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Water
Treatment
Bio-based cooling tower water treatment: A sustainable alternative – Part 2
In this 3-part series of articles, ODYSSEE Environnement presents feedback on using a bio-sourced product for anti-scaling treatment in cooling tower water, compared to conventional products.
By Amaury Buvignier, Frédéric Bertrand, Fabrice Chaussec, Xavier Labeille at ODYSSEE Environnement and Logan MANARANCHE at ODYSSEE USA INC.
I. Introduction After highlighting the importance of identifying tracers correlated with the antiscalant effectiveness of a plant extract, we will address the major challenge inherent in using a natural raw material of agricultural origin, namely, the variability in the quality of the supply. We will present the optimization approach of the industrial extraction process, developed by ODYSSEE Environnement, aimed at reducing the environmental impact of ODYLIFE as well as the regulatory limitations regarding the use of bio-sourced chemicals.
II. The lifecycle analysis and ecotoxicity: results and discussion II. 1. Extraction Previous studies have shown that the choice of ecoextraction method affects its yield [ 5 ]. In this new study, the objective is to investigate if the environmental impact of the extraction process can be improved. Two extraction methods were tested: i. Progressive depletion of the raw material and complete renewal of the extraction solvent at each step; ii. Enrichment of the extract by complete renewal of the material to be extracted at each step.
Figure 1 illustrates the two extraction methods described above. In the exhaustion extraction method, the solvent is renewed at each stage, while in the enrichment extraction method, it is the dry matter that is renewed at each step. Regardless of the method or extraction step, the Solid / Liquid ratio is 10 % by mass. Figure 2 shows the evolution, step by step, of various parameters measured during an exhaustion extraction( a) and( b) and during an enrichment extraction( c) and( d). Figure 2a shows that during an exhaustion extraction, the first step allows extracting approximately 450 mg / L of“ Active tracer”, compared to only 250 mg / L in the second step. The extraction yield, as shown in Figure 2b, then decreases from 0.35 % in step 1 to 0.07 % in step 2. The discrepancy between the evolution of“ Active tracer” and RS is explained by the significant uncertainty in the measurement of residual solids due to the low concentrations measured, and the difference in solubility between the tracer compound and other constituents of the raw material. The“ Active tracer,” easily extractable in the extraction solvent, is more rapidly“ exhausted” during extraction than other compounds in the raw material. Figure 2c shows that during an enrichment extraction, the concentration of“ Active tracer” increases rapidly between steps 1 and 4( from 564 to 1171 mg / L), reaching a plateau beyond the 6th extraction( 1310 mg / L). Additionally, the yield decreases from 0.44 % in step 1 to 0.07 % in step 4, then remains between 0.03 % and 0.07 % between steps 4 and 6. Thus, from the second step of an exhaustion extraction, the yield is divided by 5. The majority of active principles are extracted during the first step. During an enrichment extraction, there is a change in slope in the curves of“ Active tracer” concentration and RS yield evolution from step 3 or 4. Beyond this inflection point, the extraction yield stabilizes. This stabilization of the extraction yield observed from step 4 onwards is probably due to the progressive saturation of the solution. Conducting a second series of enrichment extractions confirmed this inflection point around steps 3 and 4 and the attainment of a plateau from step 6 to step 9( data not shown).
Figure 1: Diagram of the extraction process known as exhaustion or enrichment
38 Heat Exchanger World July 2025 www. heat-exchanger-world. com