Selected Wastewater Treatment Plants Research Articles

Using Quantitative Microbial Risk Assessment (QMRA) of SARS-CoV-2 to understand possible exposure to health risks in selected wastewater treatment plants located in the Eastern region of South Africa

In the past two years, Covid-19 has emerged as the most severe and pressing public health issue, causing a great deal of damage to societal and economic welfare, as well as causing illness and mortality. The operators in wastewater treatment plants (WWTPs), particularly those employed in rural communities, appear to often exhibit a lack of adherence to proper safety protocols by not utilizing sufficient protective equipment while handling unprocessed sewage samples throughout the different phases of wastewater treatment and disposal. This study aimed at examining the potential health risk of infection among WWTP operators, as a result of unintentional ingestion of wastewater during routine duties in facilities that receive influent containing Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) from various areas. This study examined the prevalence of SARS-CoV-2 in grab samples of untreated wastewater samples using the real-time quantitative polymerase chain reaction (RT-qPCR) technique and quantitative microbial risk assessment (QMRA) model was employed on three probable exposure of SARS-CoV-2 scenarios that are expressed as moderate, aggressive and extreme (2 mL, 10 mL, 20 mL) to evaluate the probability of infection to WWTP workers based on the 6 h that the workers spent in WWTPs performing their daily activities which exposed them to potential health risk of various pathogens. At the highest SARS-CoV-2 genome of 266.23 × 102 gc/mL, the findings indicated that there was no statistically significant difference in the probability of infections with respect to seasonal differences because the P(i) value was greater than 0.05 (p > 0.05). Overall, P(i) was highly significant across all volumetric scenarios in the study with p value that was p < 0.001. The probability of getting infected during the different seasons is assumed to be low since there was no statistically difference in P(i) with respect to season however it can be assumed that there is a high chance of getting infected regardless of volumetric intake. Our study suggests that the risk of accidental occupational exposure to SARS-CoV-2 in raw wastewater is negligible to workers whereby workers would perform their daily activities without wearing protective gear. Nevertheless, the importance and work of WWTPs by workers should not be overlooked. Regardless of the situation, it is widely recognized that residential wastewater poses a potential risk of infection due to the presence of several enteric pathogens, therefore, it is crucial to ensure that those who are occupationally exposed to untreated wastewater are well equipped with suitable personal protective equipment (PPE).

Effect of tourist activity on wastewater quality in selected wastewater treatment plants in the Balearic Islands (Spain)

Unregulated sewage discharge into the sea poses a considerable danger to marine ecosystems, with coastal regions being particularly vulnerable to this because of the impact of tourism. This issue is amplified during the summer season, as the Balearic Islands are a heavily frequented destination. This study aims to determine the water quality in five different wastewater treatment plants (WWTPs) representative on the islands. For this purpose, we analysed several parameters, including biochemical oxygen demand (BOD), chemical oxygen demand (COD), treated water flow, suspended solids (SS), nitrates (N) and phosphorus (P), at the inlet and outlet of the WWTPs for 5 years. We set particular thresholds for each parameter and documented any breach by comparing the findings with the existing regulations. The least favourable results indicate non-compliance regarding N and P levels throughout the entire study period, as well as a lack of reduction percentage. Furthermore, flow analysis reflects the significant influence of tourism on water quality, with notable increases in both population and treated water volume during the peak tourist season. Overall, the investigation offers a robust foundation for comprehending water quality in relation to coastal landscape in the Balearic Islands. It pinpoints significant worry spots and underscores tourism’s immediate impact on this ecological feature.

Assessment of microbial contamination of atmospheric air in a selected wastewater treatment plant

Assessment of microbial contamination of atmospheric air in a selected wastewater treatment plant

Meandering Flow Filter for Phosphorus Removal as a Component of Small Wastewater Treatment Plants—A Case Study

Chemical phosphorus removal in wastewater treatment plants can be carried out by precipitation with iron or aluminum salts or by filtering wastewater through a bed of active sorptive material. This work aimed to investigate whether using a meander flow filter filled with the sorption material Rockfos® would improve phosphorus removal efficiency in a selected wastewater treatment plant. Tests were performed under laboratory conditions using a model of a meander flow filter and a similar filter under field conditions at full technical scale. This filter was the final element of a hybrid constructed wetland located in the village of Białka in the municipality of Dębowa Kłoda in southeastern Poland. A laboratory model of a phosphorus removal filter with vertical incomplete baffles forcing a meandering water flow was constructed to determine the hydraulic conditions of the flow. After one year of operation, the filter with horizontal wastewater flow operating at its full technical scale (without meanders) was modified by inserting appropriate baffles that were analogous to those in the laboratory model. The analysis of the hydraulic conditions in the laboratory model showed that, under the assumed conditions, wastewater flows through the filter layer in a laminar motion, so such filters can be modeled using the Kozeny–Carman formula. It was shown that, after approximately a year of operation in a filter operating at full technical scale, before modification, dead spaces formed, thus causing the channel and primarily surface flow of wastewater. The phosphorus removal efficiency during this test period averaged 9.4%. After introducing baffles and forcing meander flow in the filter chamber, the efficiency increased to 40.6%. The results indicate that meander flow filters can improve phosphorus removal efficiency in small wastewater treatment plants.

Physicochemical properties of wastewater effluents from selected wastewater treatment plants

The majority of garbage that is dumped into the environment is the consequence of industrial activity, and this waste contains toxic and dangerous substances that have properties. Untreated industrial effluents have repeatedly affected the environment and human health. Additionally, the aim of this review is to determine if water treatment conforms to DWAF and USEPA criteria and to evaluate specific wastewater treatment facilities. Additionally, the effluent from companies was assessed after being collected utilizing composite sampling methods. The findings recognized pH, rivers, and industrial activities. This is a warning sign that the water is unsafe, demonstrating that industrial effluents are contributing to a reduction in river water quality. Receiving water near numerous food-processing facilities showed significant reductions after effluent discharge. As a result, when developing mitigation strategies, governments should consider this. Some of these strategies are enforcing the pollution laws that are already in place; setting up treatment facilities; turning industrial waste into biogas; educating the public; starting programs; and passing laws.

Grey Water Footprint of Contaminants of Emerging Concern from Wasterwater in Sava River Basin

Water pollution by contaminants of emerging concern (CECs) causes risks to both the environment and human health. We assessed water pollution by CECs in the Sava River basin in two monitoring campaigns carried out in May and July 2017. The grey water footprint (GWF) is a tool that converts the level of pollution by particular substances into the volume of water needed for dilution to a harmless level. Therefore, it can serve as an indicator for comparing various pollutants. The results show that substances that determine the GWF differ in individual locations. The highest value of the GWF was associated with 17β-estradiol, however, found only in one wastewater sample. The study showed that the value of the GWF in individual locations fluctuates and does not depend on the size of the wastewater treatment plant from which the wastewater is discharged. At selected wastewater treatment plants, a sustainability assessment was carried out using the Water Pollution Level indicator. The values in all cases were below the level of 1.0, indicating sustainable discharge; only in two cases did values reach the defined threshold to question the potential of non-sustainable discharge. The study contributes to earlier studies on the GWF and enlarges knowledge regarding the GWF of CECs.

Integration of sludge ozonation with anaerobic digestion: From batch testing to scenario analysis with energy, economic and environmental assessment

A methodological procedure, based on results from batch experiments, is proposed and applied to a selected wastewater treatment plant generating a poorly degradable sludge, to identify the best configuration and ozone dosage for full-scale application of sludge ozonation. Samples of pre-thickened and digested sludge were collected, tested at different ozone dosages and characterized to gather useful data for energy, economic and carbon footprint balances. The most viable scenario was found to be sludge pre-treatment at the lowest tested dosage (20 mg O3/g VS), yielding energy, cost and GHG emission net savings of 177 MWh/y, 57.8 k€/y and 6.38 Mg CO2-eq./y, respectively. Sensitivity analyses, conducted by varying the specific energy required for ozone generation and the unit costs for sludge disposal and resource supply, confirmed the stability of this scenario, whereas a field pilot-scale testing is advisable to verify modified process conditions for a safe and efficient application of sludge ozonation. The proposed methodology, including laboratory batch anaerobic digestion tests, scenario definition and energy/economic/environmental balances, could be preliminary applicable to all situations to broadly analyze all involved aspects and give a useful overview about the effective applicability of sludge ozonation.

Occurrence and Fate of Triclosan and Triclocarban in Selected Wastewater Systems across Durban Metropolis, KwaZulu-Natal, South Africa.

Triclosan (TCS) and triclocarban (TCC) are antimicrobial agents that have been used in personal care and consumer products in the past decades. In this study, influent, effluent, and sludge samples collected in selected wastewater treatment plants across the Durban metropolis were qualitatively and quantitatively investigated. It was revealed that the concentration of TCS ranged from 1.906 to 73.462 µg/L, from 1.732 to 6.980 µg/L, and from 0.138 to 2.455 µg/kg in influent, effluent, and sludge samples, respectively. The concentrations of TCC were found to be between 0.320 and 45.261 µg/L, <LOQ–1.103 µg/L, and from 0.107 to 8.827 µg/kg in the influent, effluent, and sludge samples, respectively. Higher concentrations of TCS as compared with TCC were observed in the aqueous samples. However, the concentrations of TCC in the sludge samples were significantly higher than the level of TCS. More water solubility of TCS could be responsible for the observed trend in the influent and effluent samples, while the trend observed in the sludge could be due to the more hydrophobicity character of TCC. The results of this study indicated that substantial amounts of TCS and TCC are been removed during the treatment process which could be a major reason for the decline in the levels recorded in the effluent samples, therefore, reducing the amount of the TCS and TCC that would eventually end up in the surface rivers. Qualitative analyses of the samples indicated the presence of caffeine, tert-butylhydroquinone, chloroxylenol, phenol, 4-(1,1,3,3-tetramethyl butyl), and dimethyl-bisphenol A. Further investigative ecological risk assessment studies are crucial due to the potential threat the contaminants may pose to aquatic lives and humans.

Risk Analysis of Heavy Metal Accumulation from Sewage Sludge of Selected Wastewater Treatment Plants in Poland

Sewage sludge (SS) from wastewater treatment plants (WWTPs) has important soil-forming and fertilizing properties. However, it may not always be used for this purpose. One of the main reasons why SS cannot be used for natural purposes is its heavy metal (HM) content. SS from the wastewater treatment plant in Poland was subjected to an analysis of the potential anthropogenic hazard of HMs, especially in terms of their mobility and accumulation in soil. Calculations were made for the concentrations of HMs in SS from the analyzed wastewater treatment plants and in arable soil from measurement points in places of its potential use. The geoaccumulation index (GAI), potential environmental risk index (PERI), risk assessment code (RAC) and environmental risk determinant (ERD) were calculated. Then the values of the indicators were compared with the mobility of HMs, which was the highest risk of soil contamination. It was shown that a high level of potential risk and geoaccumulation indicators did not necessarily disqualify the use of SS, provided that HMs were in immovable fractions.

Analysis of Heavy Metal Fraction Content in Sewage Sludge from Selected Wastewater Treatment Plants

Analysis of Heavy Metal Fraction Content in Sewage Sludge from Selected Wastewater Treatment Plants

Mass loading, distribution, and removal of antibiotics and antiretroviral drugs in selected wastewater treatment plants in Kenya

The discharge of active pharmaceutical ingredients (APIs) into the aquatic environment from wastewater effluents is a concern in many countries. Although many studies have been conducted to evaluate the APIs removal efficiencies and emissions to the environment in wastewater treatment plants (WWTPs), most of these studies considered the aqueous and sludge phases, disregarding the suspended particulate matter (SPM) phase. To try to understand the role of the SPM, the occurrence of five most common antibiotics and three antiretroviral drugs (ARVDs) commonly used in Kenya were investigated in this study. APIs partitioning and mass loading in influents and effluents of three different WWTPs: trickling filters, stabilization ponds, and decentralized fecal sludge system, were evaluated. API concentration levels ranging from ˂LOQ (limit of quantification) to 92 μgL−1 and ˂LOQ to 82.2 mgkg−1 were observed in aqueous samples and solid samples respectively, with SPM accounting for most of the higher concentrations. The use of the aqueous phase alone for determination of removal efficiencies showed underestimations of API removal as compared to when solid phases are also considered. Negative removal efficiencies were observed, depending on the compound and the type of WWTP. The negative removals were associated with deconjugation of metabolites, aggregated accumulation of APIs in the WWTPs, as well as unaccounted hydraulic retention time during sampling. Compound characteristics, environmental factors, and WWTPs operation influenced WWTPs removal efficiencies. Wastewater stabilization ponds had the poorest removals efficiencies with an average of −322%. High total mass loads into the WWTPs influent and effluent of 22,729 and 22,385 mg day−1 1000 PE−1 were observed respectively. The results aims at aiding scientists and engineers in planning and designing of WWTPs. Findings also aim at aiding policy-making on pharmaceutical drug use and recommend proper wastewater management practices to manage the high mass loading observed in the WWTPs.

Energy saving in wastewater treatment plants: A methodology based on common key performance indicators for the evaluation of plant energy performance, classification and benchmarking

Wastewater treatment plants are a major energy user in the urban water cycle with an energy demand estimated in several countries in about the 1% of the overall national energy use. Nevertheless, the sector offers wide opportunities for energy saving and recovery to be fostered in order to reduce economic and environmental impacts. Nowadays, a consolidated procedure to assess energy performances in the wastewater sector is still not available. This work proposes a methodology for the evaluation, benchmarking and labelling of energy performances of wastewater treatment plants, based on easy-to-define data related to energy use and operative parameters. Statistical techniques are applied to validate input data and the step-by-step derived outcomes. Common key performance indicators were calculated and linearly aggregated in a global index able to convey the wastewater treatment plant energy performance. Such index allowed to carry out comparisons among energy consumptions supported by a dedicated built-up database collecting sectorial data, considered as a reference. A case study based on 10 selected wastewater treatment plants is proposed. The methodology led to derive a clear and affordable overview of the analysed plant energy performances. Moreover, the benchmarking analysis allowed to get, on the basis of the differences between the calculated global index values, a rough estimation of the potential energy gains achievable if suitable measures for ameliorating the plant energy efficiency performance are adopted. For three of the selected plants, the margins for energy savings resulted higher than 60%. The methodology suggests to focus on such cases by carrying out specific on-site inspection to detect energy use inefficiencies and define suitable actions addressed to save energy and enhance the system sustainability. In this view, the proposed procedure could also be applied with the aim of prioritizing actions to pursue energy savings among a large set of wastewater treatment plants.

Physicochemical properties of wastewater effluent from two selected wastewater treatment plants (Cape Town) for water quality improvement

Effluent from wastewater treatment plants (WWTPs) is one of the main sources of pollution that seriously affect the physicochemical parameters in water bodies. This occurs particularly when partially treated or untreated effluent is released to various aquatic ecosystems. This constitutes a potential danger to the general environment. To safeguard the lives of human, aquatic and other living organisms, regular monitoring of wastewater effluent to ascertain their compliance with both national and international regulatory limits for water quality improvement is very crucial. This research work was carried out using standard methods to evaluate ten physicochemical parameters from the effluent of two WWTPs in Cape Town, South Africa. Our findings were: temperatures (16.90–25.33 °C), pH (5.85–7.85), EC (923.00–1294.17 µS/cm), TDS (590.72–828.27 mg/L), DO (1.30–5.50 mg/L), SO42− (3.23–163.18 mg/L), COD (23.70–898.58 mg/L), BOD (9.17–252.44 mg/L), Cl− (48.17–378.48 mg/L) and PO43− (0.10–11.32 mg/L). Temperature, pH and SO42− levels in the two WWTPs were within the recommended limit for wastewater discharge by the Department of Water Affairs and Forestry (DWAF), South Africa and the United State Environmental Protection Agency (USEPA). However, other parameters did not comply fully with both DWAF and USEPA standards. The result showed that effluents from these WWTPs are possible sources of pollution to the receiving water bodies and calls for enhancement of the WWTPs operations to ensure safe effluent discharge.

Detection of Pharmaceutical Residues in Surface Waters of the Eastern Cape Province.

Pharmaceuticals are emerging contaminants in the aquatic environments. Their presence poses toxicological effects in humans and animals even at trace concentrations. This study investigated the presence of antibiotics, anti-epilepsy and anti-inflammatory drugs in river water of selected rivers in the Eastern Cape Province in South Africa. Enzyme-linked immunosorbent assay was used for screening of sulfamethoxazole and fluoroquinolones antibiotics. The samples were collected in upper-stream, middle-stream and lower-stream regions of the rivers and effluent of selected wastewater treatment plants. Pre-concentration of the samples was conducted using lyophilisation and extraction was conducted using solid phase extraction (SPE) on Waters Oasis hydrophilic-lipophilic-balanced cartridge. The percentage recovery after sample clean-up on SPE was 103% ± 6.9%. This was followed by ultra-performance liquid chromatography electrospray ionization tandem mass spectrometry. The detected analytes were sulfamethoxazole, erythromycin, clarithromycin and carbamazepine. Carbamazepine and erythromycin were detected in high concentrations ranging from 81.8 to 36,576.2 ng/L and 11.2 to 11,800 ng/L respectively, while clarithromycin and sulfamethoxazole were detected at moderate concentrations ranging from 4.8 to 3280.4 ng/L and 6.6 to 6968 ng/L, respectively. High concentrations of pharmaceuticals were detected on the lower-stream sites as compared to upper-stream sites.

Quantity not quality: promoting sustainable wastewater practices in Jordan

AbstractJordan, the second most water-scarce country in the world, is gradually increasing its reliance on treated wastewater for its water supply; more than 90% of treated wastewater is used either in agricultural or industrial activities in Jordan. However, in Jordan, all treated wastewater plants are constructed upstream of dams, the latter being used to store treated wastewater. Most dams in the country were originally constructed to collect freshwater through rainfalls. Mixing this source of freshwater with treated wastewater decreases the dams' water quality. This study examines the effects of mixing freshwater with treated wastewater in dams by comparing water samples from the outflows of selected wastewater treatment plants and different dams with historical hydrochemical data of dam water before the diversion of treated wastewater. This study finds that the quality of dam water, in which freshwater has been mixed with treated wastewater, notably decreases. Hence, this study formulates policy recommendations on how to ensure a sustainable water supply that ensures the quality necessary to different water uses, making the suggestion of a separate storage system in dams.

Phytotoxicity of sewage sludge from selected wastewater treatment plants - new opportunities in sewage sludge treatment

Purpose The research was focused on evaluating phytotoxicity of sewage sludge from two selected wastewater treatment plants in Czech Republic. Methods Laboratory experiments were carried out with samples of sewage sludge, which were focused on the evaluation of their phytotoxicity by using the PhytotoxkitTM testing set. Specifically, the inhibitory/stimulating effect was established on the growth of roots from the seeds of white mustard (Sinapis alba L.). The chosen proportions of sewage sludge were 10%, 30% and 50%. The test was conducted in three repetitions. Additionally, the research also included a comparison of the effect of compost addition to the sewage sludge and its potentially increased stimulating effect on the growth of roots from the seeds of white mustard (Sinapis alba L.). Ratios of compost were 5%, 15%, 25% and 50%. The test was conducted in three repetitions. Results Stimulating effect on the growth of white mustard (Sinapis alba L.) was demonstrated only in samples with the sludge proportion of 10%. The results also show that the addition of compost reduced phytotoxicity of sewage sludge in all three tested ratios (5%, 15%, 25% and 50%). Conclusion It was found out that the addition of compost resulted in the decreased phytotoxicity of all tested sewage sludge samples, and hence in their suppressed inhibitory effect.

Energy Balance of WWTP Using LCA Analysis

In connection with the optimization of operation at the selected Wastewater Treatment Plant (WWTP), it is important to perform an energy audit with an assessment of the use of electricity and the subsequent economic optimization of the equipment of the WWTP. We can perform the energy balance through Life Cycle Assessment (LCA) analysis in relation to EN ISO 140 40 [1].The aim of this study case is the analysis of the energy balance of WWTP. The appraisal was performed on three different interpretation variants of specific electricity consumption. The conclusion is a comparison of variants of quantification of specific electricity consumption.

Evaluation of the efficiency of selected wastewater treatment processes in removing selected perfluoroalkyl substances (PFASs)

In this study, the efficiencies of selected wastewater treatment plants (WWTPs) to remove selected perfluoroalkyl substances (PFASs) during wastewater treatment processes were evaluated. For this purpose, influent samples from Daspoort, Zeekoegat and Phola WWTPs, were initially screened for the presence of sixteen different PFASs of which only seven were detected. These include: perfluorobutanoic acid (PFBA), perfluoro-n-pentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), perfluorohexane sulfonate (L-PFHxS), and perfluorooctane sulfonate (L-PFOS).To determine the concentrations of these PFASs, wastewater samples were subjected to solid-phase extraction followed by liquid chromatography-tandem mass spectrometry. The results showed that L-PFOS was the dominant compound with the highest concentration of 508 ± 258 ng/L at Daspoort WWTP. Overall, the three WWTPs could not achieve the complete influent-to-effluent removal of the PFASs and the best removals were observed at Zeekoegat WWTP.The removal efficiency of the different unit processes varied from one plant to another and also from each type of PFASs. At Daspoort, the removal efficiency of the primary settling tanks was poor and the highest removal reached 39% for PFHxA. The activated sludge (AS) of this WWTP achieved the highest removal of 84% for the L-PFOS. At Zeekoegat, the AS achieved the highest removal of 94% for the L-PFOS. The anaerobic pond at Phola achieved a higher removal of 80% for the L-PFOS. However, no removal was observed downstream of the biological filter for the same compound. Poor removal efficiency was reported downstream of the wetland at Phola except for the PFOA (16%).

Effluent Quality Assessment of Selected Wastewater Treatment Plant in Jordan for Irrigation Purposes: Water Quality Index Approach

Effluent Quality Assessment of Selected Wastewater Treatment Plant in Jordan for Irrigation Purposes: Water Quality Index Approach

Concentration and reduction of antibiotic residues in selected wastewater treatment plants and receiving waterbodies in Durban, South Africa

In the province of KwaZulu-Natal, South Africa the incidence of resistant tuberculosis, upper respiratory tract diseases as well as diarrhoeal and parasitic infections is high. Treatment of these diseases with antibiotics is partly reflected by the excretion of the respective antibiotics and their subsequent occurrence in wastewater. Their quantitative reduction in wastewater treatment reflects their potential environmental as well as human impact, the latter due to the use of the recipient water for domestic purposes and for irrigation. Information of the occurrence and reduction of different classes of antibiotics in wastewater treatment is sparse, especially the particle bound fraction of these. Due to this, analyses of aqueous and particle bound antibiotics in untreated wastewater of four selected wastewater treatment plants (WWTPs) and their receiving water bodies was carried out in Durban, South Africa. The treatment step especially considered was the biological one, represented by activated sludge and trickling filters. The treatment further included secondary clarifiers and final chlorine disinfection. Composite samples were collected during the period February 2017 to May 2017 and analysed with online solid phase extraction – high performance liquid chromatography mass spectrometry (SPE-HPLC-MS). For the 13 assessed antibiotics, the limit of detection (LOD) and the limit of quantification (LOQ) ranged from 0.07 to 0.33 ng L−1 and 0.23 to 1.09 ng L−1 respectively, while the total percentage recovery was in the range of 51 to 111%. The percentage of individual antibiotics bound to the particulate fraction normally lost by sample (influent) filtration, if not analysed in parallel, was in the range of 2.6%–97.3% (n = 32). In this fraction (sludge from centrifuge sample), the concentration of bound antibiotics of all the target antibiotics were detected in the influent of all WWTP in concentration ranges between 1.3 ng L−1 (Azithromycin; AZI) to 81,748 ng L−1 (Ciprofloxacin; CIP). The antibiotics with the highest median concentrations in receiving water bodies of the respective WWTP were; Sulfamethoxazole; SUL (239 ng L−1) WWTP “K”, Ciprofloxacin; CIP (708 ng L−1) WWTP “S” and Albendazole; ALB (325 ng L−1 and 683 ng L−1) WWTP “P” and “I” respectively.The overall percentage removal efficiency for the four WWTPs ranged from 21% to 100%. The biological treatment steps, activated sludge and trickling filters, were effective in removing antibiotics especially with the trickling filter and the impact of the sedimentation stage after activated sludge treatment.