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3 HIGH RATE THERMOPHILIC PRETREATMENT OF HIGH STRENGTH INDUSTRIAL WASTEWATERS Enos L. Stover, President G. Joshua Samuel, Project Engineer THE STOVER GROUP Stillwater, Oklahoma 74076 ABSTRACT Bench-scale treatability studies were performed with both synthetic and actual high strength industrial wastewaters to evaluate the concept of employing high-rate biological thermophilic activated sludge technology with conventional gravity solids/liquid separation as a pretreatment alternative. The thermophilic activated sludge processes were operated at 55°C and 60°C. The major advantage noted compared to lower temperature mesophilic processes was significantly lower sludge production at comparable levels of treatment. The bench-scale studies show promise for conventional activated sludge technology operating under thermophilic conditions for treating high temperature, high strength, or combinations of high temperature high strength industrial wastewaters as a pretreatment alternative under high loading rate (F/M) conditions. INTRODUCTION The autoheated thermophilic aerobic digestion process has been developed for stabilization of waste biological sludges. The primary objective of this process is to operate under thermophilic conditions (40° to 80°C), preferably 50° to 60°C range, without supplemental heat. In order to accomplish this objective, adequate carbon source (volatile suspended solids or chemical oxygen demand) must be supplied to the process. The organic carbon loading can be supplied in either particulate (volatile solids) or soluble COD form. One of the advantages of the thermophilic process is minimal biomass production or yield coefficient which equates to maximum heat generation. Biological heat production as high as 6,300 BTU/lb oxygen utilized has been reported.1"3 In terms of biological volatile suspended solids with an oxygen equivalent of 1.42 lb 02/lb VSS, this equates to about 9,000 BTU/lb VSS destroyed. Therefore, if the VSS or soluble COD loading rates are high enough and proper precautions are designed into the treatment system to manage heat loss, the aerobic thermophilic treatment process can be equally effective for treatment/stabilization of biological waste sludges or high strength industrial wastewaters. The general requirements to maintain appropriate thermophilic temperatures includes sufficient biodegradable organics (volatile solids or soluble COD) to provide heat of oxidation up to 25 to 30 Kcal/liter, an insulated reactor, and adequate mixing and oxygen transfer efficiency to minimize excessive heat loss. The purpose of this paper is to present the results of bench-scale thermophilic activated sludge studies with soluble high-strength wastewaters. MATERIALS AND METHODS A schematic of the bench-scale biological thermophilic activated sludge system used in this study is presented in Figure 1. The aeration tank was a 5.2 liter (liquid volume) Plexiglas reactor. The aeration tank reactor was mixed and aerated with two 4-inch aquarium diffuser stones. The clarifier was a glass clarifier with a liquid volume of 2.6 liters. The wastewater feed was pumped into the aeration tank reactor, and the effluent flowed by gravity to the clarifier. The clarifier effluent flowed by gravity into an effluent collection bottle, and the settled solids were recycled 52nd Purdue Industrial Waste Conference Proceedings, 1997, Ann Arbor Press, Chelsea, Michigan 48118. Primed in U.S.A. 17
Object Description
Purdue Identification Number | ETRIWC199703 |
Title | High rate thermophilic pretreatment of high strength industrial wastewaters |
Author |
Stover, Enos L. Samuel, G. Joshua |
Date of Original | 1997 |
Conference Title | Proceedings of the 52nd Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,20317 |
Extent of Original | p. 17-24 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-11-03 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 17 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | 3 HIGH RATE THERMOPHILIC PRETREATMENT OF HIGH STRENGTH INDUSTRIAL WASTEWATERS Enos L. Stover, President G. Joshua Samuel, Project Engineer THE STOVER GROUP Stillwater, Oklahoma 74076 ABSTRACT Bench-scale treatability studies were performed with both synthetic and actual high strength industrial wastewaters to evaluate the concept of employing high-rate biological thermophilic activated sludge technology with conventional gravity solids/liquid separation as a pretreatment alternative. The thermophilic activated sludge processes were operated at 55°C and 60°C. The major advantage noted compared to lower temperature mesophilic processes was significantly lower sludge production at comparable levels of treatment. The bench-scale studies show promise for conventional activated sludge technology operating under thermophilic conditions for treating high temperature, high strength, or combinations of high temperature high strength industrial wastewaters as a pretreatment alternative under high loading rate (F/M) conditions. INTRODUCTION The autoheated thermophilic aerobic digestion process has been developed for stabilization of waste biological sludges. The primary objective of this process is to operate under thermophilic conditions (40° to 80°C), preferably 50° to 60°C range, without supplemental heat. In order to accomplish this objective, adequate carbon source (volatile suspended solids or chemical oxygen demand) must be supplied to the process. The organic carbon loading can be supplied in either particulate (volatile solids) or soluble COD form. One of the advantages of the thermophilic process is minimal biomass production or yield coefficient which equates to maximum heat generation. Biological heat production as high as 6,300 BTU/lb oxygen utilized has been reported.1"3 In terms of biological volatile suspended solids with an oxygen equivalent of 1.42 lb 02/lb VSS, this equates to about 9,000 BTU/lb VSS destroyed. Therefore, if the VSS or soluble COD loading rates are high enough and proper precautions are designed into the treatment system to manage heat loss, the aerobic thermophilic treatment process can be equally effective for treatment/stabilization of biological waste sludges or high strength industrial wastewaters. The general requirements to maintain appropriate thermophilic temperatures includes sufficient biodegradable organics (volatile solids or soluble COD) to provide heat of oxidation up to 25 to 30 Kcal/liter, an insulated reactor, and adequate mixing and oxygen transfer efficiency to minimize excessive heat loss. The purpose of this paper is to present the results of bench-scale thermophilic activated sludge studies with soluble high-strength wastewaters. MATERIALS AND METHODS A schematic of the bench-scale biological thermophilic activated sludge system used in this study is presented in Figure 1. The aeration tank was a 5.2 liter (liquid volume) Plexiglas reactor. The aeration tank reactor was mixed and aerated with two 4-inch aquarium diffuser stones. The clarifier was a glass clarifier with a liquid volume of 2.6 liters. The wastewater feed was pumped into the aeration tank reactor, and the effluent flowed by gravity to the clarifier. The clarifier effluent flowed by gravity into an effluent collection bottle, and the settled solids were recycled 52nd Purdue Industrial Waste Conference Proceedings, 1997, Ann Arbor Press, Chelsea, Michigan 48118. Primed in U.S.A. 17 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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