Effect of Suspended Solids on Inactivation of Poliovirus and T2-Phage by Ozone

1989 ◽  
Vol 21 (3) ◽  
pp. 215-219 ◽  
Author(s):  
Mitsumi Kaneko
Keyword(s):  
Activated Sludge ◽  
Contact Time ◽  
Model Equation ◽  
Suspended Solids ◽  
Virus Inactivation ◽  
Large Reduction ◽  
Log10 Reduction ◽  
Applied Dose ◽  
Using Data ◽  
Logarithmic Reduction

This study was conducted to quantify the effects of suspended solids on virus inactivation by ozone and to develop guidelines for ozone dosages in disinfection using poliovirus and T2-phage. The curve of virus count reduction could be divided into three phases: an initial large reduction which occurred within 30 seconds of contact between the viruses and ozone; a subsequent logarithmic reduction; and finally, a slow reduction in response to decreasing ozone concentrations. The reduction of the viruses by ozone is expressed well by the Collins-Selleck Model. The presence of suspended solids significantly reduced the rate of virus inactivation. Using data obtained in this study, the model equation gives the following estimates: if 99.99% inactivation is required with a contact time of 5 minutes, an ozone residual of 0.6 mg/l is necessary when suspended solids are not present; with kaolin levels of 1 and 10 mg/l, ozone residuals of at least 0.9 and 3.7 mg/l, respectively, are necessary for 99.99% inactivation in 5 minutes. If more than 1 mg/l of an autoclaved activated sludge is added to the water, the commonly applied dose of ozone is not sufficient to produce more than a 4 log10 reduction in 5 minutes.

Effects of Suspended Solids on Inactivation of Poliovirus by Chlorine

1983 ◽  
Vol 15 (5) ◽  
pp. 137-143 ◽  
Author(s):  
Mitsumi Kaneko ◽  
Hideko Igarashi
Keyword(s):  
Activated Sludge ◽  
Contact Time ◽  
Suspended Solids ◽  
Residual Chlorine ◽  
Protective Effects ◽  
Beef Extract

Attempts were made to indicate the protective effects of the suspended solids for inactivation of polioviruses in water by chlorine. Solids associated viruses, which were prepared by centrifugation after mixing polioviruses with sterilized kaoline or activated sludge and/or by elution with pH 8, 2% beef extract, were inactivated by chlorine. The activated sludge was found to absorb 96% of total poliovirus added, whereas 74% of the viruses added was absorbed to the kaoline. It has become clear that activated sludge which is porous in structure protects the viruses from inactivation by chlorine more effectively than kaoline does. When the concentration of the virus-containing solids was 10 mg/l, initial residual chlorine of 1.0 mg/l was not enough to get more than 3 log10 viral reduction with 30 minutes contact time. The concentration of 1.0 mg/l could affect inactivation of viruses seriously.

Behaviour of Mechanically Blended Return-Sludge in Absence of Substrate

1970 ◽  
Vol 5 (1) ◽  
pp. 34-54
Author(s):  
Shyam D. Bokil ◽  
Jatinder K. Bewtra
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Aeration Rate ◽  
Batch Experiments ◽  
Sludge Treatment ◽  
Waring Blender ◽  
Settling Characteristics

Abstract Nine sets of batch experiments, each of ten to twelve days duration, were conducted in the laboratory on return-sludge samples collected from activated sludge treatment plant at Windsor. The thickened sludge samples were blended daily in a waring blender and were continuously aerated in twelve-litres capacity jars. Parallel runs were made on control sludge samples which were not blended. Amongst the parameters varied were the speed and frequency of blending and the aeration rate. The effects of these variables on progressive bio-degradation of volatile suspended solids and the settling characteristics of the sludge were determined. Blended sludge showed significant improvement in the rate of bio-degradation and its settling characteristics as compared to the control unblended sludge

The Efficiency of a Biological Activated Sludge Effluent Treatment Plant with Extended Aeration

1988 ◽  
Vol 20 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Rurik Skogman ◽  
Reino Lammi
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Forest Products ◽  
Effluent Treatment ◽  
Chlorinated Phenols ◽  
Forest Products Industry ◽  
Effluent Treatment Plant ◽  
Closed Systems ◽  
Treating Effluent

The requirements imposed on the Finnish forest products industry by the water authorities have focused on the reduction of BOD and suspended solids in the wastewaters. The industry has tried to comply with these requirements, first through internal measures such as process changes and closed systems. When these have not been sufficient, external treatment has been resorted to. The Wilh. Schauman Company in Jakobstad has chosen activated sludge with extended aeration from among the available methods for treating effluent. The plant has operated since the beginning of 1986 with extremely good results. In addition to the reduction of BOD and suspended solids, there has been a marked decrease of chlorinated phenols. Chlorinated substances with higher molecular weight are also removed during the process.

scholarly journals Influent with Particulate Substrate, Clean, Innocuous and Sustainable Solution for Bulking Control and Mitigation in Activated Sludge Process

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 984
Author(s):  
Pedro Cisterna-Osorio ◽  
Claudia Calabran-Caceres ◽  
Giannina Tiznado-Bustamante ◽  
Nataly Bastias-Toro
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Nutrient Deficiency ◽  
Microscopic Analysis ◽  
Volume Index ◽  
Favorable Effect ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Active Sludge ◽  
Chemical Reagents

This research studies the incidence of the type of substrate, soluble or particulate, in the emergence, development, and inhibition of bulking in activated sludge systems. It was evaluated using the sludge volume index (SVI), mixing liquor-suspended solids (MLSS), microscopic analysis of biomass, and effluent suspended solids (ESS). In the first experiment, four sequencing batch reactors (SBRs) were fed with soluble substrate at a fixed mass, while the mass of the particulate substrate varied, as those (saccharose mass/flour mass) ratios were 3:1, 3:2, 3:3 and 3:4., with a deficit ranging from 20 to 30% compared to the ratio recommended. The four SBRs have similar MLSS, IVL, and ESS. From day 30, with a deficit from 80 to 90%, the influents have ratios 1/1 and 1/2 until 48 days. The SBRs present IVL between 600 and 730 mL/g and ESS from 370 to 440 mg/L; unlike influents with ratios 1/3 and 1/4, they present IVL between 170 and 185 mL/g, and ESS from 260 to 270 mg/L. The favorable effect of particulate matter is categorical. In the second set of experiments, two SBRs were studied: SBR 1 fed with saccharose, and SBR 2 with flour; there is a lack of nutrients causing bulking in SBRs. Once the nutrient deficiency condition is changed in day 11 to excess, after 22 days, the SVI was 190 mL/g, ESS was 360 mg/L, and MLSS was 2000 mg/L for influents with saccharose; the influent with flour, with an SVI of 80 mL/g, ESS of 100 mg/L, and MLSS of 4000 mg/L, shows faster and more consistent recovery with the particulate substrate. Therefore, the proposal is to add particulate substrate-like flour to active sludge plants facing bulking. It is a clean, innocuous and sustainable alternative to processes that use chemical reagents.

Evaluating the treatment performance of a full scale Activated Sludge Plant in Islamabad, Pakistan

2012 ◽  
Vol 7 (1) ◽  
Author(s):  
S. S. Fatima ◽  
S. Jamal Khan
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Full Scale ◽  
Operational Parameter ◽  
Mixed Liquor ◽  
Treatment Performance

In this study, the performance of wastewater treatment plant located at sector I-9 Islamabad, Pakistan, was evaluated. This full scale domestic wastewater treatment plant is based on conventional activated sludge process. The parameters which were monitored regularly included total suspended solids (TSS), mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), biological oxygen demand (BOD), and chemical oxygen demand (COD). It was found that the biological degradation efficiency of the plant was below the desired levels in terms of COD and BOD. Also the plant operators were not maintaining consistent sludge retention time (SRT). Abrupt discharge of MLSS through the Surplus Activated sludge (SAS) pump was the main reason for the low MLSS in the aeration tank and consequently low treatment performance. In this study the SRT was optimized based on desired MLSS concentration between 3,000–3,500 mg/L and required performance in terms of BOD, COD and TSS. This study revealed that SRT is a very important operational parameter and its knowledge and correct implementation by the plant operators should be mandatory.

Physicochemical and Biological Treatability Studies on Surfactant Wastewaters

1992 ◽  
Vol 26 (1-2) ◽  
pp. 377-386 ◽  
Author(s):  
F. Çeçen
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Heavy Duty ◽  
Surface Active Agents ◽  
Surface Active ◽  
Liquid Type ◽  
Experimental Findings ◽  
Biological Treatability ◽  
Anionic Surface

Laboratory-scale physicochemical and biological treatability studies were performed on wastewaters discharged from an industry producing household and heavy-duty detergents of powder and liquid type. The characterization of effluents led to the conclusion that the industry was highly pollutant in terms of BOD5, COD, surfactant, phosphorus, oil-grease, suspended solids and pH. By the use of lime in the precipitation stage about 80 % of COD and more than 90 % of phosphorus and anionic surface active agents could be removed. Following the treatment with lime the biodegradation of these wastewaters was investigated in continuously fed activated sludge units. The biokinetic constants of the reaction were determined as k = 0.76 d−1, Ks = 972 mg/l COD, a = 0.58 mg O2/mg COD, b = 0.044 mg O2/mg MLVSS.d. The experimental findings were used in the design of a full-scale treatment system.

scholarly journals Validation of activated sludge plant performance for virus and protozoan reduction

2013 ◽  
Vol 3 (2) ◽  
pp. 140-147 ◽  
Author(s):  
A. R. Keegan ◽  
B. Robinson ◽  
P. Monis ◽  
M. Biebrick ◽  
C. Liston
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Plant Performance ◽  
Log10 Reduction ◽  
Validation Process ◽  
Indicator Microorganisms ◽  
Department Of Health ◽  
Combined Data ◽  
Plant Basis

Validation studies were undertaken at Adelaide metropolitan wastewater treatment plants to establish the actual log10 reduction values (LRVs) of pathogens (viruses and Cryptosporidium) across activated sludge plants (ASPs) as an alternative to accepting the default values attributed by the Department of Health and Ageing (DHA). Grab samples were collected across a 6-week period and assessed for pathogens (adenovirus and Cryptosporidium) and indicator microorganisms (sulphite-reducing clostridia and F-RNA bacteriophage). Through applying the validation process, the DHA has revised the default value for reduction of viruses with an increase from 0.5 log10 to 1 log10 while the value for protozoa remains at 0.5 log10 based on the combined data for a well-operated and maintained ASP. This provides the basis for considering further work at individual plants which may allow higher log credits to be obtained on a plant by plant basis.

Uncertainties of spectral in situ measurements in wastewater using different calibration approaches

2006 ◽  
Vol 53 (12) ◽  
pp. 187-197 ◽  
Author(s):  
L. Rieger ◽  
G. Langergraber ◽  
H. Siegrist
Keyword(s):  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Total Suspended Solids ◽  
Data Sets ◽  
Global Calibration ◽  
Nitrite Nitrogen ◽  
Calibration Methods ◽  
Using Data ◽  
Nitrate And Nitrite

Three calibration methods were applied to UV/VIS spectra recorded in the influent of six wastewater treatment plants (WWTPs) to measure total COD (CODtot), filtered COD (CODfil), nitrate and nitrite nitrogen (NOx-N) and total suspended solids (TSS). It could be shown that a calibration of the sensor using data sets from four Swiss WWTPs leads to an improvement of the precision in comparison to the global calibration provided by the manufacturer. A calibration to the specific wastewater matrix always improves the results and gives the highest accuracy. For CODtot a mean coefficient of variation CVx of 12.5% could be reached, whereas for NOx-N only weak results were achieved (average CVx=36%).

Improving nitrogen removal in predenitrification-nitrification biofilters

2004 ◽  
Vol 48 (11-12) ◽  
pp. 419-428 ◽  
Author(s):  
L. Larrea ◽  
A. Abad ◽  
J. Gayarre
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Nitrogen Removal ◽  
Suspended Solids ◽  
Complete Removal ◽  
Cod Removal ◽  
Nitrification Rate ◽  
Removal Rates ◽  
N Removal ◽  
Activated Sludge Processes

The effect on NH4-N removal rates in nitrification biofilters of filtered biodegradable COD and particulate COD leaving predenitrification biofilters was studied in a lab scale plant configured with the separated system of biofilters for secondary nitrogen removal from urban wastewaters. Applying a typical COD load of 11 kg/m3.day to the predenitrification biofilter and maximizing its COD removal by adding nitrates or by operating an improved control of the internal recycle, only 60% removal of filtered biodegradable COD was found. This value corresponds to the complete removal of the readily biodegradable substrate (30% of influent filtered COD) and 36% of filtered slowly biodegradable substrate (50% of influent COD). The remaining 64% of the latter entered the nitrification biofilter, causing competition between heterotrophs and nitrifiers for dissolved oxygen in the inner layers of the biofilm. Consequently the nitrification rate had relatively low values (0.5 kgN/m3.d) at 14°C despite using dissolved oxygen levels of 6 mg/l. This behaviour may explain the lower nitrification rates obtained in some cases of nitrification biofilters compared to those in tertiary nitrification after activated sludge processes. The particulate COD entering the nitrification biofilter is associated with the suspended solids leaving the denitrification biofilter which are adsorbed by the external layers of the biofilm, increasing its thickness. The activity of the nitrifiers was affected because of a lack of oxygen when the thickness was left to grow considerably. Therefore no significant particulate COD effect is expected to occur as long as backwashing is carried out with the appropriate frequency.

The Infuence of the Depth of the Secondary Sedimentation Tanks on the Sedimentation Efficiency at Bromma Sewage Treatment Plant

1988 ◽  
Vol 20 (4-5) ◽  
pp. 143-152 ◽  
Author(s):  
M. Tendaj-Xavier ◽  
J. Hultgren
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Ferrous Sulphate ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Design Flow ◽  
Activated Sludge Process ◽  
Solids Concentration ◽  
Rapid Flow

Bromma sewage treatment plant is the second largest plant in Stockholm with a design flow of 160,000 m3/d. The wastewater is treated mechanically, chemically by pre-precipitation with ferrous sulphate, and biologically by the activated sludge process. The requirements for the plant are 8 mg BOD7/l, 0.4 mg P/l and 2 mg NH4+-N/l. The requirement for ammonia refers to the period July-October. In order to meet those rather stringent requirements, the biological step was expanded 3 years ago with 6 new sedimentation tanks. The 6 new tanks have the same area as the 6 old ones but they have only a depth of 3.7 m compared with the depth of the old tanks, 5.7 m. Experience from the first years of operation of the new tanks is that these tanks are more sensitive and less efficient than the older ones. It seems that the effluent suspended solids concentration from the old tanks is less influenced by rapid flow variations than the concentration in the effluent from the new secondary sedimentation tanks. During the nitrification period denitrification takes place to some degree in the secondary sedimentation tanks. This may cause loss of solids and it has been observed that the deeper old tanks usually produce an effluent of better quality and seem to be less influenced by denitrification than the new ones.

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