scholarly journals The use of simultaneous chemical precipitation in modified activated sludge systems exhibiting biological excess phosphate removal: Part 5: Experimental periods using a ferrous-ferric chloride blend

Water SA ◽  
2004 ◽  
Vol 27 (2) ◽  
Author(s):  
DW De Haas ◽  
MC Wentzel ◽  
GA Ekama
Keyword(s):  
Activated Sludge ◽  
Ferric Chloride ◽  
Chemical Precipitation ◽  
Phosphate Removal ◽  
Activated Sludge Systems

Phosphate and Nitrogen Removal Programme in The Netherlands

1993 ◽  
Vol 27 (5-6) ◽  
pp. 307-316
Author(s):  
Rob den Engelse
Keyword(s):  
Drinking Water ◽  
The Netherlands ◽  
Activated Sludge ◽  
Nitrogen Removal ◽  
Phosphate Removal ◽  
Market Situation ◽  
Nitrogen And Phosphate Removal ◽  
The Relationship ◽  
Initial Results ◽  
Activated Sludge Systems

A programme of research is being conducted in the Netherlands in the period 1990-1992 to find answers to the questions and solutions to the difficulties involved in the introduction of extensive nitrogen and phosphate removal. The purpose, organisation and implementation of the programme are considered. The most important initial results are set out relating to the clogging of aeration elements on simultaneous phosphate removal in activated sludge systems, to a guide to biological phosphate removal, phosphate stripping, the relationship between softening drinking water and phosphate removal and the market situation for chemicals for phosphate removal.

The Effect of Metallic and Ionic Species on the Performance of a Biological Effluent Treatment System

1977 ◽  
Vol 12 (1) ◽  
pp. 191-212
Author(s):  
B. Volesky ◽  
Q. Samak ◽  
P. Waller
Keyword(s):  
Activated Sludge ◽  
Inorganic Ions ◽  
Industrial Effluents ◽  
Original Data ◽  
Ionic Species ◽  
Threshold Concentration ◽  
Effluent Treatment ◽  
Organic Load ◽  
Metallic Ions ◽  
Activated Sludge Systems

Abstract Review of the available results appearing in the recent literature is presented focusing particularly upon the effects of metallic ions such as Cr, Cu, Zn, Cd, Hg, V, Zn, Ni and Co. Some original data involving the effects of Na are presented and discussed. Development of parameters used in evaluating the influence of toxic or inhibitory species on the mixed microbial population of an activated sludge system is of crucial importance and different techniques employed such as BOD-COD-TOC-removal rates, Oxygen Uptake Rate, and others are discussed, showing relative inadequacy of currently applied assays. From the data available, certain trends can be discerned. There is a definite threshold concentration for each metallic ion, depending on the organic load of the feed. In the order of increasing toxicity to activated sludge systems reflected in lower BOD removals the following metals have been listed as inhibiting factors at concentrations starting from 1 ppm applied on a continuous basis: hexavalent chromium, cobalt, zinc, cadmium, trivalent chromium, copper and nickel. Metals in combination have not been reported to exhibit any significantly different effects as compared to those observed with individually introduced metallic ions. Tolerance of some activated sludge systems to shock loadings by various inorganic ions and metals is reviewed. The conclusions are of particular importance for estimating the performance of biox systems handling industrial effluents which are likely to contain toxic components of inorganic or metallic nature.

On the Problem of “Two-Phase” Activated Sludge

1991 ◽  
Vol 24 (7) ◽  
pp. 59-64 ◽  
Author(s):  
R. W. Szetela
Keyword(s):  
Activated Sludge ◽  
Single Phase ◽  
Phase System ◽  
Two Phase ◽  
Wastewater Treatment Process ◽  
Sludge Stabilization ◽  
Technological Advantage ◽  
In Series ◽  
State Models ◽  
Activated Sludge Systems

Steady-state models are presented to describe the wastewater treatment process in two activated sludge systems. One of these makes use of a single complete-mix reactor; the other one involves two complete-mix reactors arranged in series. The in-series system is equivalent to what is known as the “two-phase” activated sludge, a concept which is now being launched throughout Poland in conjunction with the PROMLECZ technology under implementation. Analysis of the mathematical models has revealed the following: (1) treatment efficiency, excess sludge production, energy consumption, and the degree of sludge stabilization are identical in the two systems; (2) there exists a technological equivalence of “two-phase” sludge with “single-phase” sludge; (3) the “two-phase” system has no technological advantage over the “single-phase” system.

The Use of Anoxic Selectors for the Control of Low F/M Activated Sludge Bulking

1989 ◽  
Vol 21 (6-7) ◽  
pp. 609-619 ◽  
Author(s):  
Y.-J. Shao ◽  
David Jenkins
Keyword(s):  
Organic Matter ◽  
Activated Sludge ◽  
Pilot Plant ◽  
Detention Time ◽  
Substrate Removal ◽  
Batch System ◽  
Sludge Bulking ◽  
N Removal ◽  
Soluble Substrate ◽  
Activated Sludge Systems

Laboratory and pilot plant experiments on anoxic selector activated sludge systems were conducted on two wastewaters in some cases supplemented with nitrate, acetate or glucose. To prevent bulking sufficient anoxic selector detention time and nitrate levels must be available to reduce selector effluent soluble COD to below 100 mg/l and to reduce readily metabolizable organic matter to virtually zero (< 1 mg/l). Soluble COD/NO3-N removal stoichiometry is in the range 6.0-6.7. Selector systems have elevated soluble substrate removal and denitrification rates compared to CSTR systems. These rates are not affected greatly by temperature (20-25°C) for CSTR sludges but are for selector sludges. Upon exhaustion of nitrate in a selector soluble COD leaks out of the activated sludge in significant amounts. Thiothrix sp. and type 021N denitrify only to NO2 and at much slower rates than Zoogloearamigera does to N2. A sequencing batch system provides an optimistic estimate of the SVI that can be obtained by an anoxic selector system.

Performance Stability of Small Biological Chemical Treatment Plants

1990 ◽  
Vol 22 (3-4) ◽  
pp. 275-282
Author(s):  
R. Storhaug
Keyword(s):  
Activated Sludge ◽  
Chemical Treatment ◽  
Chemical Precipitation ◽  
Poor Quality ◽  
Precipitation Process ◽  
Chemical Plants ◽  
Effluent Standards ◽  
Main Portion ◽  
Rotating Biological Contactors ◽  
Number Of Treatment

Biological and chemical treatment plants constitute a main portion of the overall number of treatment plants in Norway. The biological and chemical plants are divided into three process groups, simultaneous precipitation and activated sludge, combined precipitation and rotating biological contactors (RBC) and post precipitation and activated sludge. Aluminium sulphate or ferric chloride are the commonly used flocculants in the chemical precipitation process. Effluent data from 174 Norwegian biological chemical treatment plants are evaluated. Compared to the effluent standards for each process group, post precipitation shows the best performance. On an average these plants have the lowest actual utilization of the design capacity. The most important factors that cause the treatment plants not to meet the effluent standards are, poor quality of the sewer system, improper design of the plant and organizational problems. Satisfactory separation of particles, flow equalization and proper operational management, are the basic demands to achieve low effluent concentrations for tot-P and BOD7.

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