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COMPARISON OF DIFFERENT METHODS FOR ANAEROBIC TREATMENT OF DILUTE WASTEWATERS P. M. Heertjes, Professor and R. R. van der Meer, Engineer Laboratory of Chemical Engineering Delft University of Technology Delft, The Netherlands INTRODUCTION The fact that anaerobic bacteria are able to convert a large variety of organic substrates has been used in wastewater treatment for the stabilization of primary and secondary sludges and for the purification of the wastewater itself [1,2]. The second process is the subject of the study presented in this chapter. This process has been studied intensively with respect to its microbiological and kinetic aspects [3-7], but there is stdl a lack of general technological knowledge, although many technological studies have been performed [8-20]. These studies were mostly undertaken to find out whether the anaerobic process was appropriate for treatment of a specific wastewater. However, no systematic studies were performed to obtain information about the best type of reactor and method of process performance for anaerobic treatment. Because such information would be very useful, a comparative systematic study was set-up with two methods of process performance in three different types of reactor. The types and methods to be studied were chosen according to the conclusions of a literature study performed as an introduction to the experiments. LITERATURE SURVEY Methods of process-performance For anaerobic treatment of wastewater two methods have to be considered: 1. The process-performance in which the conversion of the waste into fatty acids and these into me thane and carbon dioxide take place in one reactor. In this case the acid-forming bacteria and the methane-forming bacteria live and grow under the same circumstances. This process will further be called the "one-reactor process." 2. The process-performance in which the reactions of the waste with the acid-forming bacteria and thereafter of the products (mainly fatty acids) with methane forming bacteria take place in separate reactors. In that case the effluent of the reactor in which acid formation takes place is used as the influent of the reactor for the second step of the process. This process will further be called the "two-reactor process." In general, the bacterial population for biological wastewater treatment adapts itself easdy to changes of the composition, flow and concentration of the wastewater [21-23]. However, the two main groups of bacteria involved in anaerobic treatment do not always adapt themselves with the same rates. This appears from the various examples of anaerobic treatment by the one-reactor process in which the adaptation of the acid-forming bacteria to a change of the influent is too rapid with respect to that of the other bacteria [24-26]. The fatty acids are then produced faster than they can be converted by the methane-forming bacteria, which results in an accumulation of fatty acids and a decrease in pH. Consequently, the methane-forming bacteria wdl be inhibited in their functioning and their adaptation wdl be interrupted. The different adaptation rates of the two groups of bacteria are a consequence of the difference in growth rates. This difference may introduce another problem for the 790
Object Description
Purdue Identification Number | ETRIWC197980 |
Title | Comparison of different methods for anaerobic treatment of dilute wastewaters |
Author |
Heertjes, P. M. Meer, R. R. van der |
Date of Original | 1979 |
Conference Title | Proceedings of the 34th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,30453 |
Extent of Original | p. 790-804 |
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 | 2009-06-24 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page0790 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | COMPARISON OF DIFFERENT METHODS FOR ANAEROBIC TREATMENT OF DILUTE WASTEWATERS P. M. Heertjes, Professor and R. R. van der Meer, Engineer Laboratory of Chemical Engineering Delft University of Technology Delft, The Netherlands INTRODUCTION The fact that anaerobic bacteria are able to convert a large variety of organic substrates has been used in wastewater treatment for the stabilization of primary and secondary sludges and for the purification of the wastewater itself [1,2]. The second process is the subject of the study presented in this chapter. This process has been studied intensively with respect to its microbiological and kinetic aspects [3-7], but there is stdl a lack of general technological knowledge, although many technological studies have been performed [8-20]. These studies were mostly undertaken to find out whether the anaerobic process was appropriate for treatment of a specific wastewater. However, no systematic studies were performed to obtain information about the best type of reactor and method of process performance for anaerobic treatment. Because such information would be very useful, a comparative systematic study was set-up with two methods of process performance in three different types of reactor. The types and methods to be studied were chosen according to the conclusions of a literature study performed as an introduction to the experiments. LITERATURE SURVEY Methods of process-performance For anaerobic treatment of wastewater two methods have to be considered: 1. The process-performance in which the conversion of the waste into fatty acids and these into me thane and carbon dioxide take place in one reactor. In this case the acid-forming bacteria and the methane-forming bacteria live and grow under the same circumstances. This process will further be called the "one-reactor process." 2. The process-performance in which the reactions of the waste with the acid-forming bacteria and thereafter of the products (mainly fatty acids) with methane forming bacteria take place in separate reactors. In that case the effluent of the reactor in which acid formation takes place is used as the influent of the reactor for the second step of the process. This process will further be called the "two-reactor process." In general, the bacterial population for biological wastewater treatment adapts itself easdy to changes of the composition, flow and concentration of the wastewater [21-23]. However, the two main groups of bacteria involved in anaerobic treatment do not always adapt themselves with the same rates. This appears from the various examples of anaerobic treatment by the one-reactor process in which the adaptation of the acid-forming bacteria to a change of the influent is too rapid with respect to that of the other bacteria [24-26]. The fatty acids are then produced faster than they can be converted by the methane-forming bacteria, which results in an accumulation of fatty acids and a decrease in pH. Consequently, the methane-forming bacteria wdl be inhibited in their functioning and their adaptation wdl be interrupted. The different adaptation rates of the two groups of bacteria are a consequence of the difference in growth rates. This difference may introduce another problem for the 790 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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