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Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Deliverables
In co-operation with institute PTS and KOCH as supplier of membranes and membranes systems for waste water treatment, a membrane step was tested for treating process water of recovering paper mills. Significant elimination rates of high molecular COD compounds, TSS and Turbidity were achieved in the membrane unit. Apart from producing excellent purification results, the anaerobic treatment proved to have positive influence the downstream ultra-filtration. It has been clearly demonstrated that biological pre-treatment increases the retention capability (from 5-10% to 30-45%) of the membranes used. During more than seven months tests were done with an ultrafiltration pilot plant with membranes from type hollow fibre. These tests could confirm the results achieved in Lab-scale testing.
- 30 % of COD reduction
- 99 % of TSS reduction
- 90 % reduction of turbidity
- Normal fluxrates were found out
- Optimisation of operation mode could be done
Cleaning frequency and method are fixed
- High operation stability
- The influence from changes in influent quality are minimal, only as CaCO3-concentration increases, the Ca-scaling gets a very important concern to deal with. The fouling could be controlled by regularly dosing of acid during backflush.
- All information is available to dimension a full scale system. To make ultrafiltration of waste water, pre-treated by anaerobic biological treatment, economically interesting for papermills, it will be necessary to develop a method to reduce the hardness of the waste water before it enters the ultrafiltration.
As a supplier of water treatment plants, PAQUES has developed a new water treatment unit for water softening. For the softening of the effluent, to make the water suitable for reuse, a crystallisation reactor was developed with an inlet construction for industrial application.
The development relates to a reactor for precipitating a substance, such as a salt, from a solution onto a granular material present in the reactor, comprising an essentially cylindrical vessel, a base which closes off the vessel at the bottom and contains a feed for the solution, and a discharge, provided at the top of the vessel, for the treated solution from which the salt has been at least partially removed by precipitation. The base has a chamber, which is essentially concentric with respect to the vessel, and to which the feed for the solution is connected, in which chamber mixing of the solution and the granular material takes place.
In our case, the reactor is used for the precipitation of CaCO3, which is formed after the biological treatment system. CaCO3 originates from the wastepaper that is used as raw material and gets dissolved in the process water under the influence of volatile fatty acids. Once the volatile fatty acids are converted into methane and carbonates, the over saturation of Ca2+ and HCO3 cause CaCO3 precipitation.
The crystallisation reactor guides this process, so that a pelletised form of CaCO3 is produced, which can be utilised for soil conditioner or for flue gas treatment at power stations.
In co-operation with CADAGUA a membrane bioreactor has been installed by KOCH at paper mill SAICA for integrated water treatment in pilot scale. In this context, KOCH, as a supplier of membranes and membrane systems have developed a membrane step for biomass separation in pilot scale, which allows trials on thermophilic conditions. Because of technical problems with the bioreactor, results about the testing with the ultrafiltration pilot plant are only available over a very short period of time. Nevertheless was it possible to achieve significant elimination rates in the membrane unit.
- 60 % of COD reduction
- Less than 90 % of TSS reduction
- Normal operation flux were found out
- First optimisation of the operation mode could be done
- First information about cleaning frequency and method available
- The influence from changes on the biological system are very important, the influent quality was never stable.
Some important data necessary for the dimensioning of a full scale system couldn't be recorded.
To be able to conclude if a membrane bioreactor makes sense in this case, longer tests have to be done with a stable working thermophilic bioreactor.
In co-operation with institute PTS, supplier of water treatment plants PAQUES and recycling paper mill VPK-OUDEGEM, a new integrated biological water treatment unit on thermophilic anaerobic conditions was successfully developed at recycling paper mill VPK-OUDEGEM. Trials were conducted at PTS in small-pilot scale with highly loaded process waters of a Belgian paper mill on its way to full circuit closure. For more than two years in a row, PTS has achieved outstanding biological degradation rates; average: 81 % COD reduction in spite of high sludge loads of up to 1.5 - 2.5 kgCOD/(kgodmd) at temperatures as high as 55 °C.
The promising possibility of anaerobic treatment under thermophilic operation was afterwards confirmed inpilot scale (at 48 - 55 °C) and full scale (at about 45 °C - using IC-reactor of PAQUES) at the paper mill VPK-OUDEGEM.
In co-operation with institute PTS and supplier of water treatment plants PAQUES, a new integrated biological water treatment unit on thermophilic anaerobic conditions (45 °C) was successfully developed at recycling paper mill VPK-OUDEGEM at full scale.
In this context the loading of process water in terms of COD compounds and calcium could be decreased inthe range of 50-60 %. As a result the process stability was significantly improved. That means: Less time of the machine shut down was spend by removing calcium deposits (reduction of maintenance cost). Better dewatering of the paper by the temperature increase and the conductivity decrease so that the PMs could speed up by 4 %. Simultaneously a further circuit closure (less effluent) could be achieved or the production could be increased without negative impact on paper quality and process stability.
Additional membrane step and a softening step were temporarily installed in pilot scale. In terms of the membrane step it has turned out that process water treatment is technically feasible but because of economical reasons it does not pay off at the moment. However fresh water treatment via membrane RO seems to be very promising from the ecological point of view.
A good working ultrafiltation and RO plant can reduce the tap- and groundwater cost by 30 % without technical risks.
Referring to the softening step it has turned out that because of economical reasons it would be a promising technology, however some technical problems remain to be solved.Even after the softening installation the crystallization still goes on and can cause technical problems for the equipment installed afterwards.
Patent EP 109 7908: circuit purification for the papermaking industry.
In co-operation with institute PTS, the supplier of water treatment plants PAQUES has applied for a new integrated biological water treatment concept - PAPER TECHNOLOGY: Different tailor-made water treatment units will be introduced for cleaning partial water streams according to the needs of water consumers.
Due to the good results, a patent was applied for the in-line treatment of process water or effluent from a paper making process, in which this water is subject to at least one anaerobic purification step, an aeration step and a solids separation step. After that, at least two treated water streams of different quality are returned to the paper production process, which streams originate from a different combination of purification steps. These streams can be returned to different points in the production process, depending on the specific water quality required.
Enclosed figure shows how different treatment steps can be put in series for part of the flows, so that the most economic concept can be put together and the investment cost for taking away the last 10-20% of impurities can be limited to certain extend.
Patent PCT/NL01/00857: device and method for cleaning a fluid (membrane unit).
The development relates to a device, in particular suitable for cleaning a fluid, such as water, comprising at least one set of a first membrane cloth and a second membrane cloth, each being permeable to water over substantially their entire length, which membrane cloths are held taut, substantially parallel to one another in a frame, the membrane cloths between them delimiting a movement path for fluid, the cloths being displaceable with respect to one another between a first position, in which the mutually facing surfaces substantially touch one another, and a second position, in which the cloths lie at a distance from one another and the width of the movement path for the fluid is greater than in the first position, in which device at least one of the cloths, onthe side which faces towards the adjacent cloth, is provided with grooves or webs for the purpose of forming channels between the cloths in the longitudinal direction of the cloths, in the first position of the membrane cloths. In our study for optimisation of aerobic treatment by the use of membranes it was shown, that submerged membrane unites offered the best possibilities as far as energy consumption concerns.
However, the investment costs are high and intermittent cleaning can be problematic. Therefore, it was decided by Paques to start its own membrane development to address these problems. The result is a completely new approach, whichwill be published in a few months from now.
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