Post-treatment of anaerobic effluents in constructed wetland systems

2001 ◽  
Vol 44 (4) ◽  
pp. 213-219 ◽  
Author(s):  
J. T. de Sousa ◽  
A. C. van Haandel ◽  
A. A.V. Guimarães
Keyword(s):  
Suspended Solids ◽  
Control Unit ◽  
Coarse Sand ◽  
Post Treatment ◽  
Uasb Reactor ◽  
Municipal Sewage ◽  
Nitrogen And Phosphorus ◽  
Treatment Unit ◽  
Hydraulic Load ◽  
Pre Treatment

This papers describes the behaviour of wetlands as a post-treatment unit for anaerobically treated sewage for the removal of organic matter, suspended solids, nutrients (nitrogen and phosphorus) and faecal coliforms. Raw sewage was treated in a UASB reactor with a retention time of 5 h and the effluent was used in four units of wetlands with coarse sand as the medium and operated with different hydraulic loads. Three of the units had emerging macrophytes (Juncus sp), whereas the fourth one was operated as a control unit without plants. During the 12 months of operation, the organic material removal efficiency (measured as COD) was in the range of 79 to 85%, whereas suspended solids removal varied from 48 to 71%. Faecal coliform removal was very high (99,99%); phosphorus was also efficiently removed (average efficiency of 90% for the lowest hydraulic load), but nitrogen removal was only partial (45 to 70% for ammonia and 47 to 70% for TKN). The experimental results clearly show the technical feasibility of using wetlands for treatment of municipal sewage after a pre-treatment in the UASB reactor.

Performance of constructed wetland systems treating anerobic effluents

2003 ◽  
Vol 48 (6) ◽  
pp. 295-299 ◽  
Author(s):  
J.T. de Sousa ◽  
A. van Haandel ◽  
E.P.C. Lima ◽  
A.V.A. Guimaraes
Keyword(s):  
Removal Efficiency ◽  
Suspended Solids ◽  
Carbonaceous Material ◽  
Uasb Reactor ◽  
First Year ◽  
Faecal Coliforms ◽  
Nitrogen And Phosphorus ◽  
Operational Conditions ◽  
Operation Period ◽  
Hydraulic Load

The purpose of this present paper is to verify the performance of three wetland systems operated with effluents from a UASB reactor, with respect nutrient removal (nitrogen and phosphorus), pathogenic organisms and remaining carbonaceous material, monitored over a three-year period. The experiment was carried out and monitored at PROSAB (Programa de Saneamento Básico) in Campina Grande, Para'ba. The removal efficiency of the carbonaceous material expressed in DQO ranged from 70 to 86%, but concerning the total suspended solids, the efficiency ranged from 50 to 71%. The removal efficiency in terms of nitrogen and phosphorus of both vegetated systems was about 65.5 to 86%, respectively, during the first year of operation. Under the operational conditions of the experiment, the removal of phosphorus in a wetland system containing washed sand as the substratum decreased, as its operation period increased. The vegetated wetland has been the most efficient in removing faecal coliforms (roughly 4 log units) as compared to the non-vegetated one (about 3 log units), when both were operated with the same hydraulic load (2.3 cm. per day). Thus, the effluent produced over the three-year period ranged from 800 to 1,800 UFC/100 mL in the analyzed samples.

Combination of a UASB reactor and a curtain type DHS (downflow hanging sponge) reactor as a cost-effective sewage treatment system for developing countries

2000 ◽  
Vol 42 (3-4) ◽  
pp. 83-88 ◽  
Author(s):  
I. Machdar ◽  
Y. Sekiguchi ◽  
H. Sumino ◽  
A. Ohashi ◽  
H. Harada
Keyword(s):  
Sewage Treatment ◽  
Cost Effective ◽  
Ammonia Nitrogen ◽  
Treatment System ◽  
Uasb Reactor ◽  
Municipal Sewage ◽  
Combined System ◽  
Treatment Unit ◽  
Pre Treatment ◽  
Sewage Treatment System

The second generation of our originally proposed sewage treatment system, which consists of a UASB reactor as an anaerobic pre-treatment unit and curtain-type DHS (downflow hanging sponge) reactor as an aerobic post-treatment unit, was installed at a municipal sewage treatment site. A 550-day continuous experiment demonstrated that the whole combined system successfully achieved 94–97% of unfiltered-BOD removal, 81–84% of unfiltered-COD removal, and 63–79% of SS removal, at an overall HRT of 8 h (6 h for UASB and 2 h for DHS units). The combined system performed an excellent organic removal as well as a fairly efficient nitrification, i.e. 52–61% of ammonia-nitrogen removal. Our proposed combined system possesses prominent advantages: requiring neither external aeration input nor excess sludge withdrawal.

scholarly journals The Contribution of Cognitive Impulsivity to Criminal Risk

2021 ◽  
Author(s):  
◽  
Rebecca K. Bell
Keyword(s):  
Impulse Control ◽  
Post Treatment ◽  
Trait Anger ◽  
Special Treatment ◽  
Treatment Programme ◽  
Treatment Change ◽  
Anger Control ◽  
Treatment Unit ◽  
Cognitive Behavioural ◽  
Pre Treatment

<p>Impulsivity increases risk for general, violent and sexual offending. Accordingly, helping offenders to become better regulators of their impulses is one goal of offender rehabilitation. In a correctional setting, the assessment of impulsivity focuses on personality and behaviour, but not cognition; cognitive impulse control impairments are inferred from personality styles and behavioural patterns suggestive of acting before thinking. However, empirical findings challenge the validity of inferring cognition from personality and behavioural measures. Additionally, without assessing cognition, practitioners are limited in their ability to isolate which cognitive processes are most impaired and therefore worthy of intervention for individual offenders.  To establish the contribution of cognitive impulse control to criminal risk, a theoretically derived, empirically supported neurocognitive assessment framework was adopted. The framework is based on the notion that impulsive behaviour arises from three, potentially dissociable skill domains that support impulse control: decisionmaking, perceptual and motor impulse control. A cohort of 77 men attending intensive cognitive-behavioural rehabilitation was recruited from four of New Zealand’s prison-based Special Treatment Unit Rehabilitation Programmes (STURPs). A neurocognitive battery of five tasks collectively representing each cognitive impulse control domain was administered before and after the 8-month treatment programme.  Study One explored pre-treatment clinically impaired performance within and across each cognitive impulse control domain. Compared to normative data, performance was typically in the average to below average range, but it was not clinically impaired overall. When performance was clinically impaired, it was most pronounced on tasks requiring cognitive flexibility.  Study Two explored treatment change in cognitive impulse control. The study also compared pre-treatment cognitive impulse control between offenders who went on to complete the treatment programme and those who were prematurely removed for responsivity or conduct-related issues. No pre-treatment cognitive impulse control differences were found between treatment completers and non-completers. Treatment completers displayed small pre-post treatment improvements in some areas of cognitive impulse control, but not others.  Study Three explored cross-sectional and predictive relationships between cognitive impulse control, dynamic criminal risk, trait anger and anger control. Although there was little association between these variables before treatment, some cognitive impulse control outcomes predicted post-treatment dynamic criminal risk, trait anger and anger control. Thus, the evidence suggested that certain aspects of cognitive impulse control might function as facilitators of treatment change.  Together, the findings highlighted the importance of evaluating cognitive impulse control as part of the risk assessment, and clinical formulation process. The findings also suggested that interventions designed to develop cognitive impulse control abilities either before, or as a complement to traditional cognitive-behavioural interventions, have the potential to maximise treatment response.</p>

Performance and behaviour of planted and unplanted units of a horizontal subsurface flow constructed wetland system treating municipal effluent from a UASB reactor

2013 ◽  
Vol 68 (7) ◽  
pp. 1495-1502 ◽  
Author(s):  
Jocilene Ferreira da Costa ◽  
André Cordeiro de Paoli ◽  
Martin Seidl ◽  
Marcos von Sperling
Keyword(s):  
Suspended Solids ◽  
Subsurface Flow ◽  
Oxygen Demand ◽  
Post Treatment ◽  
Filter Medium ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Horizontal Subsurface Flow

A system composed of two horizontal subsurface flow constructed wetlands operating in parallel was evaluated for the post-treatment of UASB (upflow anaerobic sludge blanket) reactor effluent, for a population equivalent of 50 inhabitants per unit. One unit was planted with cattail (Typha latifolia) and the other was unplanted. The study was undertaken over a period of 4 years, comprising monitoring of influent and effluent constituents together with a full characterization of the behaviour of the units (tracer studies, mathematical modelling of chemical oxygen demand (COD) decay, characterization of solids in the filter medium). The mean value of the surface hydraulic load was 0.11 m3m−2d−1, and the theoretical hydraulic retention time was 1.1 d in each unit. Using tracer tests with 82Br, dispersion number (d) values of 0.084 and 0.079 for the planted and unplanted units were obtained, indicating low to moderate dispersion. The final effluent had excellent quality in terms of organic matter and suspended solids, but the system showed low capacity for nitrogen removal. Four-year mean effluent concentration values from the planted and unplanted units were, respectively: biochemical oxygen demand (BOD5): 25 and 23 mg L−1; COD: 50 and 55 mg L−1; total suspended solids (TSS): 9 and 9 mg L−1; N-ammonia: 27 and 28 mg L−1. The COD decay coefficient K for the traditional plug-flow model was 0.81 and 0.84 d−1 for the planted and unplanted units. Around 80% of the total solids present in the filter medium were inorganic, and most of them were present in the interstices rather than attached to the support medium. As an overall conclusion, horizontal subsurface flow wetlands can be a very suitable post-treatment method for municipal effluents from anaerobic reactors.

A novel and cost-effective sewage treatment system consisting of UASB pre-treatment and aerobic post-treatment units for developing countries

1997 ◽  
Vol 36 (12) ◽  
pp. 189-197 ◽  
Author(s):  
Izarul Machdar ◽  
Hideki Harada ◽  
Akiyoshi Ohashi ◽  
Yuji Sekiguchi ◽  
Hiroyuki Okui ◽  
...  
Keyword(s):  
Developing Countries ◽  
Low Cost ◽  
Sewage Treatment ◽  
Cost Effective ◽  
Post Treatment ◽  
Cod Removal ◽  
Treatment System ◽  
Treatment Unit ◽  
Pre Treatment ◽  
Sewage Treatment System

A novel sewage treatment system was proposed, which consists of a UASB anaerobic pre-treatment unit and the following DHS (downflow hanging sponge-cubes) aerobic post-treatment unit, as a low-cost and easy-maintenance process for developing countries. Over six months experiment by feeding sewage our proposed system achieved 94% of total-COD removal, 81% of soluble-COD removal, and nearly perfect SS removal and total-BOD removal at the overall HRT of 8.3 hr (7 hr in UASB and 1.3 hr in DHS unit). Moreover, the DHS reactor was capable of performing high (73–78%) nitrification. Our whole system requires neither external aeration input nor withdrawal of excess sludge.

scholarly journals Performance of an Integrated Membrane Process with Electrochemical Pre-Treatment on Poultry Slaughterhouse Wastewater Purification

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 256
Author(s):  
Kulyash Meiramkulova ◽  
Davud Devrishov ◽  
Mikhail Zhumagulov ◽  
Sholpan Arystanova ◽  
Zhaskhaiyr Karagoishin ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Removal Efficiency ◽  
Physicochemical Parameters ◽  
Membrane Filtration ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Total Suspended Solids ◽  
Treatment System ◽  
Treatment Unit ◽  
Pre Treatment

Industrial activities produce a variety of pollutants that may not be easily treated using centralized wastewater treatment systems based on a single treatment unit. The variability of the pollutants brings the importance of industrial-specific integrated wastewater treatment plants such as integrated membrane filtration systems. However, the performance of a membrane filtration process can be highly affected by the presence of high amounts of suspended particles in the raw wastewater. Therefore, proper selection of a pre-treatment unit prior to a membrane filtration wastewater treatment system is a key aspect of its performance. This study investigated the performance of an integrated membrane filtration treatment system connected to an electrochemical process (pre-treatment) on the purification of a poultry slaughterhouse wastewater toward achieving a high-quality effluent. The industrial-scale treatment plant installed at the Izhevsk Production Corporative (PC) poultry farm in Kazakhstan is composed of an electrochemical, ultrafiltration (UF), and reverse osmosis (RO) as the main treatment units. From the analysis results, the electrochemical pre-treatment unit was observed to be highly effective for the removal of some physicochemical parameters such as turbidity, color, total suspended solids, total iron, aluminum, chemical oxygen demand, and biochemical oxygen demand; with removal efficiency ranging from 71 to 85%. The low removal efficiency of the pre-treatment system was also observed from free and total chlorine, nitrites, nitrates, phosphates, and ammonium nitrogen; with removal efficiency ranging from 4 to 45%. While in general, the overall treatment train was observed to be highly efficient for some physicochemical parameters such as turbidity, color, total suspended solids, as well as chemical and biochemical oxygen demand; maintaining almost 100% removal efficiency throughout the study period. Also, the high removal efficiency of the electrochemical pre-treatment processes led to a relatively low rate of cake formation on the membrane filters.

Experiences of nitrogen and phosphorus removal in deep-bed filters at henriksdal sewage works in Stockholm

1998 ◽  
Vol 37 (9) ◽  
pp. 193-200
Author(s):  
L. Jonsson
Keyword(s):  
Phosphorus Removal ◽  
Pilot Plant ◽  
Suspended Solids ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Exponential Relationship ◽  
Iron Salts ◽  
Hydraulic Load ◽  
Filter Bed ◽  
H 20

Deep-bed down-flow two-media filters were used in pilot plant studies with filtration of secondary settled wastewater. FeSO4 or FeCl5 was applied as a precipitation agent, and NaAc·3H2O was chosen as a carbon source when denitrification was desired. The concentration of PO4-P in the filtrate from the pilot plant study never exceeded 0.05 mg PO4-P/l when iron salts were dosed. The curves showing the concentration of P-tot and PO4-P in the filtrate as a function of the quotient between the dosage of iron and the concentration of PO4-P in the influent to the filter followed approximately an exponential relationship. The total nitrogen reduction over the filter bed increased from an average of 2.3 mg (NO3+NO2)-N/l at the beginning of each experiment to an average of 4.3 mg (NO3+NO2)-N/l towards the end of the test. When only secondary settled wastewater, suspended solids, primary settled wastewater, iron salts, or sodium acetate was added, at a hydraulic load of 10 m/h, the time before clogging became 100 h, 10–15 h, 20–40 h, respectively. Almost the entire pressure drop was located on the surface of the filter bed and 0.25 metre down in the expanded clay layer.

Monitoring of rain events with a submersible UV/VIS spectrophotometer

2008 ◽  
Vol 57 (10) ◽  
pp. 1587-1593 ◽  
Author(s):  
Aurélien Maribas ◽  
Nadège Laurent ◽  
Philippe Battaglia ◽  
Maria do Carmo Lourenço da Silva ◽  
Marie- Noeëlle Pons ◽  
...  
Keyword(s):  
Large Scale ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Treatment Unit ◽  
Reject Water ◽  
Rapid Changes ◽  
Treatment Train ◽  
Pre Treatment ◽  
Rain Events

A submersible UV/VIS spectrophotometer has been implemented on the pre-treatment unit of a large-scale wastewater treatment plant (350,000 person-equivalent) to monitor the rapid changes in total Suspended Solids and total Chemical Oxygen Demand occurring during rain events as well as injections of reject water from the sludge treatment train or wasted activated sludge. Calibration has been proven to be difficult for fast composition-varying streams but the device is able to monitor qualitatively sudden quality changes, in spite of the noise affecting the signal.

Characterisation of medical-waste sterilisation-plant wastewater and a preliminary study of coagulation–flocculation treatment options

2010 ◽  
Vol 62 (2) ◽  
pp. 266-272 ◽  
Author(s):  
O. Özkan ◽  
H. Mıhçıokur ◽  
Ş. T. Azgın ◽  
Ö. Özdemir
Keyword(s):  
Ferric Chloride ◽  
Ph Value ◽  
Treatment Options ◽  
Oxygen Demand ◽  
Medical Waste ◽  
Municipal Sewage ◽  
Nitrogen And Phosphorus ◽  
Aluminium Sulfate ◽  
Coagulant Dosage ◽  
Pre Treatment

Wastewater from a medical-waste sterilisation plant (MWSP) contains unique pollutants and requires on-site treatment to prevent contamination of the municipal sewage system and receiving water bodies. Therefore, to meet the prescribed discharge standards and comply with the legal regulations, pre-treatment must be applied to MWSP wastewater. In this study, the capabilities of coagulation–flocculation processes were investigated for MWSP wastewater treatment. Processes using ferric chloride, ferrous sulfate and aluminium sulfate as coagulants were characterised. During the coagulation experiments, seven different coagulant dosages and four different pH values were evaluated to determine the optimum coagulant dosage and pH value. The highest removal efficiency of chemical oxygen demand (COD) was obtained using 300 mg/L of ferric chloride at pH 10. A COD removal of about 60% as well as considerable reductions in the amounts of suspended solids, nitrogen and phosphorus were realised.

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