Removal Of Helminth Eggs Research Articles

Avaliação da eficácia da solução hidroalcoólica de própolis com glicina na redução conjunta de microrganismos e ovos de helmintos em vegetais de folhas verdes

Abstract The main goal of this study was to evaluate the effectiveness of a propolis hydroalcoholic solution with glycine on the reduction of microorganisms and helminth eggs removal in lettuce leaves. Three experimental groups were evaluated in triplicate or replicates: microbiological (ME), parasitological (PE), and microbiological and parasitological (MPE). Before the experiments, the initial concentration of the native microbiota was assessed by counting mesophilic aerobes, molds and yeasts, using conventional microbiological techniques. Lettuce leaves were washed in tap water and subjected to different immersion treatments: propolis hydroalcoholic solution (PHS), propolis hydroalcoholic solution at pH 5.5 (PHS2), and propolis hydroalcoholic solution with glycine (PHS-glycine). In ME, propolis hydroalcoholic solution combined or not with glycine, was evaluated on the reduction of native microbiota. Residual microbiological contamination was assessed. In the PE, the effect of PHS2 and PHS-glycine was evaluated on the removal of a known number of Ascaris suum eggs on leaves artificially contaminated. In MPE, PHS-glycine was evaluated on the reduction of native microbiota and removal of eggs. A reduction of more than 2 log CFU/g was observed in ME. In PE, PHS-glycine removed 37.22% of eggs. In MPE, the PHS-glycine reduced 3.3 CFU/g of mesophilic aerobes, 5.0 log CFU/g of fungi, and 35.53% of eggs from vegetables. The results highlighted the solution’s efficiency in reducing or eliminating different contaminants in vegetables and reinforced the need for the development of hygiene methods that do not harm human health and are reproducible at the household level.

Fecal sludge treatment in a pilot-scale vertical-flow constructed wetland for the removal of helminth eggs

Abstract Eliminating parasites in fecal sludge (FS) remains one of the major concerns in developing countries. To address this issue, experiments were conducted in triplicate vertical-flow constructed wetland (VFCW) units corresponding to free flow, 7 days and 14 days of retention time (RT). The effect of plant density on the system's performance was monitored in each planted bed unit and compared to the non-planted unit (standard). Following a bi-monthly application rate of FS at a nominal load of 200 kg TS m−2 year−1, the performance of the system in terms of helminth egg removal was calculated for each hydraulic RT tested. Untreated FS applied on the bed units contained high parasitic egg loads with a median number of 62.51 helminth eggs/g. The removal efficiencies of helminth eggs ranged from 82 to 100% in the leachates and were affected by the hydraulic RTs and the presence of plants (p < 0.05). On the other hand, accumulated biosolids on the bed units still contained high concentrations of pathogens exceeding the WHO standards and should not be applied directly in agriculture.

Improvement of Log Reduction Values Design Equations for Helminth Egg Management in Recycled Water

Understanding and managing the risk posed by helminth eggs (HE) is a key concern for wastewater engineers and public health regulators. The treatment processes that produce recycled water from sewage at wastewater treatment plants (WWTPs) rely on achieving a defined log10 reduction value (LRV) in HE concentration during the production of recycled water from sewage to achieve the guideline concentration of ≤1.0 HE/L. The total concentration of HE in sewage reaches thousands of HE/L in developing countries and therefore, an LRV of 4.0 is generally accepted to achieve a safe concentration in recycled water, as this will meet the guideline value. However, in many developed countries with good sanitation and public health standards, the HE concentration in sewage is generally <10 HE/L. Therefore, validation of the sewage treatment process relied on to achieve an LRV of 4.0 can be difficult. Because of these limitations, design equations to predict LRVs from hydraulic retention times (HRT), which are geographically non-specific, are commonly relied on to ensure the production of safe quality recycled water with respect to HE. However, these design equations could be further refined by defining the design and management of the treatment process in greater detail and thus be used more effectively for determining the LRV required. This paper discusses the limitations and possible improvements that could be applied to LRV design equations for predicting HE removal at WWTPs and identifies the data requirements to support these improvements. Several options for LRV design equations are proposed that could be validated experimentally or via the ongoing operation of WWTPs. These improvements have the potential to assist the rationalization of the HE removal requirements for specific treatment options, exposure scenarios and use of recycled water in agriculture.

Degradation and accumulation rates of fresh human excreta during vermicomposting by Eisenia fetida and Eudrilus eugeniae

This study was carried out to assess the degradation and accumulation rates of fresh human excreta and how addition of anal cleansing materials affect performance during vermicomposting by Eisenia fetida and Eudrilus eugeniae. Vermicomposting setups consisting of two transparent containers (length 0.27 m, breadth 0.17 m and depth 0.12 m) stacked on top of each other were installed and operated under laboratory conditions. Earthworms, Eisenia fetida and Eudrilus eugeniae, were obtained from Green Cycle Technologies Limited in Accra, Ghana and the species verified and cultured before use. Fresh human excreta for feeding the experimental setups was collected from an Enviro-loo public toilet and 13 g applied to the setups daily. Similar setups were fed with 0.3 g of anal cleansing material in addition to the fresh excreta. A setup without any earthworms (NW) was set up as a control. Physicochemical characteristics of vermicompost accumulating in the setups were determined weekly for 28 days using standard laboratory procedures while the sludge accumulated in the various setups were weighed and recorded daily. One-way analysis of variance (ANOVA) and Post-hoc LSD tests were conducted to determine whether the differences in results between the two earthworm species and among setups with and without anal cleansing materials were statistically significant (p ≤ 0.05). The study showed 12.3% and 26.2% reduction in volatile solids in EE (Eudrilus eugeniae and excreta only) and EF (Eisenia fetida and excreta only) while ash content increased indicating good degradation. The percentage mass reductions recorded at the end of the fourth week were 67.5%, 58.8% and 40.5% in systems EE, EF and NW respectively, while reductions of 73.7% and 68.5% were realized in EEA (Eudrilus eugeniae with excreta and toilet paper) and EFA (Eisenia fetida with excreta and toilet paper) respectively. There was greater amount of sludge accumulated in systems without earthworms, 0.00020 m3 (59.5%) in NW, than in systems with earthworms where 0.00011 m3 (32.5%) and 0.00014 m3 (41.2%) were recorded for EE and EF respectively. The rate of accumulation in vermibeds EE and EF was relatively higher than in vermibeds with excreta and toilet paper (EEA and EFA). EEA and EFA recorded accumulation rates of 0.00009 m3 (26.3%) and 0.00011 m3 (31.5%) respectively. Complete removal of helminth eggs was not achieved in any of the treatment systems.

Effectiveness of helminth egg reduction by solar drying and liming of sewage sludge.

The present study is aimed at assessing the effectiveness of solar drying process in terms of helminth egg reduction in sewage sludge (SS) generated from an activated sludge wastewater treatment plant (WWTP) in Marrakesh city (Morocco). It is also engaged to highlight a synergic effect of liming (1% CaO) and solar drying on helminth egg reduction. The solar drying process was conducted for 45days, in summer under a semi-arid climate in a pilot scale polycarbonate-based tunnel (2m3). Before undergoing solar drying process, data showed an important load of helminth eggs including Ascaris sp., Schistosoma spp., Capillaria spp., Trichuris spp., Ankylostome spp., Toxocara spp., and Taenia spp. in limed sludge (LS) and non-limed sludge (NLS) (15.2 and 17.9 eggs/g, respectively). Ascaris eggs were the most abundant (11.2 and 13.5 eggs/g in LS and NLS, respectively). By the end of the solar drying process, a considerable removal of the total helminth eggs was recorded in LS and NLS (92.8% and 91.6%, respectively). A complete removal of Schistosoma spp., Capillaria spp., Trichuris spp., Toxocara spp. and Taenia spp. was noted in LS and NLS. In the case of Ankylostome spp., data showed a total removal in LS and 81% in NLS; however, the final load is in agreement with the standards (0.4 egg/g). As for Ascaris spp., neither liming nor solar drying process allowed a complete removal (91% and 90% in NLS and LS, respectively) and the final load (1.1 egg/g) does not fulfill the WHO requirements for an agricultural use. Principal component analysis (PCA) demonstrated a negative correlation between dry matter (DM) content (hence temperature) and helminth egg concentration. No significant synergic effect of liming and solar drying process was showed by statistical analysis. This is substantiating that temperature is the key parameter involved in helminth egg removal while undergoing solar drying of SS.

Innovative Multistage Constructed Wetland for Municipal Wastewater Treatment and Reuse for Agriculture in Senegal

This paper reports on the performance of using a multistage constructed wetland (CW) to treat municipal raw wastewater and an analysis of its suitability for agricultural irrigation. The pilot plant consists of two stages of vertical flow CWs plus one stage of a horizontal CW built in 2018 with different local materials at the Gaston Berger University Campus, Saint Louis (Senegal). Each CW stage is composed of several filters with different type of media (silex, granite, or river gravel), filtering media depths, and macrophytes (Phragmites and Typha). The physicochemical and microbiological indicators were monitored over six months at each bed inlet and outlet to evaluate the efficiency and achievements of the Senegalese, European, and WHO regulations/recommendations for disposal or reuse in irrigation. This study demonstrates the viability of this new multistage CW design to treat raw municipal wastewater and produce an effluent of good quality suitable for reuse in agriculture. The removal of organic matter, suspended solids, and nutrients was very high (>95% for SS, BOD5 and N-NH4+, >90% for COD and P-PO43−), as was the reduction of microbiological indicators (fecal coliform reduction >5 log units and helminth egg removal of 100%). First, trends related to the influence of design (the type of gravel, filter depth, and type of macrophyte), operational modes, and the CW treatment efficiency were determined. The use of non-crushed gravel and Typha spp. seemed to provide better removal rates. On the contrary, no differences were found between the use of silex or granite gravel. For the studied Senegalese conditions under dry and hot climates, the preliminary results indicate that no resting periods are necessary for vertical flow CWs (VFCWs), thus resulting in a reduction in construction and operation costs. The main outcome of our study is evidence that multistage CWs can provide robust, cost-effective treatments, as well as allow for safe water reuse, which is imperative in areas with severe water scarcity and endemic microbiological waterborne diseases.

Blackwater processing via vermifiltration: Worm-based toilet (wormlet) in the arid context of Burkina Faso

In Burkina Faso, faecal sludge is mostly discharged into the environment untreated, with associated public health risks. Thus, sanitation technology that efficiently treats Blackwater (BW) in-situ is urgently required. This paper reports the design and testing of a proposed worm-based toilet (wormlet). The presence of E.eugeniae (EE) is found to reduce the total accumulated BW by a maximum of 61.74%. Over five to ten weeks, 1 kg of BW (dry portion) can be processed to 0.49–0.61 kg of vermicast by the EE. The wormlet effluent is of superior quality, as the log 10 removal efficiency of the bedding and filter matrix reached 7.45 and 5.85 for E. coli and faecal coliform, respectively. Helminth egg removal was found to be 97% within the 75-cm depth. Average organics and nutrient removal efficiencies are 99–100% for total solids and total suspended solids; 99% and 98% for the biochemical and chemical oxygen demand, respectively. Removal efficiencies between 97 and 99% were found for NH4+, NO3−, NO2−, and PO43−. A 100% turbidity removal was found in the systems containing charcoal. Thus, the wormlet appears to be superior for in-situ BW treatment, generating sub-products that can be reused or safely discarded.

Potential of Adding Constructed Wetland/Fishpond to Waste Stabilization Ponds to Improve Helminths Removal in Morogoro Municipality, Tanzania

A study was conducted to establish the potential of constructed wetlands in Morogoro Urban District, Tanzania, to remove helminths from wastewater. The standard wastewater treatment regime was failing to effect reliable removal of helminth eggs and larvae from six wastewater stabilization ponds. An alternative wastewater treatment regime for the ponds, coupled with a constructed wetland and a fishpond, was devised. Water, soil, and vegetable samples were tested for the presence of helminth larvae and eggs in a time series design over one growing season. From March to August 2014, experimental plots of carrots and Swiss chard were irrigated with wastewater that had been treated by the alternative wastewater treatment regime. It was found that the alternative wastewater treatment regime coupled with the constructed wetland and fishpond appeared to remove helminths completely. No helminths were found in the wastewater after it passed through the alternative system, and none were found in the market-ready carrots and chard. Numbers of helminth larvae and eggs showed evidence of seasonality, which is potentially useful knowledge for farmers in order to avoid helminth infection: almost all larvae were found at the end of the hot dry season. Monsoon rains followed and washed the helminth larvae and eggs away and none were found at the end of the season. Keywords : wastewater stabilization ponds, constructed wetlands, helminth removal, hookworm, sewage treatment

Evaluation of Occurrence, Concentration, and Removal of Pathogenic Parasites and Fecal Coliforms in Three Waste Stabilization Pond Systems in Tanzania.

In Tanzania, waste stabilization ponds (WSPs) are employed to treat wastewater, and effluents are used for urban agricultural activities. The use of untreated or partially treated wastewater poses risks of disease transmission, including parasitic and bacterial infections, to exposed communities. Little is known about the occurrence, concentration, and removal of parasites and fecal coliform (FC) bacteria in WSPs in Tanzania. This study evaluates the occurrence and concentration of parasites and FCs in wastewater, the efficiency of WSPs in removing parasites and FCs, and the validity of using FCs as an indicator of parasites. This was a cross-sectional study conducted between February and August 2018. Wastewater samples were collected from three WSPs located in the Morogoro, Mwanza, and Iringa regions. APHA methods were used to test physicochemical parameters. The modified Bailenger method and Ziehl–Neelsen stain were used to analyse parasites. Membrane filtration method was used to analyse FCs. Data were analysed using IBM SPSS version 20. Helminth egg removal ranged from 80.8% to 100%. Protozoan (oo)cyst removal ranged from 98.8% to 99.9%. The Mwanza WSP showed the highest FC reduction (3.8 log units (100 mL)−1). Both the parasites and FCs detected in the effluents of assessed WSPs were of higher concentrations than World Health Organization and Tanzania Bureau of Standards limits, except for helminths in the Morogoro WSP and FCs in the Mwanza WSP. FCs were significantly correlated with protozoa (p < 0.01) and predicted protozoa occurrence well (p=0.011). There were correlations between physicochemical parameters, parasites, and FC bacteria in the WSP systems. Inadequate performance of these systems may be due to lack of regular maintenance and/or systems operating beyond their capacity. FC indicators were observed to be a good alternative for protozoa monitoring, but not for helminths. Therefore, during wastewater quality monitoring, helminths should be surveyed independently.

Helminth eggs inactivation efficiency by sludge co-composting under arid climates

ABSTRACT Primary sludge (PS) from the wastewater treatment plants is constituted of organic matter and other nutrients that could be reused as soil fertilizers. However, primary sludge amendment is hampered due to the presence of pathogens that could be responsible for several infections in various ways depending on the prevalence of the human sources. This study investigates helminth eggs (HE) removal and inactivation efficiency by co-composting. So, PS was mixed with date palm waste as a bulking material at a 1:1 volume ratio. The C/N ratio decreased from 25:1 to 12:1 and temperatures above 50ºC were observed since 33 days. The initial concentration of HE eggs in the PS is 135.9 per 10 g DR. Microscopic examination of the PS, according to the Bailenger method, showed the presence of nematodes and Cestodes represented by: Ascaris lombricoïde, Ancylostomes duodenale, Trichuris trichiura, Capilaria spp, Hymenolepis nana, Taenia saginata, and Ascaris lombricoïde. After 60 days of co-composting, the charge of parasites was reduced to 18 eggs per 10 g per DR. The viability of ascaris eggs was examined using a light microscope and the percentage of the embryonated eggs was determined. No viable eggs were observed in the final compost. The result corroborates the WHO guidelines for the application of the composted sewage sludge safely for agriculture purposes.

Removal of helminth eggs by centralized and decentralized wastewater treatment plants in South Africa and Lesotho: health implications for direct and indirect exposure to the effluents

Wastewater may contain contaminants harmful to human health; hence, there is the need for treatment before discharge. Centralized wastewater treatment systems are the favored treatment options globally, but these are not necessarily superior in reduction of pathogens as compared to decentralized wastewater treatment systems (collectively called DEWATS). This study was therefore undertaken to assess the soil-transmitted helminth (STH) and Taenia sp. egg reduction efficiency of selected anaerobic baffled reactors and planted gravel filters compared to centralized wastewater treatment plants in South Africa and Lesotho. The risk of ascariasis with exposure to effluents from the centralized wastewater treatment plants was also assessed using the quantitative microbial risk assessment (QMRA) approach. Eggs of Ascaris spp., hookworm, Trichuris spp., Taenia spp., and Toxocara spp. were commonly detected in the untreated wastewater. The DEWATS plants removed between 95 and 100% of the STH and Taenia sp. eggs, with centralized plants removing between 67 and 100%. Helminth egg concentrations in the final effluents from the centralized wastewater treatment plants were consistently higher than those in the WHO recommended guideline (≤ 1 helminth egg/L) for agricultural use resulting in higher risk of ascariasis. Therefore, in conclusion, DEWATS plants may be more efficient in reducing the concentration of helminth eggs in wastewater, resulting in lower risks of STH infections upon exposure.

Effect of dewatering and composting on helminth eggs removal from lagooning sludge under semi-arid climate.

In this work, we assessed the drying and composting effectiveness of helminth eggs removal from sewage sludge of a lagoon wastewater treatment plant located in Chichaoua city. The composting was run after mixing sludge with green waste in different proportions: M1 (½ sludge + ½ green waste), M2 ([Formula: see text] sludge + [Formula: see text] green waste), and M3 ([Formula: see text] sludge + [Formula: see text] green waste) for 105days. The analysis of the dewatered sewage sludge showed a load of 8-24 helminth eggs/g of fresh matter identified as Ascaris spp. eggs (5-19 eggs/g) followed by Toxocara spp. (0.2 to 2.4 eggs/g); Hookworm spp. and Capillaria spp. (0.4-1 egg/g); Trichuris spp., Taenia spp., and Shistosoma spp. (< 1 egg/g) in the untreated sludge. After 105days of treatment by composting, we noted a total reduction of helminth eggs in the order of 97.5, 97.83, and 98.37% for mixtures M1, M2, and M3, respectively. The Ascaris spp. eggs were reduced by 98% for M1 and M3 treatments and by 97% for M2 Treatment. Toxocara spp., Hookworm spp., Trichuris spp., Capillaria spp., and Shistosoma spp. eggs were totally eliminated (100% decrease) and the Taenia spp. was absent from the first stage of composting. These results confirm the effectiveness of both dehydrating and composting processes on the removal of helminth eggs.

EFFECT OF CO-COMPOSTING ON HELMINTH EGGS REMOVAL

This study concerns the effectiveness of helminth eggs elimination during co-composting of activated sludge from a wastewater treatment plant mixed with ligno-cellulosic waste in a ratio of either 1/3-2/3 or 1/2-1/2 for 180 days. The Analysis of the initial sludge showed a load of 4-27 nematode eggs /g fresh matter identified as Ascaris sp., Capillaria sp. and Trichuris sp. During the co-composting stabilization phase, the reduction of the number of eggs varied between 50 and 90%. At the end of the process, reduction reached 100% for all the helminth ova. These results confirm the effectiveness of co-composting on their removal. Thereby, the final compost complied with the WHO guidelines for the safe reuse of fecal sludge.

Efficiency of two sewage treatment systems (activated sludge and natural lagoons) for helminth egg removal in Morocco.

Morocco is a country known for its vulnerability of water resources because of its arid and semi-arid climate. Thus, recycled wastewater has been suggested for agricultural activities, but contamination of these wastewaters is a major concern. The current study aims to determine the occurrence of helminth eggs in urban wastewater and to evaluate the removal of these pathogens by two sewage treatment systems: activated sludge and natural lagoons. The samples of wastewater and sludge were collected from two wastewater treatment plants (WWTP) located in Marrakech and Chichaoua, Morocco. Parasitological identification, according to the Bailenger technique, showed the presence of Nematodes and Cestodes, which are pathogenic to humans and animals and are responsible for helminthiasis. The wastewater and sewage sludge samples from Marrakech carried Ascaris lumbricoïdes, Ancylostoma duodenale, Trichuris trichiura, Capillaria spp., Taenia spp. and Hymenolepis spp., while the samples from Chichaoua carried Ascaris lumbricoïdes, Ancylostoma duodenale, Trichuris trichiura and Capillaria spp. The overall removal efficiency of eggs in the treatment plants ranged from 100% in the WWTP of Marrakech using activate sludge to 94.97% in the WWTP of Chichaoua using natural lagoons. These results were discussed according to health risk and the cost-effectiveness of both wastewater treatment techniques.

Pathogens and fecal indicators in waste stabilization pond systems with direct reuse for irrigation: Fate and transport in water, soil and crops

Wastewater use for irrigation is expanding globally, and information about the fate and transport of pathogens in wastewater systems is needed to complete microbial risk assessments and develop policies to protect public health. The lack of maintenance for wastewater treatment facilities in low-income areas and developing countries results in sludge accumulation and compromised performance over time, creating uncertainty about the contamination of soil and crops. The fate and transport of pathogens and fecal indicators was evaluated in waste stabilization ponds with direct reuse for irrigation, using two systems in Bolivia as case studies. Results were compared with models from the literature that have been recommended for design. The removal of Escherichia coli in both systems was adequately predicted by a previously-published dispersed flow model, despite more than 10years of sludge accumulation. However, a design equation for helminth egg removal overestimated the observed removal, suggesting that this equation may not be appropriate for systems with accumulated sludge. To assess the contamination of soil and crops, ratios were calculated of the pathogen and fecal indicator concentrations in soil or on crops to their respective concentrations in irrigation water (termed soil-water and crop-water ratios). Ratios were similar within each group of microorganisms but differed between microorganism groups, and were generally below 0.1mLg−1 for coliphage, between 1 and 100mLg−1 for Giardia and Cryptosporidium, and between 100 and 1000mLg−1 for helminth eggs. This information can be used for microbial risk assessments to develop safe water reuse policies in support of the United Nations' 2030 Sustainable Development Agenda.

Yaya-Beas, R.-E., et al. Helminth Egg Removal Capacity of UASB Reactors under Subtropical Conditions. Water 2015, 7, 2402–2421

The authors wish to make the following corrections to their paper [1]: [...]

Helminth Egg Removal Capacity of UASB Reactors under Subtropical Conditions

This research was conducted to study the anaerobic sludge filtration capacity regarding helminth egg removal in upflow anaerobic sludge blanket (UASB) reactors. Two 25 L lab-scale UASB reactors were operated at an ambient temperature which varied between 17.1 and 28.6 °C. Ascaris suum egg was selected as the model egg considering its similarity in terms of size and morphology to Ascaris lumbricoides, a human pathogen. Ascaris suum eggs were obtained from female parasites of infected pigs. The anaerobic sludge filtration capacity was performed applying upflow velocities between 0.09 and 0.68 m·h−1. Three sludge bed heights in the range of 0.30–0.40 m, 0.50–0.60 m and 0.60–0.70 m were applied. These sludge bed heights corresponded to 19%–25%, 31%–38% and 38%–44% of the total reactor height, respectively. Under the mentioned conditions, the average helminth egg removal efficiency was reciprocally correlated to the imposed upflow velocity. The studied lab-scale reactors reported an average helminth egg removal between 34%–100%, 30%–91% and 34%–56%, when the sludge bed in the UASB reactor was 19%–25%, 31%–38% and 38%–44% of the total reactor height, respectively. The decreased filtration capacity at increasing sludge bed heights might be likely related to biogas production and channeling formation. The average helminth egg removal efficiency in the control experiments performed without any sludge bed, by plain sedimentation, varied between 44% and 66%.

Overall performance evaluation of shallow maturation ponds in series treating UASB reactor effluent: Ten years of intensive monitoring of a system in Brazil

Maturation (polishing) ponds operating after UASB (upflow anaerobic sludge blanket) reactors are considered a highly suitable system for treating domestic sewage for small to medium communities in warm-climate developing countries. Important attributes are operational simplicity, good organic matter and nitrogen removal, excellent pathogen removal and lower land requirements compared to traditional pond systems. However, most papers in the literature focus on single studies investigating one particular aspect of this system. The objective of the current paper is to present a broad evaluation of one particular system (UASB reactor, three shallow ponds and a coarse rock filter in series) in Brazil treating sewage from 250 inhabitants over a period of 10 years. The study covers in an integrated manner the removal and behaviour of several variables, such as organic matter (BOD and COD), solids, nitrogen fractions, phosphorus, coliforms, pathogenic bacteria, helminth eggs, sulphides, surfactants and organic micropollutants (diethylphthalate, bis(2ethylhexyl)phthalate and bisphenol A). Even with short hydraulic retention times in each pond (2 to 6 days), the results endorse the good capacity for organic matter and ammonia removal and excellent removal of coliforms, helminth eggs and sulphides. Removal of phosphorus, surfactants and selected micropollutants was limited.

Removal of total coliforms, thermotolerant coliforms, and helminth eggs in Swine production wastewater treated in anaerobic and aerobic reactors.

The present work evaluated the performance of two treatment systems in reducing indicators of biological contamination in swine production wastewater. System I consisted of two upflow anaerobic sludge blanket (UASB) reactors, with 510 and 209 L in volume, being serially arranged. System II consisted of a UASB reactor, anaerobic filter, trickling filter, and decanter, being also organized in series, with volumes of 300, 190, 250, and 150 L, respectively. Hydraulic retention times (HRT) applied in the first UASB reactors were 40, 30, 20, and 11 h in systems I and II. The average removal efficiencies of total and thermotolerant coliforms in system I were 92.92% to 99.50% and 94.29% to 99.56%, respectively, and increased in system II to 99.45% to 99.91% and 99.52% to 99.93%, respectively. Average removal rates of helminth eggs in system I were 96.44% to 99.11%, reaching 100% as in system II. In reactor sludge, the counts of total and thermotolerant coliforms ranged between 105 and 109 MPN (100 mL)−1, while helminth eggs ranged from 0.86 to 9.27 eggs g−1 TS.

Taenia eggs in a stabilization pond system with poor hydraulics: concern for human cysticercosis?

The objective of this study is to compare the removal of Taenia eggs to the removal of Ascaris eggs in a wastewater stabilization pond system consisting of three ponds in series, where the hydraulic residence time distribution has been characterized via a tracer study supported by computational fluid dynamics modeling. Despite a theoretical hydraulic retention time of 30 days, the peak dye concentration was measured in the effluent of the first pond after only 26 hours. The smaller-sized Taenia eggs were detected in higher concentrations than Ascaris eggs in the raw wastewater. Ascaris eggs were not detected in the pond system effluent, but 45 Taenia eggs/L were detected in the system effluent. If some of these eggs were of the species Taenia solium, and if the treated wastewater were used for the irrigation of crops for human consumption, farmers and consumers could potentially be at risk for neurocysticercosis. Thus, limits for Taenia eggs in irrigation water should be established, and precautions should be taken in regions where pig taeniasis is endemic. The results of this study indicate that the theoretical hydraulic retention time (volume/flow) of a pond is not always a good surrogate for helminth egg removal.