The roles of microbes in the removal and inactivation of viruses in a biological wastewater treatment system

1996 ◽  
Vol 33 (10-11) ◽  
pp. 243-250 ◽  
Author(s):  
Tae-Dong Kim ◽  
Hajime Unno
Keyword(s):  
Activated Sludge ◽  
The Other ◽  
Virus Concentration ◽  
Activated Sludge Process ◽  
Filter Feeder ◽  
Virus Removal ◽  
First Order ◽  
Second Stage ◽  
Strong Filter ◽  
Model Virus

The objective of this research is to clarify the mechanism for virus removal in an activated sludge process. The roles of microbes, i.e. bacteria, protozoa and metazoa, which form activated sludge were investigated using poliovirus as a model virus. In a bacteria cultures, the virus concentration decreased in the first one hour after which no further decrease was observed. This phenomenon is explained by the interaction of bacterial floc and virus where virus was removed by reversible adsorption. On the other hand, in the mixed culture of bacteria and protozoa, or of bacteria and metazoa, the virus removal process was observed to proceed in two first-order processes. In the first stage, virus was removed from the liquid phase by adsorption onto the floc, whereas in the second stage, virus is removed by predation of the other microbes, i.e. protozoa or metazoa. Moreover, the floc-forming ability and the feeding manner of the microbes strongly affected the virus removal. Especially, a filter feeder microbe was more effective in virus removal than a detritus feeder microbe. Among the microbes used in the experiments, P. erythrophthalma which had a large mouth and a strong filter-feeding ability as well as a high floc-forming ability showed the most efficient virus removal.

scholarly journals Unknown Inputs Nonlinear Observer for an Activated Sludge Process

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Feten Smida ◽  
Taoufik Ladhari ◽  
Salim Hadj Saïd ◽  
Faouzi M’sahli
Keyword(s):  
Activated Sludge ◽  
High Gain ◽  
The Other ◽  
Nonlinear Observer ◽  
Dynamics Simulation ◽  
Activated Sludge Process ◽  
Unknown Inputs ◽  
Simulation Results ◽  
Economic Concentration ◽  
Substrate Concentrations

This paper deals with the jointly estimation problem of unknown inputs and nonmeasured states of one altering aerated activated sludge process (ASP). In order to provide accurate and economic concentration measures during aerobic and anoxic phases, a cascade high gain observer (HGO) approach is developed. Only two concentrations are available; the other process’s states are assumed unavailable. The observer converges asymptotically and it leads to a good estimation of the unavailable states which are the ammonia and substrate concentration, as well as a quite reconstruction of the unknown inputs, which are the influent ammonia and the influent substrate concentrations. To highlight the efficiency of the proposed HGO with this MIMO system’s dynamics, simulation results are validated with experimental data.

The effect of low sludge age on wastewater fractionation (SS, SI)

2003 ◽  
Vol 47 (11) ◽  
pp. 203-209 ◽  
Author(s):  
S. Haider ◽  
K. Svardal ◽  
P.A. Vanrolleghem ◽  
H. Kroiss
Keyword(s):  
Activated Sludge ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
The Other ◽  
Second Stage ◽  
Lower Maximum ◽  
The Difference ◽  
Selection Of ◽  
Activated Sludge Systems ◽  
Raw Wastewater

In lab-scale experiments at the 2-stage activated sludge pilot plant of Vienna's central WWTP it is shown that the wastewater soluble COD concentration, which is inert to a sludge with SRT < 1 d (SIA) is about double compared to the SI concentration in sludge with SRT > 10 d (SIB). Unexpectedly the ratio of SIA/SIB is independent of the sludge age between SRTs of 0.4 and 1.0 days. The difference between the two SI fractions is soluble COD that is readily biodegradable by the sludge with SRT > 10 d. However, it is degraded at a lower maximum growth rate. These results comply with earlier results gained with different methods and at different WWTPs. It is hypothesised that very low sludge ages result in a selection of fast growing bacteria, which can utilise only part of the SS in the raw wastewater. The other part of SS therefore remains in the wastewater and can thus be utilised for enhanced denitrification in the second stage. It is still unknown beyond which sludge age the soluble inert COD SIA starts to decrease, finally reaching the value SIB for low loaded systems (SRT > 5 days). From this point on SI and SS are assumed only to depend on the wastewater composition and not on the sludge age. The assumption of the Activated Sludge Model No.1 that the biodegradable fractions can be modelled as a single substrate and by a single removal kinetic (one Monod term) appears not to be applicable for low sludge ages. Some suggestions for mathematical modelling, design and operation of 2-stage activated sludge systems are given.

Effect of sludge type on poliovirus association with and recovery from sludge solids

1981 ◽  
Vol 27 (3) ◽  
pp. 279-287 ◽  
Author(s):  
Oscar C. Pancorbo ◽  
Phillip R. Scheuerman ◽  
Samuel R. Farrah ◽  
Gabriel Bitton
Keyword(s):  
Activated Sludge ◽  
The Other ◽  
Virus Concentration ◽  
Poliovirus Type ◽  
Virus Adsorption ◽  
The Mean ◽  
Degree Of Association ◽  
Aerobic Sludge ◽  
Aerobically Digested

Sludge type was found to affect the degree of association between seeded poliovirus type 1 (LSc) and sludge solids. The mean percent of solids-associated viruses for activated sludge mixed liquors, anaerobically digested sludges, and aerobically digested sludges was 57.2, 70.4, and 94.7, respectively. The degree of association between poliovirus and sludge solids was significantly greater for aerobically digested sludges than for the other two sludge types. Sludge solids associated viruses were eluted using 0.05 M glycine buffer, pH 10.5–11.0, and subsequently concentrated by organic flocculation. The effectiveness of the glycine method in the recovery of solids-associated viruses was also found to be affected by sludge type. Significantly lower mean poliovirus recovery was found for aerobically digested sludges (14.5%) than for mixed liquors or anaerobically digested sludges (72.3 and 60.2%, respectively). The eluent used in the method was not as effective in dissociating the virus from aerobic sludge solids as it was for the other two sludge types. All other virus adsorption–elution steps of the method (i.e., virus concentration steps) were equally effective in poliovirus recovery for all three sludge types. It is suggested that future methods developed for the recovery of viruses from sludges be evaluated for the various sludge types likely to be tested.

An activated sludge process without excess sludge production

1997 ◽  
Vol 36 (11) ◽  
pp. 163-170 ◽  
Author(s):  
Yoshio Sakai ◽  
Tetsuro Fukase ◽  
Hidenari Yasui ◽  
Masahide Shibata
Keyword(s):  
Activated Sludge ◽  
Municipal Wastewater ◽  
The Other ◽  
Aeration Tank ◽  
Activated Sludge Process ◽  
Organic Substances ◽  
Complete Elimination ◽  
Excess Sludge ◽  
Effluent Quality ◽  
Inorganic Substances

An activated sludge process which produces no excess sludge was developed. The process is very simple as a small amount of return sludge is ozonated and then returned to the aeration tank. The ozonation enhances biodegradability of activated sludge, which is biologically oxidized in the aeration tank. A full-scale plant for treating 450m3/d of municipal wastewater was constructed and has been operated successfully for 9 months. The amount of excess sludge eliminated is directly proportional to the amount of ozone dosed to the sludge. At the ozone dosing rate of 0.034 kg/kg-SS, complete elimination of excess sludge has been achieved when 4 times more amount of sludge is ozonated than that of the excess sludge expected in the treatment without ozonation. After 5 months of operation without any withdrawal of excess sludge, small amount of inorganic substances like sand and silt accumulated in the sludge. On the other hand, inert organic substances does not seem to accumulate. As for effluent quality, BOD and nitrogen were kept good. Although effluent SS was 2–15 mg/l higher compared to a control without ozonation, it has been well below the discharge limit.

Kinetics of Polymeric Substrate Removal by Activated Sludge: Hydrolysis of Polymers is the Rate-Determining Step

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2457-2460 ◽  
Author(s):  
Y. Ubukata
Keyword(s):  
Amino Acids ◽  
Activated Sludge ◽  
Heterotrophic Bacteria ◽  
Removal Rate ◽  
Peptide Bond ◽  
Activated Sludge Process ◽  
First Order ◽  
Rate Determining Step ◽  
First Order Kinetics ◽  
Hydrolysis Of

A large portion of organic matter in primary effluent is polymers such as proteins and polysaccharides, and heterotrophic bacteria can directly take up only monomers such as amino acids and glucose that are produced from polymers by hydrolysis. Therefore it is assumed that the hydrolysis of polymers to monomers is the rate-determining step in activated sludge process. Activated sludges were acclimated to dextrin or peptone, and polymers (dextrin or peptone) and monomers (glucose or a mixture of free amino acids) were used as substrates for kinetics tests. Monomers were removed linearly, and the removal of polymers followed pseudo first order kinetics on the other hand. The removal rate of monomers was higher than that of polymers. The only one difference between polymer and monomer is whether glycosidic or peptide bond exists in molecule or not. It was, therefore, verified that the hydrolysis of polymer to monomer was the rate-determining step in activated sludge process. The removal of polymers followed apparently first order kinetics at higher F/M ratios, but followed nth (n>l) order kinetics at lower F/M ratios.

Pilot Regulation to Treat PTA Wastewater

2013 ◽  
Vol 295-298 ◽  
pp. 1115-1119
Author(s):  
Lei Shi ◽  
Xue Tan ◽  
Ya Zong Mai
Keyword(s):  
Activated Sludge ◽  
Manganese Peroxidase ◽  
Terephthalic Acid ◽  
Loading Rate ◽  
Specific Activity ◽  
The Other ◽  
Activated Sludge Process ◽  
Purified Terephthalic Acid ◽  
Functional Strain

In the pilot research for treatment of the purified terephthalic acid (PTA) wastewater with the functional strain Fhhh in the carrier activated sludge process (CASP) effectively, control of the value of COD: TN: TP and the concentrations of Cu, Mn, Se and Zn were conducted to improve the manganese peroxidase (MnP) level. When the value of COD:TN:TP was 100:0.36:0.15 and the concentrations of Cu, Mn, Se and Zn were 0.54, 5.07, 0.00 and 0.08mg/L, the specific activity value of MnP reached a higher level being 689 units while the sludge loading rate was 1.09 d-1. This value of the sludge loading rate was those of 4-7fold of the other processes reported. The data suggested that improving MnP level could enhance the degradability for Fhhh. And the potentials for Fhhh in the PTA wastewater CASP will be also discussed in this paper.

On-Line Diagnosis of Do-Probe Condition in the Activated Sludge Process

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2413-2416 ◽  
Author(s):  
H. Spanjers ◽  
G. Olsson
Keyword(s):  
Activated Sludge ◽  
Time Constant ◽  
Time Interval ◽  
Aeration Tank ◽  
Activated Sludge Process ◽  
First Order ◽  
On Line ◽  
Do Concentration ◽  
Probe Condition ◽  
Probe Response

The dissolved oxygen (DO) probe is repeatedly subjected to a step change of the oxygen concentration with a time interval of 15-30 s. For this purpose an existing measuring technique was used in which the activated sludge was sampled continuously from the aeration tank. At each step the time constant of the probe response is estimated which provides a continuous diagnosis of the probe condition. Therefore the DO concentration measurements along the response are fitted to a first order response model of the probe. It was shown that the probe response time constant is a useful indicator for fouling of the probe membrane.

A Study of Fibre Media Submerged Biological Aerated Filter-Activated Sludge Process (FM-AS) for Sewage Treatment

1993 ◽  
Vol 27 (5-6) ◽  
pp. 413-423 ◽  
Author(s):  
Shi. Han-Chang ◽  
V. K. Thomas
Keyword(s):  
Activated Sludge ◽  
Sewage Treatment ◽  
Cost Effective ◽  
Activated Sludge Process ◽  
Biological Aerated Filter ◽  
Dissolved Air Flotation ◽  
Separation Unit ◽  
Second Stage ◽  
Aerated Filter ◽  
Two Stages

The FM-AS process is a two-stage aerobic process consisting of a submerged biological aerated filter packed with fibre media as the first stage and activated sludge as the second stage. A separation unit working on the principle of dissolved-air flotation is needed between the two stages to remove the solids and thereby maintain a suitable sludge age for nitrification in the second stage. The FM-AS process produces effluents with good qualities. The highest removal efficiencies, obtained with a hydraulic retention time of 4.6 hrs. and an operating temperature of 16°C, for BOD5. NH3-N and SS were 95%, 95% and 90% respectively. The economic evaluation suggests that the FM-AS process can be more cost effective than the traditional activated sludge process, particularly when used for upgrading.

Assessment of virus removal by a multi-stage activated sludge process

1976 ◽  
Vol 10 (5) ◽  
pp. 413-420 ◽  
Author(s):  
R.S. Safferman ◽  
Mary-Ellen Morris
Keyword(s):  
Activated Sludge ◽  
Activated Sludge Process ◽  
Virus Removal ◽  
Multi Stage
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