe for drinking unless appropriate treatment measurements are taken. Higher values of water quality parameters for the water samples from Koga irrigation site than the values for the water samples from the study sites found out of the irrigation site indicated the pollution load of Koga irrigation on the water quality of the area.

MICROBIOLOGICAL ASSESSMENT OF BOREHOLES, SACHET AND BOTTLE WATER IN ANCHOR UNIVERSITY AND AYOBO COMMUNITY

The physicochemical and bacteriological quality of borehole, bottle and sachet water sold in Anchor University and within Ayobo community Lagos state, Nigeria was investigated Microbiological analysis was carried out using standard microbial procedure to ensure that the water is microbiologically safe. It was screened for the presence of coliforms and other pathogenic microorganisms. The total heterotrophic bacterial count for bottle, sachet and borehole water are 16.50-123.50 x 103CFU/ml, 65.00-73.00 x 103CFU/ml and 0.00-72.00 x 103CFU/ml respectively while the total heterotrophic fungal count for bottle, sachet and borehole water are 5.00-54.50 x 103CFU/ml, 11.00-27.50 x 103CFU/ml and 6.00-16.16.00 x 103CFU/ml respectively. Most probable number was determined using membrane filtration method and it ranged from 15MPN/100ml, 22MPN/100ml, and 27MPN/100 ml for bottle, sachet and borehole water respectively. The mean total coliform per 100ml ranged from 22-30 x 103CFU/ml while fecal coliform ranged from 4-11 x 103CFU/ml. The isolated organisms were Salmonella paratyphi, Shigella flexneri, Proteus vulgaris, Pseudomonas aeroginosa, Escherichia coli, Citrobacter freudii, Salmonella paratyphi, Aspergillus candidus, Aspergillus niger, Aspergillus sulphureus and Penicillium corylophilum. Most of the bacteria isolated showed multidrug resistance to Augmentin, Gentamycin, Pefloxacin, Tarivid, Streptomycin, Septrin, Chloramphenicol and Amoxacillin and showed susceptibility to Ciprofloxacin. The study therefore concludes that these water samples do not meet the WHO standards for potable water; hence they can be potential sources of waterborne diseases.

Efficiency and potential mechanism of complete Cr(VI) removal in the presence of oxalate by catalytic reduction coupled with membrane filtration

• A novel method via catalytic NaBH 4 /filtration reduced the total Cr was proposed. • Fe(III) or Al(III) improved the removal of the total Cr of Cr(VI)–Ox–NaBH 4 system. • About 4% of Cr(III) without settling naturally was easily intercepted by membrane. • Gradually releasing Ox from suspended solids caused Cr(III) natural precipitation. • It was found that impurity CO 3 2− can be reduced to formate by-products by NaBH 4 . The treatment of industrial wastewater containing Cr(VI)–organic compounds is a long-term concern in the field of environment. In order to realize the high-efficient reduction of Cr(VI) and solve the problem of Cr(III) residue in water environment, a novel catalytic chemical reduction/membrane filtration method was developed for the removal of total Cr (TCr) in a system with coexisting Cr(VI) and oxalate (Ox). The effects of the concentrations of Ox, Fe(III), and Al(III), the dosage of NaBH 4 , and sedimentation time on the removal of Cr(VI) containing Ox by NaBH 4 were investigated. Additionally, the simultaneous removal of turbidity and TCr using a microfiltration membrane was investigated, and the reason for the enhanced TCr removal was clarified. The results of ion chromatography (IC), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) suggested that when Cr(VI) and Ox coexist, low concentrations (0.3 mM) of Fe(III) or Al(III) contributed significantly to the high turbidity caused by the formation of suspended solids (SS) following the reduction of Cr(VI) by NaBH 4 . However, almost all the Cr(III) could be removed by a 1-μm microfiltration membrane. The high turbidity system formed by Ox and Cr(III) is unstable, and some Ox will gradually release their binding sites with Cr(III) with the extension of the natural settling time. For 24 h, 53.75% of Ox was involved in the formation of SS, while in the presence of Fe(III) or Al(III), only 11.28% and 6.30% of Ox were involved, respectively. High concentrations of Fe(III) and Al(III) enhanced the reduction of Cr(VI) by NaBH 4 . The removal of TCr was close to 100% after natural sedimentation for 15 min and combined with a microfiltration membrane. This result is caused because Fe(III)–Cr(III) or Al(III)–Cr(III) can form larger SS, which is easily intercepted by the microfiltration membrane. The development of a novel combined method of catalytic chemical reduction and membrane filtration will be beneficial for reducing the retention of TCr in the environment.

Coastal Surveillance and Water Quality monitoring in the Rejiche Sea-Tunisia.

The aim of this study is to determine physiochemical and bacteriological properties of seawater and sediments from the coast of Tunisia during six successive months. The conductivity was measured using previously calibrated Hach Conductivity meter. Total suspended solid was determined using Whatman GF/C glass fiber filter (Sigma Aldrich), and the turbidity was assessed using a spectrophotometer (UV/Vis). The pH was measured using pH electrodes. Other physiochemical parameters were determined using Pastel UV multiparameter water analyzer (Secomam, aqualabo). Bacterial analysis was displayed by membrane filtration method, and isolates were identified to the species level by Api strips. Susceptibility to antibiotics was determined by disk diffusion methods. Total suspended solid, turbidity, adsorbable organic halogen, chemical oxygen demand, and biochemical oxygen demand were higher than accepted norms in Tunisia. Enterococcus faecalis was detected in all the sites indicating a human fecal contamination, and all the isolates were highly resistant to rifampicin, gentamicin, chloramphenicol, ampicillin, and azithromycin. The situation in Mahdia coast is alarming particularly with the isolation of multidrug resistance strains. It is recommended that the local government provide restrict policies for the treatment and the assessment of municipal wastewater before its discharge into sea. PRACTITIONER POINTS: Coastal Surveillance and Water Quality monitoring in the Rejiche Sea - Tunisia is crucial. Enterococcus faecalis was detected in sea water and sediment samples in the coast of Rejiche. Isolated strains were highly resistant to rifampicin, gentamicin, chloramphenicol, ampicillin and azithromycin.

Efficient removal of high-concentration copper ions from wastewater via 2D g-C3N4 photocatalytic membrane filtration

Removal of high-concentration metal ions from wastewater still faces challenges. Since membrane-based technologies have sufficiently proven their effectiveness in removing heavy metals from water, research into the development and application of even more effective membranes is being carried out by researchers around the world. Here, graphitic carbon nitride, g-C3N4, due to its multiple properties, among other things its large specific surface area, its good hydrophilicity, its functional group and above all its photocatalytic capacities made it possible to generate a photocatalytic membrane for the removal of copper ions in water by membrane filtration method. When using the g-C3N4 membrane with thickness of about 310 nm for copper ion wastewater filtration, the efficiency of the light-treated g-C3N4 membrane after 15 h of filtration revealed an average water permeance of 47.82 L m−2 h−1 bar−1 as well as an average rejection rate of 98.03% for the copper ion concentration of 2500 mg/L, which is superior to that of commercial membranes. The g-C3N4 membrane exhibited similar trends in the removal of other heavy metal ions. Three effect have been identified as responsible of high rejection rate of heavy metal ions namely, adsorption due to the functional amino groups of g-C3N4, the effect of electrostatic repulsion and the steric effect. Exposing the membrane to light removed all copper ions present in the water, reducing them to their elemental form. Furthermore, an adsorption-photo reduction-filtration mechanism was proposed for the 2D g-C3N4 membrane to remove copper ions. It therefore opens the way for the use of 2D g-C3N4-based nanomaterials in the field of membrane filtration as photocatalytic membranes for the elimination of heavy metals in wastewater.

EFFECTS OF THE REUSE OF UNTREATED WATER FROM THE AVO’O RIVER (CAMEROON) CONTAMINATED BY FECAL SLUDGE FOR THE GROWTH OF SOLANUM NIGRUM L.

Objective: The main objective of this research was to evaluate the growth parameters and sanitary quality of Solanum nigrum L. irrigated with polluted water from Avo’o river in Nomayos.
 Methods: Faecal sludge, water from Avo’o River and Solanum nigrum L., were analysed with respect to microbiological and parasitological parameters. Four points (S0: Control site, located in Mbankomo at 3 km away from faecal sludge discharge area; S1: located at 810 m before the faecal sludge discharge area; S2: located at 100 m away from the faecal sludge discharge area; and S3: located at 350 m after the faecal sludge discharge area) were considered for sampling events. For faecal indicator (FC: Faecal coliforms and FS: Faecal Streptococci), the membrane filtration method was used. Helminthes eggs were determined using the method of Bailenger, modified by Rodier. The growth parameters of S. nigrum L., measured in different site mentioned above, were plant height, number, length and width of fresh leaves.
 Results: High concentration of FC (6857 ± 5180) and FS (2500 ± 1876 CFU/100 ml), as well as helminths eggs (273 ± 186 eggs/L) were obtained in Avo’o water samples. The strong correlations (r=0.9) clearly show that the waters of the Avo’o stream influence the growth of S. nigrum L.
 Conclusion: Despite the best growth of Solanum Nigrum L. irrigated with water from Avo’o River, high concentration of parasites was obtained on their leaves (43 eggs/100 g) highlight the necessity of a better management of faecal sludge in this city.

Comparative Assessment of Fecal Contamination in Piped-to-Plot Communal Source and Point-of-Drinking Water

The aim of this study was to compare the water quality of piped-to-plot source water with point-of-drinking water in the households of a low-income urban area in Bangladesh. A total of 430 low-income households and 78 communal sources connected to these households were selected from the East Arichpur area of Dhaka. The water samples were collected from point-of-drinking vessels (household members’ preferred drinking vessels i.e., a mug, glass, or bottle) in households and from linked sources at six-week intervals between September 2014 and December 2015. Water samples were processed using standard membrane filtration and culture methods to quantify E. coli. Analysis of paired data from source and point-of-drinking water collected on the same day showed that fecal contamination increased from source to point-of-drinking water in the households in 51% (626/1236) of samples. Comparison between bottles vs. other wide-mouth vessels (i.e., glasses, mugs, jugs) showed significantly lower odds (p = 0.000, OR = 0.58, (0.43–0.78)) of fecal contamination compared to other drinking vessels. The findings suggest that recontamination and post-treatment contamination at the point of drinking play a significant role in water contamination in households. Hygiene education efforts in the future should target the promotion of narrow-mouth drinking vessels to reduce contamination.

Assessment of performance of wastewater stabilization ponds using faecal indicator bacteria reduction efficiency in a tropical environment

Egerton University (EU) uses Wastewater Stabilization Ponds (WSPs) for wastewater treatment. An adjoining wetland with gravel bed substrate and freesurface flow meant to polish discharge before releasing into River Njoro is currently non-operational. The current study aimed at establishing the performance of WSPs in terms of concentration and reduction efficiencies of Faecal Indicator Bacteria (FIB); Total Coliforms (TC) and Escherichia coli (E. coli). Wastewater samples were collected weekly for one month from mid- November to mid-December 2017. Total Coliforms and E. coli were isolated using selective and differential media following Membrane Filtration (MF) method. Colonies were cultured on Chromocult Coliform Agar (CCA) and enumerated using standard procedures for examination of water and wastewater. The results were expressed as Colony Forming Units (CFUs) per 100 ml of the original sample. The inlet showed highest concentration of FIB which reduced along the treatment pathway. Total Coliforms and E. coli ranged between 2.5 × 108 - 2.9 × 1011 and 5.9 × 105 - 1.8 × 1010 CFUs/100 ml respectively with cumulative reduction efficiencies between 2 to 4 log units for E. coli and 2 to 3 log units for TC in the two maturation ponds. Although concentration of FIB in EU WSPs reduces along the treatment pathway, the effluent quality is above recommended international standards for discharge into surface waters. The trend is attributed to lack of frequent monitoring, insufficient maintenance, together with short- circuiting effect due to by-passing of wastewater in the design of the new pond system.

Influence of Sewage Treatment Plant Effluent on the Presence of Culturable Pathogenic Bacteria in the Water Body

The purpose of the sewage treatment process is to decrease the concentration of contaminants, including pathogens, before discharging into the receiving streams. And the standard operating procedure of STP in Malaysia is to discharge the treated wastewater with low nutrient and low organic materials into the streams but the bacterial content of the discharge and its risk to the stream’s natural microbial verity or health is unknown. However, studies reported that pathogens could escape sewage treatment plants (STPs) processes and showed health risk of streams impacted by STP effluent. On the other hand, majority of these studies relied on metagenomic strategy, without assessing changes to culturable bacteria. Isolation of living microbes provides realistic risk assessment compared to metagenome survey alone. Therefore, this study aims to determine the presence of culturable pathogenic bacteria from water impacted by STP effluent to establish justifiable public health risk. For that, the presence of bile resistant bacteria was determined from water taken from surface water receiving effluent from STP-1 (Kolej 9, UTM) in Malaysia. Enumeration and isolation of bacteria were done on MacConkey agar through membrane filtration method, followed by partial identification, using Triple Sugar Iron agar (TSI). The result showed that STP effluent changes the diversity, and abundance, of bile resistant bacteria (specifically Enterobacteriaceae family) of receiving streams. Most of the isolated bile resistant bacteria are opportunistic pathogens for human. Findings from this study provide a snapshot of the bigger picture of microbial changes in a stream impacted by STP effluent painted initially by metagenome studies. And shows that despite of treatment, some contaminants (microbes) remained and released into surface waters, which contribute to the water pollutions.

Evaluation of BACTECTM FX Blood Culture System for Rapid Sterility Testing of Human Medicinal Solutions for Infusion

Human medicinal products for infusion should be tested for sterility at various stages of manufacturing including the final step before marketing. Conventional sterility methods recommended in pharmacopeia need a 14 days incubation period in order to get reliable analytical results. However, rapid alternative methods based on automated detection of microbial growth have the advantage of taking only 5 days for sterility testing of medicinal products which can be very important especially during pandemics and emergency conditions. The aim of the present study is to evaluate the microbial detection potential and capacity of the BACTEC FX system for the rapid sterility testing of Paracerol, a 10 mg/mL paracetamol containing pediatric medicine for infusion, and to specify time required for the detection of a variety of microorganisms. Accordingly, the results showed that there were no significant differences between the BACTEC and conventional membrane filtration methods for detecting contamination. All positive/negative controls and all samples intentionally contaminated with microorganisms were determined correctly by using both methods. BACTEC FX system detected all microorganisms including slow growers significantly faster than the membrane filtration method (p<0.05). This system can be considered as a rapid alternative over conventional sterility methods for the release of human medicinal products for infusion to the markets especially under emergency conditions. However, for each particular products, validation steps should be executed according to European Pharmacopoeia by using a broad range of microorganisms.

Bottled water brands are contaminated with multidrug resistant bacteria in Nairobi, Kenya

Background: The demand for drinking water has necessitated the proliferation of bottled water companies in Kenya. This study evaluated if retailed bottled water in Nairobi Kenya complies with both local and international reference criteria. Methods: A total of 42 different water brands (25 approved by Kenya Revenue Authority (KRA) and 17 banned brands) were analyzed for both physicochemical and bacteriological quality. The spread plate method was used to obtain the total plate count of bacteria, while the membrane filter method was used to obtain total coliform count (TCC) and fecal coliform count (FCC). Structured interviews were used to gather company-related information. Results: Overall, 16% of KRA-approved and 35.3% of banned bottled water were contaminated with heterotrophic bacteria. Of the approved water brands, 4% were positive for total coliforms, compared with 17% of the banned brands. Similarly, 4% and 17% approved and banned water brands were positive for fecal coliforms, respectively. Escherichia coli (19.1%), Pseudomonas spp. (9.5%) and Klebsiella spp. (4.8%) were the most common bacterial types isolated from all water brands, most of which exhibited multidrug resistance. In multivariable analysis, water companies that cleaned pipework and bottles using chlorine-based disinfectants (OR 0.08, 95% CI 0.01 to 0.8), those that had food safety programs (OR 0.1, 95% CI 0.019 to 0.9), had standard operating procedures (SOP) for water sourcing (OR 0.1, 95% CI 0.012 to 0.9) and SOP for contamination protection (OR 0.1, 95% CI 0.02 to 0.9) remained independently associated with bottled water brands exceeding WHO TCC limits. Conclusions: A number of bottled water brands were contaminated with one or more types of indicator bacteria, some of which were multidrug-resistant. Water bottling companies’ processes contribute to contamination. Rigorous regulation and monitoring will improve water quality and safety.

Miniature auto-perfusion bioreactor system with spiral microfluidic cell retention device.

Medium perfusion is critical in maintaining high cell concentration in cultures. The conventional membrane filtration method for medium exchange has been challenged by the fouling and clogging of the membrane filters in long-term cultures. In this study, we present a miniature auto-perfusion system that can be operated inside a common-size laboratory incubator. The system is equipped with a spiral microfluidic chip for cell retention to replace conventional membrane filters, which fundamentally overcomes the clogging and fouling problem. We showed that the system supported continuous perfusion culture of Chinese hamster ovary (CHO) cells in suspension up to 14 days without cell retention chip replacement. Compared to daily manual medium change, 25% higher CHO cell concentration can be maintained at an average auto-perfusion rate of 196 ml/day in spinner flask at 70 ml working volume (2.8 VVD). The auto-perfusion system also resulted in better cell quality at high concentrations, in terms of higher viability, more uniform and regular morphology, and fewer aggregates. We also demonstrated the potential application of the system for culturing mesenchymal stem cells on microcarriers. This miniature auto-perfusion system provides an excellent solution to maintain cell-favorable conditions and high cell concentration in small-scale cultures for research and clinical uses.

Bottled water brands are contaminated with multidrug resistant bacteria in Nairobi, Kenya

Background: The demand for drinking water has necessitated the proliferation of bottled water companies in Kenya. This study evaluated if retailed bottled water in Nairobi Kenya complies with both local and international reference criteria. Methods: A total of 42 different water brands (25 approved by Kenya Revenue Authority (KRA) and 17 banned brands) were analyzed for both physicochemical and bacteriological quality. The spread plate method was used to obtain the total plate count of bacteria, while the membrane filter method was used to obtain total coliform count (TCC) and fecal coliform count (FCC). Structured interviews were used to gather company-related information. Results: Overall, 16% of KRA-approved and 35.3% of banned bottled water were contaminated with heterotrophic bacteria. Of the approved water brands, 4% were positive for total coliforms, compared with 17% of the banned brands. Similarly, 4% and 17% approved and banned water brands were positive for fecal coliforms, respectively. Escherichia coli (19.1%), Pseudomonas spp. (9.5%) and Klebsiella spp. (4.8%) were the most common bacterial types isolated from all water brands, most of which exhibited multidrug resistance. In multivariable analysis, water companies that cleaned pipework and bottles using chlorine-based disinfectants (OR 0.08, 95% CI 0.01 to 0.8), those that had food safety programs (OR 0.1, 95% CI 0.019 to 0.9), had standard operating procedures (SOP) for water sourcing (OR 0.1, 95% CI 0.012 to 0.9) and SOP for contamination protection (OR 0.1, 95% CI 0.02 to 0.9) remained independently associated with bottled water brands exceeding WHO TCC limits. Conclusions: A number of bottled water brands were contaminated with one or more types of indicator bacteria, some of which were multidrug-resistant. Water bottling companies’ processes contribute to contamination. Rigorous regulation and monitoring will improve water quality and safety.

Detection Of Fecal Coliforms In Water Used In Formal And Informal Food Outlets In Kasungu District, Malawi

Poor sanitary practices are common amongst many food handlers posing a health risk to consumers. Maintenance of high quality water is one of the most important aspects of ensuring consumer safety. Therefore, regular water testing is critical in public food outlets where bacterial contamination may cause outbreak of disease. The study aimed at analyzing water samples obtained from the formal and informal food outlets for the presence of fecal coliforms that are indicative of poor sanitation that result in foodborne infections amongst consumers. Using a cross-sectional design, water samples from participating food outlets (N=40) were analyzed using the membrane filtration method. Samples were filtered, under vacuum, through a cellulose acetate membrane of 0.45 μm pore size. Fecal coliforms exceeding permissible range were detected in 15 test samples (N=40). The median (IQR) concentrations of fecal coliforms (FC/100ml) in dishwashing water was 1(136) and 145(340) for the formal and informal food outlets respectively. The median (IQR) for drinking water was 0(0) with a minimum and maximum range of 0 and 14 FC/100mls. The study established a positive correlation between fecal coliforms and electrical conductivity, and total dissolved solids (p&lt;0.05) in dish washing water used at both formal and informal food outlets. Contamination was attributed to lack of running water, poor pest control and unwholesome practices in many food outlets. Based on the study findings, it is concluded that electrical conductivity, total dissolved solids and turbidity values may be used to deduce the presence of fecal coliforms in water. The study recommends that water drawn from unprotected sources must be boiled or treated at the point of use before it can be safely used in food outlets. Periodic water testing and sanitary supervisions for all food outlets must be mandatory to ensure compliance with minimum set standards.

CALIDAD DEL AGUA SUBTERRÁNEA EN UNA ZONA KÁRSTICA DE LA ISLA DE COZUMEL, QUINTANA ROO, MÉXICO (Español) ; GROUNDWATER QUALITY IN A KARSTIC ZONE OF THE ISLAND OF COZUMEL, QUINTANA ROO, MÉXICO

&lt;p&gt;&lt;strong&gt;Background. &lt;/strong&gt;In the Yucatan peninsula, the main source of water supply for all human activities is groundwater; however, it is highly vulnerable to pollution due to the characteristics of the karst aquifer, which allow a direct and a very susceptible infiltration to pollutant transport. The same process occurs in the islands systems of the east side of the peninsula, particularly on the islands of Holbox, Isla Mujeres and Cozumel, the latter being the most populated (almost 100 000 inhabitants) and with the existence of irregular settlements in the protection areas and water abstraction.&lt;strong&gt; Objective. &lt;/strong&gt;In order to understand the characteristics of the groundwater quality, the aim of this study is to sample, determine and map the spatial and temporal behavior of water as a resource, as well as to determine if there are significant differences among the sampling seasons.&lt;strong&gt; Methodology. &lt;/strong&gt;To be able to do so, the sampling sites were determined under the following premises: the number of people residing in the plot of land, the years that people have resided in the settlement, if they own an extraction well for domestic use, if they possess a water extraction pump, if they have no drainage, if they burn their garbage and if they have ever become ill from using the extracted water for bathing. Regarding the physical and chemical parameters (temperature, pH, salinity and TDS) they were analyzed &lt;em&gt;in situ&lt;/em&gt; with multi-parametric instruments; while the bacteriological study was measured by means of the Millipore ® membrane filtration method and chloride were completed in the laboratory; the samplings correspond to three periods (rainy, “Nortes” and dry seasons). The shaping of the spatial pattern of distribution for each parameter was developed using IDW interpolation.&lt;strong&gt; &lt;/strong&gt;Finally, the statistical analysis was conducted with the one-way ANOVA statistical test, as well as the post hoc test for those parameters that had significant differences&lt;strong&gt; Results. &lt;/strong&gt;Thus, eight sampling sites were selected taking into consideration the representative distribution of the territory (132 wells were recognized). In addition, the results tables of the parameters for the rainy, “Nortes” and dry seasons are presented in this document, as well as the maps of spatial distribution. &lt;strong&gt;Implications. &lt;/strong&gt;The main limitation to carry out this research was the prohibition when taking two samples, since, for different circumstances, we were not allowed to sample in one sector of the study area.&lt;strong&gt; Conclusion. &lt;/strong&gt;From the results of the physicochemical and bacteriological analyzes it is concluded that the water extracted from the wells is not suitable for human use and consumption, since the levels of total dissolved solids and fecal coliforms exceed the maximum permissible limits of the NOM-127-SSA1-1994.&lt;/p&gt;