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Cross-flow filtration of fruit juice
10. Feasibility studies
10.1 The Method.
10.2 The limits
10.3 The different parameters used
10.4 The activity at Vallø Saft.
10.5 The pre-filtration step.
10.6 Feasibility study
over the pre-filtration step.
10.7 The final filtration step.
10.8 Feasibility study
over the final filtration step.
10.9 Conclusion.
In the Feasibility study the Filtomat and crossflow filtration technology will be compared with a traditional vacuumfilter and an ultrafiltration unit. The analyses of the different technologies will be concentrated partly on the effect they have on the environment and partly on their profitability. The Feasibility study is only connected to the first phase of this project. A financially foundation for the second phase has not yet been established.
Objective
According to the project description the feasibility study shall:
 | Analyse whether the crossflow filtration technology in a cycle of live perspective has a positive influence on the environment. |
| Analyse the positive and negative effects the company - Vallø Saft A/S – will experience if they as an alternative to the existing filtration system invested in the Filtomat/crossflow filtration technology. The positive and negative effects it would have on the social aspects should also be considered. |
Compared systems
The following three filtration systems’s effect on the environment and their profitability will be compared In this feasibility study.
1. A traditional filtration system based on pre-treatment consisting of a centrifuge and a Vacuumfilter using perlite. A pressurefilter with kieselguhr as a filteraid is used to the final filtration. This system is at the moment used daily at Vallø Saft A/S
2. A filtration system consisting of the Filtomat filtration technology for the pre-treatment of the juice and a 0,01 m2 crossflow microfiltration unit build at the Technical University of Denmark, Department of Biotechnology, Pilot Plant or the final filtration. Experiments with water on a 1 m2 crossflow microfiltration unit will also be conducted to examine possible shadoweffects
3. A filtration system consisting of the Filtomat filtration technology for the pre-treatment of the juice and a 0,01 m2 crossflow microfiltration unit build at the Technical University of Denmark, Department of Biotechnology, Pilot Plant or the final filtration. Experiments with water on a 1 m2 crossflow microfiltration unit will also be conducted to examine possible shadoweffects.
Figure 10.1. The three filtration systems
A cycle of live perspective will be used to compare the three different filtration systems. In the following the limits of the cycle of live perspective is defined. A general view of the exact parameters connected to the environment and economy will thereafter be presented. The comparison of the three different filtration systems will be based on these parameters.
Phases of the study
The effect the different filtration systems have on the environment will be considered in a cycle of live perspective. It will be relevant to examine the following phases in a filtration technology cycle of live:
Production of the filtration technology
Operation and maintenance of the filtration technology
Dispose of the filtration technology
Production of the filtration technology
In relation to the phase: Production of the filtration technology, the feasibility study will focus on the investment costs (fixed costs) together with the transcription and lifetime of the technology.
Operation and maintenance of the filtration technology
The phase, Operation and maintenance of the filtration technology, is the primary area of the feasibility study. The focus will be on the maintenance and operational input and output for each of the specific filtration technologies. The output here is understood as the product and the by-products such as wastewater and normal waste. The quality of the juice is also a central point, since the new technology must produce a quality which is just as good or better than the one Vallø Saft is achieving by using the traditional pre-treatment filtration system together with either a pressure filter or a ultrafiltration unit.
Dispose of the filtration technology
Finally it shall be stated that it was not found relevant to focus on the phase: Dispose of the filtration technology since the project only consist of experiments concerning operation and maintenance. Phase two in the filtration technology cycle of live is therefore as mentioned the most important and through this the central questions of the feasibility study, will be answered
10.3 The different parameters used
Below the parameters used in relation to the phases: Production of the filtration technology and operation and maintenance of the filtration technology are shown.
The pre-filtration step and the final filtration step will be analysed separately.
Table 10.1. Production of the filtration technology.
| Parameter |
| Investment costs (fixed costs and capacity) |
| The transcription of the investment (year) |
| Lifetime of the technology (years and cost a year/m3). |
Table 10.2. Operation and maintenance of the filtration technology (input)
| Input |
| Parameter |
| Use of energy (kW/h and kW/m3 juice) |
| Cost of energy (Kr/m3 juice) |
| Filtration aid and costs (kg perlite and the purchasing expenses Kr/m3 juice) |
| New water for cleaning (l/m3 and the expenses Kr/m3 juice) |
| Labour cost pr. cleaning (Kr/m3 juice) |
Table 10.3. Operation and maintenance of the filtration technology (output)
| Output |
| Parameter |
| Juice capacity (m3 juice pr. hour) |
| Wastewater from cleaning (l wastewater and the expenses, Kr/m3 juice) |
| Waste (The expenses, Kr/m3juice) |
10.4 The activity at Vallø Saft The following flowsheets show the yearly production of black currant andcherry juice at Vallø Saft and the demands for the new technology. The amounts in the above flowsheets are collected at Vallø Saft. It is very important to underline that the amounts and percents are not precise, but an approximate average based on the amount of berries used in the production over a year. Black currant (BC) and cherry (C) together make up approximately 55 % of the production at Vallø Saft (VS). This project concerns only black currant and cherry juice and the feasibility study will therefore be based upon the above amounts. In the following the fixed and variable cost for the centrifuge/vacuum filtration system and the Filtomat filter unit will stated. 10.6 Feasibility study over the pre-filtration step. In the following the centrifuge/vacuum filtration system and the Filtomat filter unit will be analysed within the limits of the feasibility study. Table 10.7. Total cost
Environmental effects It is clear, when the total cost in the above overview is considered that the Filtomat filter unit in a cycle of life perspective has a positive influence on the environment. The cost of energy for the Filtomat filter is only 0,17 Kr/m3 juice filtrated, which is 15 times less than the centrifuge and 50 times less than the vacuumfilter. Less energy used means less CO2 produced and the reduction of CO2 will contribute to a better environment. The Filtomat filter is not using any filter aid like the vacuumfilter and therefore in this way also attributes to an improvement of the environment, since the filter aid are scattered in the nature. Perlite is however not as dangerous as kieselguhr for the human health. The chemicals for the cleaning of the Filtomat filter is not any better or worse than the one used in the centrifuge and a change to the new technology will therefore not lead to any environment improvement in this aspect. Finally the amount of wastewater from the Filtomat unit is a lot less than what comes from the centrifuge and vacuumfilter, and the reduction in the amount of the wastewater will also have a positive effect on the environment. Economical effects When the economy is considered, it would be an advantage for Vallø Saft to change to the Filtomat filter unit. Both the fixed costs and the variable cost for the new technology are lower. When for example the variable cost is considered, it only cost 1,19 Kr pr. m3 juice filtrated in the Filtomat filter unit. The higher variable costs for the traditional system are especially because of the vacuumfilter, which is using a lot of energy, labour cost and filter aid. The lower cost should give Vallø Saft the possibility to either increase their profit directly or lower the price of their products and thereby increase their share of the marked, which again should increase their profit. All in all the new technology should strengthen Vallø Saft’s position in the market. The downside of the Filtomat filter unit is however that it at the moment can’t fully replace the existing system. Experimental results indicate that the Filtomat unit can filtrate pasteurised black currant to the same quality as juice coming from the vacuumfilter. This is however not the case for sour cherry, which blocks up the Filtomat filter and therefore needs to be treated before it is filtrated in the Filtomat unit. The result for black current is however very interesting, because not only is the centrifuge/vacuum filter step replaced but the clarification step seems not to be necessary either. If this is the case, the new technology will lower the cost of production even more. It will also have a positive effect on the environment since the amount of chemical used and wastewater produced will be lowered. Social effects The society will also benefit from the new technology since it is less harmful towards the environment. The lower production cost should also result in lover prices for the consumers. 10.7 The final filtration step. The fixed and variable cost for the pressfilter, the ultrafiltration unit and the crossflow filtration unit (polymer membranes) will be stated in the following. Table 10.8. Production of the filtration technology Table 10.8. Production of the filtration technology
Tabel 10.10. Operation and maintenance of the filtration technology (output)
1 Price of the wastewater: Tax/year = 200000 Kr, sludge removal/year = 275000 Kr, amount of wastewater: 60000 m3. The price for removal of 1 m3 is: (200000 Kr + 275000 Kr)/60000 m3 = 7,92 Kr.10.8 Feasibility study over the final filtration step. In the following the pressfilter, the ultrafiltration unit and the crossflow filtration united (polymer membranes) will be analysed within the limits of the feasibility study. Tabel 10.11. Total cost
Environmental effects In the cycle of life perspective the crossflow microfiltration unit will have a positive influence on the environment compared to the pressfilter and the ultrafiltration unit. The cost of energy for the crossflow microfiltration unit is only 0,86 Kr pr. m3 juice filtrated, which is 2 times less than the pressfilter and 7 times less than the ultrafiltration unit. Less energy used means less CO2 produced and the reduction of CO2 will contribute to a better environment. The crossflow microfiltration unit is not using any filter aid (kieselguhr) like the pressfilter and in this way it also attributes to an improvement of the environment, since the filter aid are scattered in the nature. Kieselguhr is dangerous for the human health and a change by law in how to handle and dispose of it is believed to come in a near future. The amount of wastewater from the crossflow microfiltration unit is however as high as for the ultrafiltration unit: 3400 m3, which is all most 19 times as much as the pressfilter. It is however believed that the wastewater from the crossflow microfiltration unit can be concentrated and used for animal feed, and it will thereby not damage the environment. The chemicals for the cleaning of the crossflow microfiltration is not any better or worse than the one used in the ultrafiltration unit and a change to the new technology will therefore in this aspect not lead to any environment improvement. Economical effects It would from an economy point of view be an advantage for Vallø Saft to change to the crossflow microfiltration unit. Compared with the ultrafiltration unit it has both lower fixed and variable cost. When compared with the pressfilter the crossflow microfiltration unit has higher fixed costs and lower variable costs. (the price of new filterplates is not included in the fixed cost for the press filter, and the cost is therefore higher than the 9.04 Kr/m3). It is believed that the variable cost for the pressfilter will increase within the next years because of the use of kieselguhr. Compared with the filtration system used today where 65 % is filtered on the ultrafiltration united and 35 % is filtered on the pressfilter the crossflow microfiltration unit is 25 % cheaper. The lower cost should give Vallø Saft the possibility to either increase their profit directly or lower the price of their products and thereby increase their share of the market, which again should increase their profit. All in all the new technology should strengthen Vallø Saft’s position in the market. At the moment the crossflow microfiltration unit can not replace the existing system, but the results indicate that with further development this should be possible. Social effects The society will also benefit from the new technology since it is less harmful towards the environment. The lower production cost should also result in lower prices for the consumers. When the three filtration systems in figure 10.1. are compared, it is clear that the new technology - that is pre-filtration with the Filtomat filter and the final filtration with the crossflow filtration unit - is the best for the environment, this technology also gives the lowest production cost. This system can however not replace the present system at the moment, but with further development this should be possible. |
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