NOTIFICATION: The Technology Channels will be discontinued on July 31.
Click here to download complimentary copies of Fastmarkets RISI’s pulp and paper newsletters.

 

Kidney stones: A problem not only for people Part II

Read so far

Kidney stones: A problem not only for people Part II

October 17, 2011 - 01:20
Posted in:

BRUSSELS, Oct. 17, 2011 (RISI) -Mills routinely face the problem of calcium oxalate precipitation during the pulping process, the same compound found in kidney stones. With more closed systems and pressure to reduce water consumption, the risks increase. A new project using degrading enzymes may provide some help. Read Part Ihere.
Sandra Winestrand, Leif Jönsson and Anders Sjöde: Sandra and Anders have both done their PhD theses on the calcium oxalate problem

Some comments from the experts participating in this project:

Nils-Olof Nilvebrant, Associate Professor, Borregaard:

How serious is the calcium oxalate problem?
Many mills having problems due to gypsum precipitations have big oxalate problems without knowing it.

Has this project brought the problem closer to its solution?
Yes as we now have a supplier who can produce an enzyme that works in an industrial reality, but the investment still has to be settled on basis of profitability.

What should the next step be?
That Novozymes will invest, i.e. that they trust the opportunity to earn more money on this enzyme than on other enzymes they develop.

Eva Wackerberg, Section Manager Bleaching and Fibre Department at EKA Chemicals:

Why is EKA Chemicals interested in this problem?
EKA Chemicals manufactures some of the chemicals used in bleaching of pulp. Bleaching is a contributing cause to oxalate present in the pulp mill. Another cause is the wood raw material where, for example, aspen is a contributor. As bleaching contributes to the formation of oxalate, which can cause problems for our customers, it is also in our interest to find a solution.

Has the project brought the problem closer to a solution?
If the enzymes that Novozymes have developed become commercially available, we have most likely found a solution to this problem. The project has also contributed to increased knowledge about oxalate generation and the factors influencing the risk for precipitations. In certain cases this knowledge can be enough to solve the problem.

What should the mills do and what can you as a supplier do to minimise or eliminate the problem?
Knowledge about the formation of calcium oxalate has given the mills, as well as us suppliers, increased knowledge which in some cases makes it possible to handle backwater and process conditions in a way so that the precipitation problem can be dealt with. Reduced fresh water use, introduction of chalk and converting to neutral systems in combination with increased brightness demands will lead to increased precipitation problems in the future. This will of course lead to more mills having to be able to degrade the oxalates.

Other comments?
It was difficult to find mills with pronounced problems, maybe due to the fact that they earlier cured the problem by using more fresh water. Perhaps also other problems show up when closing process systems. A remaining aspect to be seen is how durable the enzymes are in full scale production.

Which should be the next step?
Our expectations are that there will be an enzyme on the market able to prohibit precipitations. A longer full scale trial at a customer is needed to strengthen the results achieved in this project.

Pierre Cassland, Senior Research Scientist, Novozymes:

Why is Novozymes interested in this problem?
Today Novozymes produces enzymes for a range of applications within the pulp and paper industry, like e.g. fiber modification and pitch control. Increased closure of water circuits and switching to more environmentally sound bleaching processes contribute to increasingly difficult calcium oxalate precipitation problems in the pulp and paper industry. Within this project, Novozymes could contribute and develop an enzymatic method to solve the problem of oxalate scaling and thereby have the opportunity to widen our product portfolio serving the pulp and paper industry.

How has the project brought the problem closer to a solution?
It has identified new enzymes which, under common mill conditions, can degrade oxalic acid in the process water from different pulp and paper industries and thereby prevent scaling.

How do you see the opportunities that enzyme technology can reduce or even eliminate the oxalate precipitations?
Laboratory results have so far been very promising, but full scale trials are needed before we can give an authoritative answer whether enzymes can be used to solve the calcium oxalate problems. If the pulp and paper industry shows a great interest in the enzymatic solution and if we get positive results in full scale trials, Novozymes will probably start producing this enzyme on a large scale.

Leif Jönsson, Professor at the Department of Chemistry, Umeå University:

How serious is the calcium oxalate problem?
This problem in the pulp and paper industry could actually be bigger than our study indicates as precipitations are not always investigated and can hence be related to calcium oxalate. As there is a tendency that tougher environmental demands increase the calcium oxalate problem, its extent may increase in the future as the environmental demands will not be more lenient.

How has this project brought the problem closer to a solution?
Technically, the project has been a success and the goals were achieved. Economic and market related considerations remain and make it difficult to say whether the technology will be commercialised or not.

Which should the next step be?
We hope that industrial enzyme manufacturers as well as the pulp and paper industry will see the opportunities that this project has pointed out and investigate the potential further. In the meantime we are studying the usage of oxalate degrading enzymes in the food industry, where certain problems and opportunities with oxalic acid and oxalic acid degrading enzymes also can be identified.