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The function of cation-binding agents in the enzymatic treatment of municipal sludge.

Wawrzynczyk, Joanna LU ; Recktenwald, Michael LU ; Norrlöw, Olof LU and Dey, Estera LU (2008) In Water Research 42(6-7). p.1555-1562
Abstract
Treatment of sludge with enzymes has previously been shown to efficiently release organic matter. However, the added enzymes were partially adsorbed to, entrapped by or bound to the sludge structure. Simultaneous decrease of enzymes activities was observed. Reduced adsorption and more effective, lower, enzyme dose was achieved in sludge pre-treated with three cation-binding agents. The enzymatic solubilisation of sludge was improved by 150%, 240% and 290%, by 50mM sodium tripolyphosphate (STPP), 25mM citric acid (CA) or 50mM ethylenediaminetetraacetate (EDTA), respectively. With cation binders, the lower relative enzyme dose 0.2 (13.7mg/g total solids (TS)) released 3.5 times higher COD than enzyme dose 1 (68.5mg/g TS) alone. In the... (More)
Treatment of sludge with enzymes has previously been shown to efficiently release organic matter. However, the added enzymes were partially adsorbed to, entrapped by or bound to the sludge structure. Simultaneous decrease of enzymes activities was observed. Reduced adsorption and more effective, lower, enzyme dose was achieved in sludge pre-treated with three cation-binding agents. The enzymatic solubilisation of sludge was improved by 150%, 240% and 290%, by 50mM sodium tripolyphosphate (STPP), 25mM citric acid (CA) or 50mM ethylenediaminetetraacetate (EDTA), respectively. With cation binders, the lower relative enzyme dose 0.2 (13.7mg/g total solids (TS)) released 3.5 times higher COD than enzyme dose 1 (68.5mg/g TS) alone. In the presence of 25mM CA, 75% added protease remained soluble. In the presence of 50mM CA, EDTA or STPP, 50% of alpha-amylase and cellulase remained soluble. At 200mM STPP, alpha-amylase was inactive, and the efficiency of enzymatic sludge hydrolysis decreased. CA was the most effective of the three cation-binding agents tested. It is biodegradable and can be produced endogenously by the microorganisms in sludge. CA has the greatest potential for the practical application to enhance biogas production. This paper reports on the possible mechanisms of enzymes adsorption to the sludge matrix and possible methods of decreasing the adsorption. We suggest that steric hindrances were responsible for the decreased enzymatic sludge solubilisation and that polyvalent metal ions were directly involved in adsorption of enzymes to sludge matrix. The addition of cation binders eliminated both phenomena and thereby improved the enzymatic solubilisation of sludge. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Water Research
volume
42
issue
6-7
pages
1555 - 1562
publisher
Elsevier
external identifiers
  • pmid:18054984
  • wos:000255166600022
  • scopus:40849111919
ISSN
1879-2448
DOI
10.1016/j.watres.2007.11.004
language
English
LU publication?
yes
id
25aa895c-9743-46fd-afe3-677ae7926f15 (old id 1035694)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/18054984?dopt=Abstract
date added to LUP
2009-07-27 15:07:10
date last changed
2017-07-23 04:25:39
@article{25aa895c-9743-46fd-afe3-677ae7926f15,
  abstract     = {Treatment of sludge with enzymes has previously been shown to efficiently release organic matter. However, the added enzymes were partially adsorbed to, entrapped by or bound to the sludge structure. Simultaneous decrease of enzymes activities was observed. Reduced adsorption and more effective, lower, enzyme dose was achieved in sludge pre-treated with three cation-binding agents. The enzymatic solubilisation of sludge was improved by 150%, 240% and 290%, by 50mM sodium tripolyphosphate (STPP), 25mM citric acid (CA) or 50mM ethylenediaminetetraacetate (EDTA), respectively. With cation binders, the lower relative enzyme dose 0.2 (13.7mg/g total solids (TS)) released 3.5 times higher COD than enzyme dose 1 (68.5mg/g TS) alone. In the presence of 25mM CA, 75% added protease remained soluble. In the presence of 50mM CA, EDTA or STPP, 50% of alpha-amylase and cellulase remained soluble. At 200mM STPP, alpha-amylase was inactive, and the efficiency of enzymatic sludge hydrolysis decreased. CA was the most effective of the three cation-binding agents tested. It is biodegradable and can be produced endogenously by the microorganisms in sludge. CA has the greatest potential for the practical application to enhance biogas production. This paper reports on the possible mechanisms of enzymes adsorption to the sludge matrix and possible methods of decreasing the adsorption. We suggest that steric hindrances were responsible for the decreased enzymatic sludge solubilisation and that polyvalent metal ions were directly involved in adsorption of enzymes to sludge matrix. The addition of cation binders eliminated both phenomena and thereby improved the enzymatic solubilisation of sludge.},
  author       = {Wawrzynczyk, Joanna and Recktenwald, Michael and Norrlöw, Olof and Dey, Estera},
  issn         = {1879-2448},
  language     = {eng},
  number       = {6-7},
  pages        = {1555--1562},
  publisher    = {Elsevier},
  series       = {Water Research},
  title        = {The function of cation-binding agents in the enzymatic treatment of municipal sludge.},
  url          = {http://dx.doi.org/10.1016/j.watres.2007.11.004},
  volume       = {42},
  year         = {2008},
}