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

2013 ◽  
Vol 68 (12) ◽  
pp. 2698-2703 ◽  
Author(s):  
Matthew E. Verbyla ◽  
Stewart M. Oakley ◽  
Louis A. Lizima ◽  
Jie Zhang ◽  
Mercedes Iriarte ◽  
...  
Keyword(s):  
Retention Time ◽  
Hydraulic Retention Time ◽  
Taenia Solium ◽  
Treated Wastewater ◽  
Human Consumption ◽  
Dynamics Modeling ◽  
Hydraulic Residence Time ◽  
Stabilization Pond ◽  
Pond System ◽  
In Series

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.

Two-Phase Mesophilic Anaerobic Co-Digestion of Food Waste and Sewage Sludge: Effect of Hydraulic Retention Time

2014 ◽  
Vol 852 ◽  
pp. 789-796 ◽  
Author(s):  
Guo Hua Wang ◽  
Lei Wang ◽  
Xue Jun Tan ◽  
Yi Xian Wang ◽  
Feng Wang
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Food Waste ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Removal Rate ◽  
Two Phase ◽  
Acidogenic Reactor ◽  
In Series ◽  
The Impact

The impact of hydraulic retention time (HRT) on two-phase mesophilic (35°C) anaerobic co-digestion of food waste and sewage sludge was studied under mixing ratio of 1:1 on the TS basis. Laboratory-scale, two-phase anaerobic digestion systems were employed with each system consisting of an acidogenic reactor and a methanogenic reactor linked in series. For the acidogenic phase, an increase of volatile fatty acid (VFA) concentration was observed as HRT increased from 1d to 5d and the HRT of 5d was recommended for significantly higher VFA production and less propionate percentage, which could provide stable and favourable substrates for the methane reactor. Under acidogenic HRT of 5d, 20d was proved to be the optimum HRT for methanogenic phase with the methane content, methane production rate, methane yield and two-phase VS removal rate reached 71%, 0.7L/(L·d), 0.69L/gVSremoved and 64.7%, respectively. Results verified that the constraints of conventional anaerobic digestion for food waste or sewage sludge separately could be overcome by synergistic effect of co-digestion strategy and two-phase treatment.

Research on Performance Effected by HRT of PAC-MF Integrated Process

2010 ◽  
Vol 113-116 ◽  
pp. 1115-1118
Author(s):  
Cong Ma ◽  
Shui Li Yu ◽  
Li Wei ◽  
Lin Yan Zhang
Keyword(s):  
Retention Time ◽  
Hydraulic Retention Time ◽  
Membrane Separation ◽  
Removal Rate ◽  
Ammonia Nitrogen ◽  
High Dose ◽  
Hydraulic Residence Time ◽  
Water Treatment Process ◽  
Operation Conditions ◽  
Capital Construction

The hydraulic residence time (HRT) is a key parameter affecting the water treatment process, concerning water quality guarantee, short HRT will shrink capacity of structure, in order to reduce capital construction fee and operation cost. Filtration experiments using a bench-scale immersed membrane separation system combined with a high dose of PAC (powdered activated carbon) were conducted in order to investigate the effect for organic matters, pesticides and ammonia-nitrogen, and choose the optimal hydraulic retention time. The experiments were carried out under such operation conditions as a filtration rate of 0.5m/d, water temperature of 20°C. Synthetic water was used as the source water; the average influent concentrations of TOC (total organic carbon), and NH3-N (ammonia nitrogen) were 7.8mg/l, 6.8mg/l, respectively，201μg/L for THMFP and 201μg/L for Nitrobenzene. The results illustrated that, when HRT reduced from 3h to 1h, the removal rate of TOC, UV254 decreased a little, so did ammonia-nitrogen. But it had little effect on THMFP and nitrobenzene. When HRT was 1 hour, the average removal rate of TOC was 75%, 92% for ammonia-nitrogen, 97.5% for nitrobenzene and 75% for THMFP, which was all less than that of GB5749-2006 and that’s the optimal hydraulic retention time.

Removal of bacterial and viral faecal indicator organisms in a waste stabilization pond system in Choconta, Cundinamarca (Colombia)

2002 ◽  
Vol 45 (1) ◽  
pp. 61-66 ◽  
Author(s):  
C. Campos ◽  
A. Guerrero ◽  
M. Cárdenas
Keyword(s):  
Domestic Wastewater ◽  
Epidemiological Studies ◽  
Indicator Organisms ◽  
Bacterial Indicators ◽  
Stabilization Pond ◽  
Waste Stabilization Pond ◽  
Pond System ◽  
Waste Stabilization ◽  
In Series ◽  
Viral Indicators

A major objective for domestic wastewater treatment using waste stabilization pond systems is the removal of pathogenic microorganisms. Traditional evaluation parameters for faecal contamination are the total and faecal coliforms. However, epidemiological studies, environmental resistance and the behaviour in the treatment systems, show that viruses are an important disease agent and even more resistant to disinfection than bacteria. Therefore, it is important to introduce viruses as a faecal indicator and to compare them with the traditional bacterial indicators. A waste stabilization pond system was evaluated in the municipality of Chocontá, Cundinamarca (Colombia), for the removal of faecal indicators (such as Escherichia coli, Streptococcus faecalis, Clostridium perfringens) and viruses like F+, somatic and Bacteroides fragilis phages. The system includes two facultative ponds in series with a flow of 1555 m3/day. Samples were collected at the entrance of the system, in the two ponds and from the final effluent. Results show a decrease between 0.3 and 4.7 logarithmic units in the bacterial indicators and between 1 and 4.6 logarithmic units with viral indicators.

Ozonation of nursing home wastewater pretreated in a membrane bioreactor

2018 ◽  
Vol 78 (2) ◽  
pp. 266-278 ◽  
Author(s):  
Danièle Mousel ◽  
Johannes Pinnekamp
Keyword(s):  
Nursing Home ◽  
Organic Carbon ◽  
Retention Time ◽  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Hydraulic Retention Time ◽  
Plant Size ◽  
Treated Wastewater ◽  
Pharmaceutically Active Compounds ◽  
Recommended Dosage

Abstract Nursing home (NH) wastewater was pretreated in an ultrafiltration membrane bioreactor (MBR) and subsequently ozonated in a pilot plant in order to evaluate the elimination of pharmaceutically active compounds (PhACs). Dosing of the pre-treated wastewater with 5 mg ozone (O3) L−1 led to the elimination of >50% for nearly all investigated PhACs in the ozonation plant, whereas dosing 10 mg O3 L−1 increased elimination to >80%. A total hydraulic retention time of 12.8 min proved sufficient for PhAC elimination. Specific ozone consumption and influent dissolved organic carbon (DOC) (8.2–9.5 mg L−1) were in similar ranges for all three performed trials. Combining the MBR with subsequent ozonation at a dosage of 5 mg O3 L−1 achieved elimination of >90% and effluent concentrations below 250 ng L−1 for nearly all the investigated PhACs. Influent concentrations of the MBR were comparable to those found in municipal wastewater. Thus, the recommended dosage for PhAC elimination of 5 mg O3 L−1 (i.e. a specific consumption of 0.6 g O3*(g DOC)−1) is in the same range as for municipal wastewater. However, due to a smaller plant size, the specific costs for treating NH wastewater would significantly exceed those of treating municipal wastewater.

scholarly journals Effect of hydraulic retention time on hydrodynamic behavior of anaerobic-aerobic fixed bed reactor treating cattle slaughterhouse effluent

2017 ◽  
Vol 39 (4) ◽  
pp. 469 ◽  
Author(s):  
Daiane Cristina de Freitas ◽  
Fernando Hermes Passig ◽  
Cristiane Kreutz ◽  
Karina Querne de Carvalho ◽  
Eudes José Arantes ◽  
...  
Keyword(s):  
Flow Regime ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Fixed Bed ◽  
Theoretical Models ◽  
Fixed Bed Reactor ◽  
Bromophenol Blue ◽  
Eosin Y ◽  
Hydrodynamic Behavior ◽  
In Series

The study of the hydrodynamic behavior in reactors provides characteristics of the flow regime and its anomalies that can reduce biological processes efficiency due to the decrease of the useful volume and the hydraulic retention time required for the performance of microbial activity. In this study, the hydrodynamic behavior of an anaerobic-aerobic fixed bed reactor, operated with HRT (hydraulic retention time) of 24, 18 and 12 hours, was evaluated in the treatment of raw cattle slaughterhouse wastewater. Polyurethane foam and expanded clay were used as support media for biomass immobilization. Experimental data of pulse type stimulus-response assays were performed with eosin Y and bromophenol blue, and adjusted to the single-parameter theoretical models of dispersion and N-continuous stirred tank reactors in series (N-CSTR). N-CSTR model presented the best adjustment for the HRT and tracers evaluated. RDT (residence time distribution) curves obtained with N-CSTR model in the assays with bromophenol blue resulted in better adjustment compared to the eosin Y. The predominant flow regime in AAFBR (anaerobic aerobic fixed bed reactor) is the N-CSTR in series, as well as the existence of preferential paths and hydraulic short-circuiting. 

Modelling Nematode Egg Elimination in Wastewater Stabilization Ponds

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1659-1665 ◽  
Author(s):  
M. M. Saqqar ◽  
M. B. Pescod
Keyword(s):  
Retention Time ◽  
Effluent Quality ◽  
Stabilization Pond ◽  
Pond System ◽  
Intestinal Nematode ◽  
Stabilization Ponds ◽  
Nematode Eggs ◽  
Jet Velocity ◽  
Inflow Jet ◽  
Wastewater Stabilization Ponds

The paper analyses data on intestinal nematode egg numbers (NNE) taken over a 30-month period in a large wastewater stabilization pond system. The retention time of 8-10 days suggested by WHO as the treatment expected to achieve an effluent with less than 1 nematode egg per litre was not supported by the results. A model has been developed to describe the elimination of nematode eggs(NNE) in ponds. According to this model, 14 days theoretical retention time is required to achieve the above criterion in the Alsamra pond system. The importance of the inflow jet velocity in influencing effluent quality, in terms of NNE, has been demonstrated.

Removal of faecal coliforms in a wastewater stabilisation pond system in Mindelo, Cape Verde

1996 ◽  
Vol 34 (11) ◽  
pp. 149-157 ◽  
Author(s):  
M. Rångeby ◽  
P. Johansson ◽  
M. Pernrup
Keyword(s):  
Waste Water ◽  
Retention Time ◽  
Domestic Wastewater ◽  
Cape Verde ◽  
Faecal Coliform ◽  
Coliform Bacteria ◽  
Faecal Coliforms ◽  
Pond System ◽  
In Series ◽  
Influent Wastewater

In Mindelo, Cape Verde, domestic wastewater is treated in a waste water stabilisation pond system with the aim of reusing the water for agricultural purposes. The conductivity in influent wastewater is high and in order to minimise an increase in the conductivity the plant is operated with as low retention time as possible. An investigation was performed over two and a half months in 1995 with the aim of finding factors that affect the removal of faecal coliform bacteria. COD, conductivity, flow, pH and faecal coliforms were then followed through the system. The results show that the die-off rate, K, is high when the pH is high. The results also indicate that the retention time seems to be the most important factor, which means that the plant has to be operated with at least 3-4 maturation ponds in series and the inlets and outlets have to be constructed in a way that avoids short-circuiting. It was also found that not only the evapuation but also chemical and/or biological reactions affect the conductivity. This phenomenon will be investigated further.

The nitrogen removal potential of predenitrification systems in sensitive coastal areas

1995 ◽  
Vol 32 (7) ◽  
pp. 135-142
Author(s):  
E. Görgün ◽  
N. Artan ◽  
D. Orhon ◽  
R. Tasli
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Nitrogen Removal ◽  
Retention Time ◽  
Treatment Process ◽  
Hydraulic Retention Time ◽  
Domestic Sewage ◽  
Coastal Areas ◽  
Careful Evaluation ◽  
Denitrification Kinetics

Effective nitrogen removal is now required to protect water quality in sensitive coastal areas. This involves a much more difficult treatment process than for conventional domestic sewage as wastewater quantity and quality exhibits severe fluctuations in touristic zones. Activated sludge is currently the most widely used wastewater treatment and may be upgraded as a predenitrification system for nitrogen removal. Interpretation of nitrification and denitrification kinetics reveal a number of useful correlations between significant parameters such as sludge age, C/N ratio, hydraulic retention time, total influent COD. Nitrogen removal potential of predenitrification may be optimized by careful evaluation of wastewater character and the kinetic correlations.

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