Roman Tandlich

Anaerobic digestion of fungally pre-treated wine distillery wastewater

The combination of fungal pre-treatment with Trametes pubescens and anaerobic digestion were tested for the removal of chemical oxygen demand (COD) and phenolic compounds from wine distillery wastewater. The COD removal efficiency after fungal pre-treatment reached 53.3%. During digestion, pH buffering was achieved using CaCO3 and K2HPO4. This provided a stable environment inside digester for efficient and time-independent COD removal. The total COD removal efficiency reached 99.5%, and the system proved able to eliminate shock COD loads, as indicated by the concentrations of sludge and volatile fatty acids. Complex changes of phenolic compounds are suspected in anaerobic digestion system, and are investigated further.

Sorption of hydrophobic organic compounds on natural sorbents and organoclays from aqueous and non-aqueous solutions: a mini-review.

Renewed focus on the sorption of hydrophobic organic chemicals (HOCs) onto mineral surfaces and soil components is required due to the increased and wider range of organic pollutants being released into the environment. This mini-review examines the possibility of the contribution and mechanism of HOC sorption onto clay mineral sorbents such as kaolinite, and soil organic matter and the possible role of both in the prevention of environmental contamination by HOCs. Literature data indicates that certain siloxane surfaces can be hydrophobic. Therefore soils can retain HOCs even at low soil organic levels and the extent will depend on the structure of the pollutant and the type and concentration of clay minerals in the sorbent. Clay minerals are wettable by nonpolar solvents and so sorption of HOCs onto them from aqueous and non-aqueous solutions is possible. This is important for two reasons: firstly, the movement and remediation of soil environments will be a function of the concentration and type of clay minerals in the soil. Secondly, low-cost sorbents such as kaolinite and expandable clays can be added to soils or contaminated environments as temporary retention barriers for HOCs. Inorganic cations sorbed onto the kaolinite have a strong influence on the rate and extent of sorption of hydrophobic organic pollutants onto kaolinite. Structural sorbate classes that can be retained by the kaolinite matrix are limited by hydrogen bonding between hydroxyl groups of the octahedral alumosilicate sheet and the tetrahedral sheet with silicon. Soil organic carbon plays a key role in the sorption of HOCs onto soils, but the extent will be strongly affected by the structure of the organic soil matter and the presence of soot. Structural characterisation of soil organic matter in a particular soil should be conducted during a particular contamination event. Contamination by mining extractants and antibiotics will require renewed focus on the use of the QSAR approaches in the context of the sorption of HOCs onto clay minerals from aqueous and non-aqueous solutions.

Microbial Monitoring of Surface Water in South Africa: An Overview

Infrastructural problems force South African households to supplement their drinking water consumption from water resources of inadequate microbial quality. Microbial water quality monitoring is currently based on the Colilert®18 system which leads to rapidly available results. Using Escherichia coli as the indicator microorganism limits the influence of environmental sources on the reported results. The current system allows for understanding of long-term trends of microbial surface water quality and the related public health risks. However, rates of false positive for the Colilert®18-derived concentrations have been reported to range from 7.4% to 36.4%. At the same time, rates of false negative results vary from 3.5% to 12.5%; and the Colilert medium has been reported to provide for cultivation of only 56.8% of relevant strains. Identification of unknown sources of faecal contamination is not currently feasible. Based on literature review, calibration of the antibiotic-resistance spectra of Escherichia coli or the bifidobacterial tracking ratio should be investigated locally for potential implementation into the existing monitoring system. The current system could be too costly to implement in certain areas of South Africa where the modified H2S strip test might be used as a surrogate for the Colilert®18.

Application of Liquid Membranes in Wastewater Treatment

Publisher Summary This chapter discusses significant and potential applications in wastewater treatment. Wastewater treatment methods include physical processes, for example, adsorption, and sand filtration, chemical processes, for example, flocculation by addition of aluminum salts, iron salts, and polymeric substances and biological processes, for example, the activated sludge process and anaerobic digestion. These processes are efficient and can provide water that meets different regulatory requirements. However, problems are encountered if toxic levels of different organic compounds and/or heavy metals are present in wastewater. This can lead to the breakdown of treatment performance, for example, in biological processes. Liquid membrane (LM) processes take advantage of the already established principles of biological treatment and solvent extraction but provide the advantage of reduction in treatment costs. Therefore, a wide variety of the flat-sheet supported liquid membrane (SLM) systems are used. The advantages of the flat-sheet SLM arrangement in the removal of organic compounds from wastewater can be achieved, if low-cost extractants/diluents, such as vegetable oils, are used. However, the energy considerations will probably lead to the preferential application of hollow-fiber SLM systems in the industry. On the basis of the laboratory study results, the SLM technology provides an ideal tool for the removal of trace amounts of the antibiotics, and potentially even other pharmaceutical products, from wastewaters. This will prevent the exposure of the MOs in the environment to antibiotics, thus eliminating the potential for the selection of microbial strains resistant to the respective antibiotic(s).

Survival of Bifidobacteria and their usefulnessin Faecal Source Tracking

Abstract: Bifidobacteria have long since been recommended as indicators of human and animal pollution. Concentration ratio (tracking ratio) of the sorbitol-utilising bifidobacteria (SUB) and the total bifidobacteria (TB) can be used to distinguish between animal and human sources of faecal water contamination. The cut-off value needs to be calibrated in a given geographical area. Seven sites with permanent faecal contamination were selected in South Africa. Concentrations of SUB ranged from 10-50000 cells/100 mL, while TB ranged from 0-8000 cells/100 mL. The tracking ratio ranged from 0.10 to 6.25, but no clear cut-off value could be established. The YN-17 agar was replaced for TB with the modified Beerens medium with pH = 5.70, to suppress the growth of faecal streptococci. Tracking ratios observed are most likely the results of different survival rates of SUB and TB. Bifidobacteria die-off due to nutrients was not found to be significant using design of experiment. Thus a lack of continuous input or oxygen levels in water may be major factors. This would limit the ratios used as a faecal source tracking method.

Antibiotic-Resistant Pathogenic Escherichia Coli Isolated from Rooftop Rainwater-Harvesting Tanks in the Eastern Cape, South Africa

Although many developing countries use harvested rainwater (HRW) for drinking and other household purposes, its quality is seldom monitored. Continuous assessment of the microbial quality of HRW would ensure the safety of users of such water. The current study investigated the prevalence of pathogenic Escherichia coli strains and their antimicrobial resistance patterns in HRW tanks in the Eastern Cape, South Africa. Rainwater samples were collected weekly between June and September 2016 from 11 tanks in various areas of the province. Enumeration of E. coli was performed using the Colilert®18/Quanti-Tray® 2000 method. E. coli isolates were obtained and screened for their virulence potentials using polymerase chain reaction (PCR), and subsequently tested for antibiotic resistance using the disc-diffusion method against 11 antibiotics. The pathotype most detected was the neonatal meningitis E. coli (NMEC) (ibeA 28%) while pathotype enteroaggregative E. coli (EAEC) was not detected. The highest resistance of the E. coli isolates was observed against Cephalothin (76%). All tested pathotypes were susceptible to Gentamicin, and 52% demonstrated multiple-antibiotic resistance (MAR). The results of the current study are of public health concern since the use of untreated harvested rainwater for potable purposes may pose a risk of transmission of pathogenic and antimicrobial-resistant E. coli.

Adsorptive removal of ciprofloxacin and isoniazid from aqueous solution

Abstract This paper describes study of ciprofloxacin and isoniazid removal from aqueous solutions using coal fly ash (FA), kaolinite, perlite, talc and vermiculite. The adsorptive features of the adsorbents were evaluated for ciprofloxacin and isoniazid with regards to the effects of contact time, pH, the solid/liquid ratio and antibiotic concentration. All adsorbents were sterilised by dry heat before use to avoid the proliferation of antimicrobial resistance by the bacteria present on the adsorbents during experiments. The regression correlation coefficients indicate that the Langmuir model gives the best fit for the sorption of both antibiotics onto FA and talc, ciprofloxacin onto kaolinite, and isoniazid onto perlite and vermiculite with R2 values ranging from 0.908 – 0.999. The Freundlich isotherm best describes the sorption of ciprofloxacin onto vermiculite and isoniazid onto kaolinite with R2 values of 0.999 for both. The Tempkin model best describes the sorption of ciprofloxacin onto perlite with an R2 = 0.997. The values of the Freundlich exponent, 1/n, range from 0.221 – 0.998, indicating a favourable adsorption of ciprofloxacin and isoniazid onto the adsorbents. The heat of sorption, B, calculated from the Temkin plots has values ranging from 0.018 – 10.460 J/mol, indicating a physical adsorption process (physisorption). Adsorption equilibrium was achieved after 30 min for both antibiotics and the kinetic data obtained conforms best to the pseudo-second order equation with R2 values ranging from 0.998 – 0.999. The removal of ciprofloxacin and isoniazid by all adsorbents except FA was strongly influenced by the pH suggesting that electrostatic interactions play a major role in the adsorption processes.

Radioactive Waste Management in South Africa

South Africa’s electricity consumption has been marked with a rapid surge ever since 1980, which makes the government appeal to nuclear power as a potential solution.

Optimisation of the emulsion liquid membrane composition and demulsification for rhodium extraction

Abstract: This study was aimed at designing an optimised emulsion liquid membrane (ELM) for the extraction of rhodium from precious metal refinery wastewaters. The demulsification process and the structure of the optimised ELM are reported on. Two optimised ELMs were prepared. The first one contained a 30 % solution of toluene in kerosene as diluent with the following concentrations of the ELM components: 30.000 g/L (w/v) polyisobutylene, 10.870 g/L (m/v) of trioctyl amine and 51.001 g/L (m/v) of SPAN 80. The second ELM contained the same diluent, but the concentrations of the other ELM components in it were as follows: 20.000 g/l of polyisobutylene, 10.268 g/l trioctyl amine and 50.024 g/l of SPAN 80. The stripping phase was the same in both optimised ELMs, namely a 2 M solution of HNO3. The stripping phase and the diluent solution were mixed together in ratios of 1:1 and 2:1, respectively. Two methods were used to characterise the microdroplet diameters, i.e. optical microscopy and the Zeta-sizer. For the t-test, the p-value of 0.3018 at 5 % level of significance showed that there was statistically no significant difference in the mean micro-droplet size for 1:2 ELMs containing 20 g/l and 30 g/l of polyisobutylene after 40 minutes of emulsification. The best demulsification results were obtained using the chemical demulsification with polyethylene glycol with molecular weight of 400 g/mol (PEG 400) at 50 ± 1 °C for 24 hours. However, significant carryover of toluene, trioctyl amine and polyethylene glycol into the aqueous phase was observed.