Cost-Effective Filter Materials Coated with Silver Nanoparticles for the Removal of Pathogenic Bacteria in Groundwater

The contamination of groundwater sources by pathogenic bacteria poses a public health concern to communities who depend totally on this water supply. In the present study, potentially low-cost filter materials coated with silver nanoparticles were developed for the disinfection of groundwater. Silver nanoparticles were deposited on zeolite, sand, fibreglass, anion and cation resin substrates in various concentrations (0.01 mM, 0.03 mM, 0.05 mM and 0.1 mM) of AgNO3. These substrates were characterised by SEM, EDS, TEM, particle size distribution and XRD analyses. In the first phase, the five substrates coated with various concentrations of AgNO3 were tested against E. coli spiked in synthetic water to determine the best loading concentration that could remove pathogenic bacteria completely from test water. The results revealed that all filters were able to decrease the concentration of E. coli from synthetic water, with a higher removal efficiency achieved at 0.1 mM (21–100%) and a lower efficiency at 0.01 mM (7–50%) concentrations. The cation resin-silver nanoparticle filter was found to remove this pathogenic bacterium at the highest rate, namely 100%. In the second phase, only the best performing concentration of 0.1 mM was considered and tested against presumptive E. coli, S. typhimurium, S. dysenteriae and V. cholerae from groundwater. The results revealed the highest bacteria removal efficiency by the Ag/cation resin filter with complete (100%) removal of all targeted bacteria and the lowest by the Ag/zeolite filter with an 8% to 67% removal rate. This study therefore suggests that the filter system with Ag/cation resin substrate can be used as a potential alternative cost-effective filter for the disinfection of groundwater and production of safe drinking water

Cost-Effective Filter Materials Coated with Silver Nanoparticles for the Removal of Pathogenic Bacteria in Groundwater

The contamination of groundwater sources by pathogenic bacteria poses a public health concern to communities who depend totally on this water supply. In the present study, potentially low-cost filter materials coated with silver nanoparticles were developed for the disinfection of groundwater. Silver nanoparticles were deposited on zeolite, sand, fibreglass, anion and cation resin substrates in various concentrations (0.01 mM, 0.03 mM, 0.05 mM and 0.1 mM) of AgNO3. These substrates were characterised by SEM, EDS, TEM, particle size distribution and XRD analyses. In the first phase, the five substrates coated with various concentrations of AgNO3 were tested against E. coli spiked in synthetic water to determine the best loading concentration that could remove pathogenic bacteria completely from test water. The results revealed that all filters were able to decrease the concentration of E. coli from synthetic water, with a higher removal efficiency achieved at 0.1 mM (21–100%) and a lower efficiency at 0.01 mM (7–50%) concentrations. The cation resin-silver nanoparticle filter was found to remove this pathogenic bacterium at the highest rate, namely 100%. In the second phase, only the best performing concentration of 0.1 mM was considered and tested against presumptive E. coli, S. typhimurium, S. dysenteriae and V. cholerae from groundwater. The results revealed the highest bacteria removal efficiency by the Ag/cation resin filter with complete (100%) removal of all targeted bacteria and the lowest by the Ag/zeolite filter with an 8% to 67% removal rate. This study therefore suggests that the filter system with Ag/cation resin substrate can be used as a potential alternative cost-effective filter for the disinfection of groundwater and production of safe drinking water

Pollution of Sand River by Wastewater Treatment Works in the Bushbuckridge Local Municipality, South Africa

Pollution of water sources is a global issue that primarily affects rural communities that rely on these water sources for domestic purposes on a daily basis. The study’s goal was to determine if the effluent from the Bushbuckridge Municipality’s Waste Water Treatment Works (WWTWs) contributes to the pollution of the Sand River Catchment. The investigation was conducted at two WWTWs, Dwarsloop and Thulamahashe. A questionnaire was used to collect information from participants. Water samples were collected monthly from the treatment plant and Sand River for the determination of physico-chemical parameters and coliform counts. The study found that the WWTWs were the main sources of the pollution of the Sand River Catchment. The WWTWs are confronting unprecedented mechanical and technical challenges. The WWTWs have experienced numerous system failures due to aging systems and pressure on deteriorating facilities, resulting in raw wastewater discharges into catchments. Furthermore, the study revealed that factors such as population growth, poor operation and maintenance of WWTWs, poor budgeting, and a lack of well-trained personnel contributed to WWTW failure. The effluent quality in both WWTWs met the National Water Act of South Africa’s effluent discharge standards for pH (ranged from 6.90 to 9.30), EC (ranged from 20.80 to 87.50 mS/m), ammonia (ranged from 7.22 to 86.80 mg/L as N), nitrate/nitrite (ranged from 0.10 to 0.73 mg/L as N), and ortho-phosphate (ranged from 0.01 to 6.50 mg/L as P). While COD levels in both WWTWs (ranging from 25.00 to 149.00 mg/L) were over the limit during some months of the study period. The study also discovered that E. coli counts were low upstream but high in both the WWTWs point of discharge and downstream for both catchments. The study, therefore, established a connection between wastewater treatment plants and water quality parameters as well as poor water quality linked to the condition of the WWTWs. The study recommends that effective measures be implemented to address the challenges

Pollution of Sand River by Wastewater Treatment Works in the Bushbuckridge Local Municipality, South Africa

Pollution of water sources is a global issue that primarily affects rural communities that rely on these water sources for domestic purposes on a daily basis. The study’s goal was to determine if the effluent from the Bushbuckridge Municipality’s Waste Water Treatment Works (WWTWs) contributes to the pollution of the Sand River Catchment. The investigation was conducted at two WWTWs, Dwarsloop and Thulamahashe. A questionnaire was used to collect information from participants. Water samples were collected monthly from the treatment plant and Sand River for the determination of physico-chemical parameters and coliform counts. The study found that the WWTWs were the main sources of the pollution of the Sand River Catchment. The WWTWs are confronting unprecedented mechanical and technical challenges. The WWTWs have experienced numerous system failures due to aging systems and pressure on deteriorating facilities, resulting in raw wastewater discharges into catchments. Furthermore, the study revealed that factors such as population growth, poor operation and maintenance of WWTWs, poor budgeting, and a lack of well-trained personnel contributed to WWTW failure. The effluent quality in both WWTWs met the National Water Act of South Africa’s effluent discharge standards for pH (ranged from 6.90 to 9.30), EC (ranged from 20.80 to 87.50 mS/m), ammonia (ranged from 7.22 to 86.80 mg/L as N), nitrate/nitrite (ranged from 0.10 to 0.73 mg/L as N), and ortho-phosphate (ranged from 0.01 to 6.50 mg/L as P). While COD levels in both WWTWs (ranging from 25.00 to 149.00 mg/L) were over the limit during some months of the study period. The study also discovered that E. coli counts were low upstream but high in both the WWTWs point of discharge and downstream for both catchments. The study, therefore, established a connection between wastewater treatment plants and water quality parameters as well as poor water quality linked to the condition of the WWTWs. The study recommends that effective measures be implemented to address the challenges

Chemical phosphate removal from Hartbeespoort Dam water, South Africa

Phosphate is one of the major nutrients contributing to the increased eutrophication of lakes and natural waters. The feed water to the Hartbeespoort Dam amounts to 650 ML/d of mainly treated sewage.  Phosphate levels in the dam water need to be lowered from the current 0.2 mg/L to less than 0.05 mg/L to control eutrophication.  Chemicals such as iron(III), iron(II), aluminium(III) and lime can be used to precipitate phosphate as FePO4, Fe3(PO4)2, AlPO4 and Ca3(PO4)2, respectively. OLI software was used to identify the most suitable chemical for phosphate removal. It was found to be Ca(OH)2 as this only requires the pH to be raised to 9.5. FeCl3, FeCl2 and AlCl3 were found to be unsuitable due to the required pH and/or the extent to which they could remove phosphate. For lowering of phosphate levels from 0.2 mg/L (as P), the current concentration in the Hartbeespoort Dam water, to <0.05 mg/L (as P), the minimum concentration that is needed to support algal growth, a lime dosage of 50 mg/L  is required. The cost of lime treatment will amount to 0.15 ZAR/m3. It is thus recommended that eutrophication in the Hartbeespoort Dam be controlled by removal of phosphate through lime dosing

Dramatic Reduction in Diarrhoeal Diseases through Implementation of Cost-Effective Household Drinking Water Treatment Systems in Makwane Village, Limpopo Province, South Africa

The main purpose of this study was to implement cost-effective household water treatment systems in every household of Makwane Village for the reduction of diarrhoeal diseases. These household water treatment systems were constructed with locally available materials and consisted of the biosand zeolite-silver impregnated granular clay filters and the silver-impregnated porous pot filters. During the study period (April 2015 to September 2015), the entire village had 88 households with a population size of 480. Prior to the implementation, a survey was conducted and results revealed that 75% (360/480) of the Makwane residents suffered from diarrhoeal disease and the majority of the cases were reported in children that were less than five years of age. Out of the 480 participants, 372 (77.5%) from 70 households accepted the installation of the systems (intervention group) and 108 (25.5%) from 18 households were reluctant to use the systems (the control group). To date, in the intervention group, only 3.8% (14/372) of participants reported cases of diarrhoea. In the control group, 57.4% (62/108) participants reported cases of diarrhoea and most of the episodes of diarrhoea were reported in children of less than five years old (85%), followed by the group aged ≥56 years (75%). The findings of the current study unequivocally demonstrated that the BSZ-SICG and SIPP filters were able to reduce the incidence of diarrhoea by 96.2%. These findings further demonstrate the importance of household water treatment systems (HWTS) interventions in rural areas to bring about meaningful reductions in diarrhoeal diseases by providing safe potable water

Assessment of Pharmaceuticals, Personal Care Products, and Hormones in Wastewater Treatment Plants Receiving Inflows from Health Facilities in North West Province, South Africa

The presence of 17 pharmaceutical and personal care products (PPCPs) belonging to various therapeutic categories was investigated in two hospital wastewater treatment plants (WWTPs) in North West Province, South Africa. The compounds were extracted from wastewater samples by solid-phase extraction and analysed by liquid chromatography-tandem mass spectrometry. The results showed that ofloxacin, chloramphenicol, and bezafibrate were generally below the limit of quantification (LOQ) in the analysed samples. Acetaminophen and ibuprofen were the dominant pharmaceuticals in the influent streams with corresponding concentrations ranging from 21 to 119 μg/L and 0.3 to 63 μg/L, respectively. Both WWTPs were shown to have the capability to remove some of the target PPCPs, including acetaminophen (76-98%), tetracycline (15-93%), ibuprofen (44-99%), and triclocarban (13-98%). The monitoring of the target PPCPs in both influent and effluent samples of the investigated WWTPs revealed that the discharge of inadequately treated effluents could be contributing to the possible increase in the concentrations of these contaminants in the receiving environmental compartments. Further studies must be focused on the broader characterisation of these matrices in order to assess the potential ecological impacts of this waste disposal practice

Inhibition of biofilm formation on the surface of water storage containers using biosand zeolite silver-impregnated clay granular and silver impregnated porous pot filtration systems.

Development of biofilms occurring on the inner surface of storage vessels offers a suitable medium for the growth of microorganisms and consequently contributes to the deterioration of treated drinking water quality in homes. The aim of this study was to determine whether the two point-of-use technologies (biosand zeolite silver-impregnated clay granular (BSZ-SICG) filter and silver-impregnated porous pot (SIPP) filter) deployed in a rural community of South Africa could inhibit the formation of biofilm on the surface of plastic-based containers generally used by rural households for the storage of their drinking water. Culture-based methods and molecular techniques were used to detect the indicator bacteria (Total coliforms, faecal coliform, E. coli) and pathogenic bacteria (Salmonella spp., Shigella spp. and Vibrio cholerae) in intake water and on the surface of storage vessels containing treated water. Scanning electron microscopy was also used to visualize the development of biofilm. Results revealed that the surface water source used by the Makwane community was heavily contaminated and harboured unacceptably high counts of bacteria (heterotrophic plate count: 4.4-4.3 Log10 CFU/100mL, total coliforms: 2.2 Log10 CFU/100 mL-2.1 Log10 CFU/100 mL, faecal coliforms: 1.9 Log10 CFU/100 mL-1.8 Log10 CFU/100 mL, E. coli: 1.7 Log10 CFU/100 mL-1.6 Log10 CFU/100 mL, Salmonella spp.: 3 Log10 CFU/100 mL -8 CFU/100 mL; Shigella spp. and Vibrio cholerae had 1.0 Log10 CFU/100 mL and 0.8 Log10 CFU/100 mL respectively). Biofilm formation was apparent on the surface of the storage containers with untreated water within 24 h. The silver nanoparticles embedded in the clay of the filtration systems provided an effective barrier for the inhibition of biofilm formation on the surface of household water storage containers. Biofilm formation occurred on the surface of storage plastic vessels containing drinking water treated with the SIPP filter between 14 and 21 days, and on those containing drinking water treated with the BSZ-SICG filter between 3 and 14 days. The attachment of target bacteria on the surface of the coupons inoculated in storage containers ranged from (0.07 CFU/cm2-227.8 CFU/cm2). To effectively prevent the development of biofilms on the surface of container-stored water, which can lead to the recontamination of treated water, plastic storage containers should be washed within 14 days for water treated with the SIPP filter and within 3 days for water treated with the BSZ-SICG filter