Study of potential PCR inhibitors in drinking water for Escherichia coli identification

ArticleIn the last few decades, the polymerase chain reaction (PCR) has become one of the most powerful molecular biological tools. However, the PCR is an enzymatic reaction and therefore sensitive to inhibitors which may occur in drinking water samples. In this work, the possible inhibition effect of chlorine, humic acids, and iron for real - time PCR (qPCR) efficiency was studied and the environmental sample from drinking water treatment system before iron removal was selected and analysed. The results demonstrate d that the highest concentrations of humic acids (5 mg L - 1 and 1 mg L - 1 ) and iron (4 mg L - 1 ) inhibited the PCR reaction while no effect of chlorine was observed. The analysis of the environmental sample with spiked Escherichia coli cells demonstrated reduc tion efficiency of the average threshold cycle (C t ) values compared with control dilution series determining the possible inhibition for qPCR assay

Extended use of Sphagnum peat as a biosorbent for Zn(II): repetiti ous sorption-desorption process

ArticleIn this study, continuous biosorption - desorption cycles in a fixed - bed column were performed to evaluate the extended use of sphagnum peat as biosorbent material to remove Zn(II) ions from aqueous solutions. Biosorption - desorption studies revealed that the sphagnum peat as biosorbent could be regenerated using 0.1M HCl as eluting agent with more than 70% recovery in four successive biosorption - desorption cycles. The results showed that the sphagnum peat should be used as an alternative, effective and low - cost biosorbent for Zn(II) ions removal from polluted aqueous solution

Application of DVC-FISH method in tracking <i>Escherichia coli</i> in drinking water distribution networks

Sporadic detection of live (viable) <i>Escherichia coli</i> in drinking water and biofilm with molecular methods but not with standard plate counts has raised concerns about the reliability of this indicator in the surveillance of drinking water safety. The aim of this study was to determine spatial distribution of different viability forms of <i>E. coli</i> in a drinking water distribution system which complies with European Drinking Water Directive (98/83/EC). For two years coupons (two week old) and pre-concentrated (100 times with ultrafilters) water samples were collected after treatment plants and from four sites in the distribution network at several distances. The samples were analyzed for total, viable (able to divide as DVC-FISH positive) and cultivable <i>E. coli</i>. The results showed that low numbers of <i>E. coli</i> enters the distribution sytem from the treatment plants and tend to accumulate in the biofilm of water distribution system. Almost all of the samples contained metabolically active <i>E. coli</i> in the range of 1 to 50 cells per litre or cm² which represented approximately 53% of all <i>E. coli</i> detected. The amount of viable <i>E. coli</i> significantly increased into the network irrespective of the season. <br><br> The study has shown that DVC-FISH method in combination with water pre-concentration and biofilm sampling allows to better understand the behaviour of <i>E. coli</i> in water distribution networks, thus, it provides new evidences for water safety control

Separation of reducing sugars from lignocellulosic hydrolysate: Membrane experiments & system dynamic modelling

Separation of fermentable sugars after hydrolysis of lignocellulosic biomass plays a vital role in second-generation biofuel production. Byproducts and solid fractions generated during pretreatment and hydrolysis can have adverse effects on fermentation efficiency. Previous studies have shown that a maximum of 40% (w/w) of sugar yield can be obtained by sequential UF and NF permeate recovery. This study aimed to introduce a multi-step membrane filtration process to recover fermentable sugars while removing inhibitory bi-products. Fermentable sugar recovery was investigated using a recirculation flow between various stages of separation. The experimental results demonstrated that by introducing NF permeate recirculation to the UF unit a sequential UF/NF system can achieve 60% (w/w%) recovery of reducing sugars. Based on the experimental results, a ‘Simultaneous ultrafiltration and nanofiltration model’ was developed using system dynamics. The model was used to predict the final sugar concentration and sugar yield using sugar permeability in each membrane as the dynamic variability. The model predicts that high sugar permeability (or selective permeability) through the ultrafiltration mostly affects the efficiency of the system, which still is a challenge

Simultaneous nutrient and organic matter removal from wastewater by aerobic granular sludge process

Received: February 1st, 2023 ; Accepted: June 16th, 2023 ; Published: July 2nd, 2023 ; Correspondence: [email protected] granular sludge (AGS) technology offers several benefits, such as simultaneous removal of nutrients and organic matter from wastewater, stronger granule structure, excellent settleability, and high resistance to toxicity. However, the formation of granules can take a long time and needs to be dense and stable. In this study, the formation of aerobic granules in sequencing batch reactors (SBRs) using a granular activated carbon (GAC) and aluminium sulphate coagulant were evaluated for the simultaneous removal of nutrient (phosphorus (TP) and nitrogen (TN)) and organic matter (chemical oxygen demand (COD)) from wastewater. The reactors were continuously operated for 107 days and were fed with synthetic media and real domestic sewage. However, adaptation process with the synthetic wastewater led to relatively slow granulation process (sedimentation rate of sludge flocks was 3 m h-1 ). During the experiments, there was no visible formation of granules in SBRs based on the analysis of the sludge samples, only the formation of aggregate structures similar to flocks. However, the results showed that total phosphorus (TP) removal efficiency was over 90% in SBR operated with aluminium sulphate. However, COD and total nitrogen (TN) removals were higher in GAC SBR, 75% and 10%, respectively. Thus, even if granules are not developed yet, the system is working efficiently. The results of this study could be useful in the development of AGS technology for full-scale wastewater treatment plant

Comparison of phosphorus removal efficiency of conventional activated sludge system and sequencing batch reactors in a wastewater treatment plant

The aim of this study was to evaluate the effectiveness application of sequencing batch reactors (SBRs) for phosphorus removal compared to the conventional activated sludge (CAS) treatment system. The results showed that the removal efficiency of phosphorus reached about 99% at wastewater treatment plant with CAS system. At the same time, the maximum phosphorus removal efficiency can be achieved to 88% if the SBRs system operating parameters are optimized. Finally, this study demonstrated that even if granules are not fully developed, the SBR system is working with a good efficiency

Management of wastewater from landfill of inorganic fiberglass

ArticleSustainability is one of the key factors in smart environment management and include the reduction of environment footprint. The waste and wastewater management plans are aimed on actions to reduce the amount of waste and environmental pollution. This includes collection of waste, logistics, storage, processing or valorisation and also treatment. The aim of this research was to evaluate environmental pollution risk and to demonstrate one of the wastewater management schemes to reduce the pollution level. Evaluation of the better management scheme was performed in one of the landfills in Latvia, where fiberglass waste and other inorganic waste is stored. Onsite evaluation results demonstrated the need to develop a better wastewater management scheme of inorganic fiberglass landfill. After that, laboratory–scale experiments for conventional coagulation and biodegradation tests have been performed for efficient management

New device for air disinfection with a shielded UV radiation and ozone

Received: February 1st, 2021 ; Accepted: May 2nd, 2021 ; Published: May 7th, 2021 ; Correspondence: [email protected] air disinfection has become particularly relevant recently because of the Covid-19 pandemics. A shielded device for air and surface disinfection with UV radiation and ozone has been developed. It contains 28 low intensity (11 W) UV lamps (254 nm) in a specially designed three-dimensional grid to provide a large flow cross-sectional area and long path for the air particles to be irradiated. The device can be used in medical institutions, veterinary clinics, manufacturing plants, public premises, poultry, and livestock farms. It does not generate air-ions and ozone concentrations do not exceed the allowed 8-hour average values. The large number of UV lamps and powerful fans ensure air disinfection in large rooms in a relatively short time (400 m3 h -1 ). Simultaneously, the floor surface under the appliance is disinfected. Disinfection efficiency tests demonstrated 99.9999% reduction for Escherichia coli, Staphylococcus aureus and Pseudomonas phage Φ6 aerosols within a single transfer through the system (10 seconds of treatment). The housing of the device protects from direct UV radiation; therefore, people can be in the room during the operation of the device

Model water disinfection with electrolysis using TinO2n-1 containing ceramic electrodes

Water treatment with electrolysis was performed in a specially made electrolytic cell containing TinO2n-1 ceramic anode and Escherichia coli was used as a model organism for disinfection tests. The results showed that even relatively low energy input (0.5-2.5kWh*m-3, depending on water conductivity) in water samples with chloride ions concentration below 50mg*l-1, TinO2n-1 ceramic electrodes generated active chlorine in the range of 0.4-3.5mg Cl2*l-1, which is the level of chorine used for water disinfection. The results also confirmed that disinfection effect is a result of generation of oxidant species from chlorine rather than effect of electricity per se, or formation of radicals in water. At chloride ion concentration about 7mg*l-1 E. coli is not culturable, not able to divide and not respiring. Results showed that increase of the current above 0.02A at chloride ion concentration of 7mg*l-1 was sufficient to inactivate both culturable and viable but nonculturable (VBNC) E. coli. Notably, the ability of bacteria to divide (DVC positive) was lost more rapidly than their ability to respire. Kinetics of disinfection was studied in water sample which was treated with 0.02A at chloride ion concentration of 7mg*l-1. After about 15 minutes of exposure no culturable or able-to-divide E. coli were detected in the sample. Using the TinO2n-1 electrode in the electrolysis process with the presence of chloride ions, in concentration range which is common in raw waters, one can create a level of active chlorine that kills more than 99% of E. coli within 15 minutes. A practically applicable simple model for prediction of disinfection efficacy with electrolytic cell has been proposed