Use of a mass balance model for developing guidelines for treatment plant recycle streams

2001 ◽  
Vol 1 (4) ◽  
pp. 169-176
Author(s):  
K.H. Carlson ◽  
W.H. Bellamy
Keyword(s):  
Treatment Effectiveness ◽  
Treatment Plant ◽  
Significant Risk ◽  
Balance Model ◽  
Sludge Dewatering ◽  
Adequate Treatment ◽  
Materials Balance ◽  
Treatment Conditions ◽  
The Impact ◽  
Plant Treatment

Recycling treatment, plant waste streams has become an important issue and the EPA is currently developing a rule for controlling and potentially limiting these streams. The impact to the overall treatment process and the relative risk of various recycle streams can be evaluated with a materials balance model of a treatment plant. A steady-state materials balance model was developed and applied to the recycle of backwash waste water, clarifier sludge supernatant and sludge dewatering supernatant. Recycling backwash water reduced the plant treatment effectiveness from 3.0 log to 2.95 log removal when the recycle stream was treated (0.5 log removal) and 2.84 log removal when not treated. Recycling clarifier sludge supernatant resulted in a reduction of performance from 3.0 log to 2.78 log removal with adequate treatment (0.5 log removal) and 1.95 log removal with inadequate treatment (10% removal). The model was used to identify vulnerable treatment conditions. Conventional treatment with a poorly operated or upset clarifier was identified as a significant risk with the overall treatment effectiveness decreasing from 3.0 to 2.3 log removal.

scholarly journals Analysis of risk factors for developing complications while treating pulpitis

2014 ◽  
Vol 95 (2) ◽  
pp. 231-235
Author(s):  
T V Aksenova ◽  
A N Bondarenko
Keyword(s):  
Risk Factors ◽  
Treatment Effectiveness ◽  
Significant Risk ◽  
Low Frequency ◽  
Study Groups ◽  
Rehabilitation Program ◽  
Recovery Potential ◽  
Periodontal Infection ◽  
Complications Rate ◽  
The Impact

Aim. To study the influence of different risk factors on complications rate while treating pulpitis. Methods. Retrospective analysis of 130 patients with pulpitis outpatient’s cards, who were treated by vital and devitalized pulp extirpation without additional rehabilitation (63 patients) and with addition of individually selected rehabilitation program (67 patients), was carried out. The presence and rate of risk factors for complications in both study groups were analyzed, the level of their impact in complications formation was assessed. The data were processed by analysis of variance. Results. The most significant risk factors for developing complications while treating pulpitis were low local dental and general recovery potential, multiple foci of dental and periodontal infection, mastication muscles malfunction, malocclusion, mental disorders. 60% of patients had the combination of 3 and more risk factors, which in half of all cases were associated with developing complications, if endodontic treatment of pulpitis was not associated with individually selected rehabilitation. Rehabilitation included physiotherapy (if indicated), e.g. low-frequency alternating magnetic field, intra-channel iodine electrophoresis, individually selected homeopathic drugs, Bach flower essences and kinesiotherapy in addition to full mouth debridement. Conclusion. The impact of a range of risk factors, which can be revealed in conditions of common outpatient dental practice, on pulpitis treatment effectiveness was revealed. The addition of individually selected rehabilitation program, targeted on revealed risk factors elimination, to traditional pulpitis treatment decreases the complications rate.

scholarly journals Prevalence of carotid artery disease in patients with metabolic syndrome

2020 ◽  
Vol 12 ◽  
Author(s):  
Tatjana Deleva-Stoshevska
Keyword(s):  
Metabolic Syndrome ◽  
Risk Factor ◽  
Carotid Artery ◽  
Carotid Artery Disease ◽  
Significant Risk ◽  
Adequate Treatment ◽  
Effective Prevention ◽  
Linear Probe ◽  
Artery Disease ◽  
The Impact

There is a growing body of scientific evidence on the impact of metabolic syndrome (MetS) on the progression of atherosclerosis, imposing the need for research of the association of MetS with carotid artery disease (CAD) as a significant risk factor for cerebrovascular insult (CVI) and transient ischemic attack (TIA). The aim of the study was to determine the prevalence of CAD as a risk factor for CVI and TIA in subjects with MetS. Material and methods: A cross-sectional study was performed including a total of 118 subjects, 65 men, 53 women, with MetS according to NCEP ATP III criteria that were analyzed clinically, biochemically and ultrasonographically in the City General Hospital "8th September" - Skopje in the period from January 2017 to January 2018. Waist circumference, blood pressure, glycemia, triglycerides, and HDL cholesterol were determined according to standard routine protocols. The evaluation of the extracranial carotid trunk was done with a Color Doppler Duplex sonography with a linear probe of 7.5MHz. CAD assessment was performed using Ultrasound Consensus Criteria for Carotid Stenosis. An objective neurological assessment of the existence of CVI and TIA was performed by a standard protocol for neurological examination and brain CT results from medical history were reviewed. Results: The prevalence of CAD in this study was 77 subjects (65.25%), of which 35 subjects (29.66%) had symptomatic CAD, 17 subjects (48.57%) had CVI, 18 subjects (51.43%) had TIA. Regarding the degree of carotid artery stenosis (CAS) in the total number of subjects with MetS and CAD, no subjects with normal findings were registered, 16 subjects had stenosis <50% , 29 subjects had stenosis 50-69% , 23 subjects had stenosis 70-99% , while 9 subjects had occlusion. Conclusion: The results obtained in this study have shown that asymptomatic CAD is dominant in patients with MetS, which further imposed the need for timely extracranial ultrasonographic evaluation of the carotid trunk. This would achieve both effective prevention and adequate treatment of CVI and TIA, thereby reducing morbidity and mortality from cerebrovascular events which has a great health and socioeconomic significance.

scholarly journals Impact on the Quality of Life When Living Close to a Municipal Wastewater Treatment Plant

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
A. Vantarakis ◽  
S. Paparrodopoulos ◽  
P. Kokkinos ◽  
G. Vantarakis ◽  
K. Fragou ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Significant Risk ◽  
Municipal Wastewater Treatment ◽  
Municipal Wastewater Treatment Plant ◽  
The Impact

The objective of the study was to investigate the impact on the quality of life of people living close to a municipal wastewater treatment plant. A case control study, including 235 inhabitants living within a 500 m radius by a municipal wastewater treatment plant (cases) and 97 inhabitants living in a different area (controls), was conducted. A standardized questionnaire was self-completed by the participants which examined the general health perception and the overall life satisfaction. Also, the concentration of airborne pathogenic microorganisms in aerosol samples collected around the wastewater treatment plant was investigated. Significant risk for symptoms such as headache, unusual tiredness, and concentration difficulties was recorded and an increased possibility for respiratory and skin diseases was reported. A high rate of the cases being irritable and moody was noticed. Significantly higher gastrointestinal symptoms were also reported among the cases in relation to the controls. The prevalence of pathogenic airborne microorganisms originating from the wastewater treatment plant was reported in high numbers in sampling points close to the wastewater treatment plant. More analytical epidemiological investigations are needed to determine the cause as well as the burden of the diseases to inhabitants living surrounding the wastewater treatment plant.

Simulation of the Impact of Higher Ammonia Recycle Loads Caused by Upgrading Anaerobic Sludge Digesters

2005 ◽  
Vol 40 (4) ◽  
pp. 491-499 ◽  
Author(s):  
Jeremy T. Kraemer ◽  
David M. Bagley
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Treatment Plant ◽  
Anaerobic Sludge ◽  
Content Increase ◽  
Limited Information ◽  
Dynamic Simulations ◽  
Treatment Train ◽  
Temperature Liquid ◽  
The Impact

Abstract Upgrading conventional single-stage mesophilic anaerobic digestion to an advanced digestion technology can increase sludge stability, reduce pathogen content, increase biogas production, and also increase ammonia concentrations recycled back to the liquid treatment train. Limited information is available to assess whether the higher ammonia recycle loads from an anaerobic sludge digestion upgrade would lead to higher discharge effluent ammonia concentrations. Biowin, a commercially available wastewater treatment plant simulation package, was used to predict the effects of anaerobic digestion upgrades on the liquid train performance, especially effluent ammonia concentrations. A factorial analysis indicated that the influent total Kjeldahl nitrogen (TKN) and influent alkalinity each had a 50-fold larger influence on the effluent NH3 concentration than either the ambient temperature, liquid train SRT or anaerobic digestion efficiency. Dynamic simulations indicated that the diurnal variation in effluent NH3 concentration was 9 times higher than the increase due to higher digester VSR. Higher recycle NH3 loads caused by upgrades to advanced digestion techniques can likely be adequately managed by scheduling dewatering to coincide with periods of low influent TKN load and ensuring sufficient alkalinity for nitrification.

The Impact of a Chemostat Discharge Containing Oil Degrading Bacteria on the Biological Kinetics of a Refinery Activated Sludge Process

1988 ◽  
Vol 20 (11-12) ◽  
pp. 131-136 ◽  
Author(s):  
A. D. Wong ◽  
C. D. Goldsmith
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Waste Treatment ◽  
Treatment Plant ◽  
Utilization Rate ◽  
Activated Sludge Process ◽  
Kinetic Evaluation ◽  
Degrading Bacteria ◽  
Waste Treatment Plant ◽  
The Impact

The effect of discharging specific oil degrading bacteria from a chemostat to a refinery activated sludge process was determined biokinetically. Plant data for the kinetic evaluation of the waste treatment plant was collected before and during treatment. During treatment, the 500 gallon chemostatic growth chamber was operated on an eight hour hydraulic retention time, at a neutral pH, and was fed a mixture of refinery wastewater and simple sugars. The biokinetic constants k (days−1), Ks (mg/L), and K (L/mg-day) were determined before and after treatment by Monod and Lineweaver-Burk plots. Solids discharged and effluent organic concentrations were also evaluated against the mean cell retention time (MCRT). The maximum utilization rate, k, was found to increase from 0.47 to 0.95 days−1 during the operation of the chemostat. Subsequently, Ks increased from 141 to 556 mg/L. Effluent solids were shown to increase slightly with treatment. However, this was acceptable due to the polishing pond and the benefit of increased ability to accept shock loads of oily wastewater. The reason for the increased suspended solids in the effluent was most likely due to the continual addition of bacteria in exponential growth that were capable of responding to excess substrate. The effect of the chemostatic addition of specific microbial inocula to the refinery waste treatment plant has been to improve the overall organic removal capacity along with subsequent gains in plant stability.

Practical Guide to Determine the Impact of Radon and Other Radionuclides on Water Treatment Processes

1992 ◽  
Vol 26 (5-6) ◽  
pp. 1255-1264
Author(s):  
K. L. Martins
Keyword(s):  
Activated Carbon ◽  
Water Treatment ◽  
Environmental Protection Agency ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Packed Tower ◽  
Treatment Processes ◽  
Radioactivity Exposure ◽  
The Impact ◽  
Percent Removal

During treatment of groundwater, radon is often coincidentally removed by processes typically used to remove volatile organic compounds (VOCs)-for example, processes such as liquid-phase granular activated carbon (LGAC) adsorption and air stripping with vapor-phase carbon (VGAC). The removal of radon from drinking water is a positive benefit for the water user; however, the accumulation of radon on activated carbon may cause radiologic hazards for the water treatment plant operators and the spent carbon may be considered a low-level radioactive waste. To date, most literature on radon removal by water treatment processes was based on bench- or residential-scale systems. This paper addresses the impact of radon on municipal and industrial-scale applications. Available data have been used todevelop graphical methods of estimating the radioactivity exposure rates to facility operators and determine the fate of spent carbon. This paper will allow the reader to determine the potential for impact of radon on the system design and operation as follows.Estimate the percent removal of radon from water by LGAC adsorbers and packed tower air strippers. Also, a method to estimate the percent removal of radon by VGAC used for air stripper off-gas will be provided.Estimate if your local radon levels are such that the safety guidelines, suggested by USEPA (United States Environmental Protection Agency), of 25 mR/yr (0.1 mR/day) for radioactivity exposure may or may not be exceeded.Estimate the disposal requirements of the waste carbon for LGAC systems and VGAC for air stripper “Off-Gas” systems. Options for dealing with high radon levels are presented.

Comparison of lime and alum as oily sludge conditioners

1997 ◽  
Vol 36 (12) ◽  
pp. 117-124 ◽  
Author(s):  
Tay Joo Hwa ◽  
S. Jeyaseelan
Keyword(s):  
Specific Resistance ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Oily Sludge ◽  
Sludge Dewatering ◽  
Capillary Suction ◽  
Sludge Cake ◽  
Solids Content ◽  
Optimum Chemical

Chemical conditioning improves sludge dewatering. Choice of chemical conditioners is very much dependent on the characteristics of the sludges and the type of dewatering devices. Lime, alum, ferric chloride and polyelectrolytes are commonly used chemical conditioners. Anaerobic digested sludge samples collected from a sewage treatment plant with different oil contents varying from 1.8% to 8.0% by weight have been examined in the laboratory to find out their specific resistance, capillary suction time and filter yield. Lime and alum were used separately as conditioners. Different dosages of conditioner varying from 2% to 12% by weight were used to determine the optimum chemical dosage for varying oil contents. Lime dosages of about 6% were found to yield favourable characteristics. Addition of alum decreases the specific resistances and capillary suction times of oily sludges rapidly up to 4% dosages. Alum dosages beyond 4% only increase the solids content in the sludge cake and increase the sludge volume to be handled. A correlation between CST and specific resistance to filtration was established. CST can be measured easily and quickly in the laboratories. Using the CST and the correlation a quick prediction on dewaterability can be established.

Optimisation and control of the inflow to a wastewater treatment plant using integrated modelling tools

1998 ◽  
Vol 37 (1) ◽  
pp. 347-354 ◽  
Author(s):  
Ole Mark ◽  
Claes Hernebring ◽  
Peter Magnusson
Keyword(s):  
Wastewater Treatment ◽  
Real Time ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Pilot Project ◽  
Integrated Modelling ◽  
Real Time Control ◽  
Sewer System ◽  
Time Control ◽  
The Impact

The present paper describes the Helsingborg Pilot Project, a part of the Technology Validation Project: “Integrated Wastewater” (TVP) under the EU Innovation Programme. The objective of the Helsingborg Pilot Project is to demonstrate implementation of integrated tools for the simulation of the sewer system and the wastewater treatment plant (WWTP), both in the analyses and the operational phases. The paper deals with the programme for investigating the impact of real time control (RTC) on the performance of the sewer system and wastewater treatment plant. As the project still is in a very early phase, this paper focuses on the modelling of the transport of pollutants and the evaluation of the effect on the sediment deposition pattern from the implementation of real time control in the sewer system.

Impacts of separate rejection water treatment on the overall plant performance

2003 ◽  
Vol 48 (4) ◽  
pp. 139-146 ◽  
Author(s):  
B. Wett ◽  
J. Alex
Keyword(s):  
Water Treatment ◽  
Treatment Plant ◽  
Operating Experience ◽  
Plant Performance ◽  
High Tech ◽  
State Variables ◽  
Total N ◽  
Unit Process ◽  
Innovative Tool ◽  
The Impact

A separate rejection water treatment appears as a high-tech unit process which might be recommendable only for specific cases of an upgrading of an existing wastewater treatment plant. It is not the issue of this paper to consider a specific separate treatment process itself but to investigate the influence of such a process on the overall plant performance. A plant-wide model has been applied as an innovative tool to evaluate effects of the implemented sidestream strategy on the mainstream treatment. The model has been developed in the SIMBA environment and combines acknowledged mathematical descriptions of the activated sludge process (ASM1) and the anaerobic mesophilic digestion (Siegrist model). The model's calibration and validation was based on data from 5 years of operating experience of a full-scale rejection water treatment. The impact on the total N-elimination efficiency is demonstrated by detailed nitrogen mass flow schemes including the interactions between the wastewater and the sludge lane. Additionally limiting conditions due to dynamic N-return loads are displayed by the model's state variables.

Stock Market Volatility and Terrorism: New Evidence from the Markov Switching Model

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Faheem Aslam ◽  
Hyoung-Goo Kang ◽  
Khurrum Shahzad Mughal ◽  
Tahir Mumtaz Awan ◽  
Yasir Tariq Mohmand
Keyword(s):  
Stock Market ◽  
Significant Risk ◽  
Market Volatility ◽  
Terrorist Attacks ◽  
Stock Market Volatility ◽  
Markov Switching Model ◽  
Physical Damage ◽  
Stock Market Returns ◽  
Switching Model ◽  
The Impact

AbstractTerrorism in Pakistan poses a significant risk towards the lives of people by violent destruction and physical damage. In addition to human loss, such catastrophic activities also affect the financial markets. The purpose of this study is to examine the impact of terrorism on the volatility of the Pakistan stock market. The financial impact of 339 terrorist attacks for a period of 18 years (2000–2018) is estimated w.r.t. target type, days of the week, and surprise factor. Three important macroeconomic variables namely exchange rate, gold, and oil were also considered. The findings of the EGARCH (1, 1) model revealed that the terrorist attacks targeting the security forces and commercial facilities significantly increased the stock market volatility. The significant impact of terrorist attacks on Monday, Tuesday, and Thursday confirms the overreaction of investors to terrorist news. Furthermore, the results confirmed the negative linkage between the surprise factor and stock market returns. The findings of this study have significant implications for investors and policymakers.

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