Novel bio-catalytic degradation of endocrine disrupting compounds in wastewater

DATA AVAILABILITY STATEMENT : The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.Against the backdrop of towering ecological health implications of estrogen pollution and the inefficacies associated with cost-intensive treatment techniques, this study recorded the earliest attempt of developing an inexpensive bacterial laccase-based biocatalysts for biodegradation of EDCs (Endocrine disrupting compounds), particularly estrogens. First, a central composite design was used to investigate the interactive effects of pH (6.0–8.0), inoculum size (100–500 U/mL), and copper (Cu) (25–75 mg/L) on laccase activity and estrogen degradation respectively. Thereafter, biocatalysts was synthesized comprising laccase and glass beads or silver impregnated clay granules (SICG), which was further used to treat estrogen infused aquatic matrices under different reaction conditions. Maximum laccase activities and estrogen removal for the two tested laccases were 620 U/mL (85.8–92.9%) and 689.8 U/mL (86.8–94.6%) for Lysinibacillus sp. BP1 and Lysinibacillus sp. BP2, respectively, within 72 h, under conditions of optimal inoculum size and/or Cu concentration. Apart from a higher estrogen removal rate compared to free laccased, the biocatalysts were more resistant to temperature, pH and other environmental perturbations, and had enhanced storage ability and reusability. In comparison to clay, beads had a higher potential for recyclability and were more stable under certain experimental factors such as pH, reuse, and temperature, as well as storage conditions. Immobilized enzymes were able to remove 100% of E2, as well as over 90% of E1 and EE2, in 24 h, indicating that they could be scaled up to benchtop bioreactor levels.NRF SARChI Chair for Water Quality and Wastewater Management and Tshwane University of Technology (TUT).http://www.frontiersin.org/Bioengineering_and_Biotechnologyam2023Chemical Engineerin

Assessing the Sustainability and Acceptance Rate of Cost-Effective Household Water Treatment Systems in Rural Communities of Makwane Village, South Africa

The current study investigated the acceptance rate and long-term effectiveness of cost-effective household water treatment systems deployed in Makwane Village. A structured questionnaire was used prior to implementation to collect information such as level of education, level of employment, and knowledge about point-of-use water treatment systems in the target area. The long-term effectiveness was determined by factors such as the Escherichia coli removal efficiency, turbidity reduction, silver leached, and flow rate of the household water treatment devices. The results of the survey prior to deployment revealed that only 4.3% of the community had a tertiary qualification. Moreover, 54.3% of the community were unemployed. The results further revealed that 65.9% of the community were knowledgeable about other point-of-use water treatment methods. The acceptance rate, which was found to be initially higher (100%), reduced after three months of implantation (biosand filter with zeolite-silver clay granular—82.9%; silver-impregnated porous pot filters—97.1%). Moreover, the long-term effectiveness was determined, taking into consideration the adoption rate, and it was found that silver-impregnated porous pot filters have a long life compared to biosand filter with zeolite-silver clay granular. Although household water treatment systems can effectively reduce the burden of waterborne diseases in impoverished communities, the success of adoption is dependent on the targeted group. This study highlights the significance of involving community members when making the decision to scale up household water treatment devices in rural areas for successful adoption

An Integrated Approach to Hygiene, Sanitation, and Storage Practices for Improving Microbial Quality of Drinking Water Treated at Point of Use: A Case Study in Makwane Village, South Africa

This study assessed the impact of sanitation practices, hygienic and storage conditions on the quality of drinking water treated at point-of-use in Makwane Village. Subsequent to implementation of low-cost Household Water Treatment Devices which are the biosand filter with zeolite-silver (BSZ-SICG) and silver-impregnated porous pot (SIPP) filters in Makwane village, a structured questionnaire was designed to collect the following information: age of caretakers, number of children under the age of five, water storage conditions, sanitation amenities, and hygiene practices. Water quality from the sources to household level was assessed using culture-based and molecular techniques. The results revealed a significant association between the presence of Escherichia coli in treated drinking water with the age group of caregivers and the number of children ofless than the age of five [OR (95% CI) = 8.4737 (0.147–3.3497), p = 0.0141923 and OR (95% CI) = 9.1667 (0.1848–3.0159); p = 0.0165830, respectively]. Moreover, significant association was noted between hygiene practices (washing of hands with/without soap) and water quality in storage containers [OR (95% CI) = 16.000 (0.6763–3.9495), p = 0.0000125]. These findings further prove that there is still a dire need for reconsidering hygiene education in rural areas as the health benefits of water treated at point of use (POU) coupled with safe-storage condition interventions might not be guaranteed without proper hygiene. The results further highlighted the importance of washing hands in improving microbial quality of drinking water, which is the key factor for fighting against infectious diseases

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

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

Schematic representation of the SIPP filter—A: silver-impregnated porous pot; B: 10 L bucket with clay pot inside; C: 20 L bucket for the collection of treated water; D: a complete SIPP filter.

<p>Schematic representation of the SIPP filter—A: silver-impregnated porous pot; B: 10 L bucket with clay pot inside; C: 20 L bucket for the collection of treated water; D: a complete SIPP filter.</p

Average physicochemical analysis values of untreated and treated water samples (D = days).

<p>Average physicochemical analysis values of untreated and treated water samples (D = days).</p

Oligonucleotides used in this study for amplification of pathogenic genes of <i>E</i>. <i>coli</i> strains [30].

<p>Oligonucleotides used in this study for amplification of pathogenic genes of <i>E</i>. <i>coli</i> strains [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194715#pone.0194715.ref030" target="_blank">30</a>].</p

Schematic representation of modified HWTS—(1) BSZ-SICG; (2) modified BSF with zeolite and silver-impregnated granular clay; (3) layers of the modified BSF (A—7 mm gravel; B—0.95 mm coarse sand; C—3 mm natural zeolite; D—silver-impregnated granular clay; E—diffusion plate; and F—0.15 mm fine sand); (4) a complete BSZ-SICG.

<p>Schematic representation of modified HWTS—(1) BSZ-SICG; (2) modified BSF with zeolite and silver-impregnated granular clay; (3) layers of the modified BSF (A—7 mm gravel; B—0.95 mm coarse sand; C—3 mm natural zeolite; D—silver-impregnated granular clay; E—diffusion plate; and F—0.15 mm fine sand); (4) a complete BSZ-SICG.</p

SEM images depicting attachment of microorganisms on the surface of coupons inoculated in treated water produced by BSZ-SICG system (after washing the storage container and re-suspension of new coupons, with a residual silver concentration of 0.045 mg/L).

<p>SEM images depicting attachment of microorganisms on the surface of coupons inoculated in treated water produced by BSZ-SICG system (after washing the storage container and re-suspension of new coupons, with a residual silver concentration of 0.045 mg/L).</p