**2.5 Experimental test for wastewater treatment**

To estimate the dye biodegradation, we selected the EBt dye as a model. The EBt solutions were prepared at pH 5.48 and three different concentrations, namely, 5 mg/L, 10 mg/L and 20 mg/L. Biodegradation tests were conducted by introducing 5 mg of the bionanocompound and 5 mL of dye solution into each micromixer for 25 minutes at a constant rate of 12 mL/h. A neodymium permanent magnet, of

#### **Figure 1.**

*Micromixers geometries. A) One loop, B) two horizontal loops, C) two vertical loops, D) circular, E) triangular and F) rectangular-3D.*

**97**

**Table 1.**

*Micromixers for Wastewater Treatment and Their Life Cycle Assessment (LCA)*

349.23 mT, was externally inserted into the loops of some of the devices to retain the bionanocompounds while the reaction occurred. For devices that lack loops for permanent magnets, separation of the bionanocompounds by placing the magnets at the outlets of the system (See **Figure 2**). All experiments were carried out in triplicate. After the treatment, each sample was collected and analyzed spectrophotometrically in a GENESYS 10S UV–Vis v4.004 2L5R078128 (Thermo SCIENTIFIC, USA) An absorbance peak was monitored at 545 nm and also the absorbance area of the entire visible spectrum in the range between 400 and 700 nm was calculated.

This life cycle analysis aimed to evaluate possible impacts associated with manufacture and operation of six different micromixers for wastewater treatment. This LCA was based on an attributional approach or descriptive "cradle to gate"

**Stage Inventory Amount Unit** *Single layer micromixer*

*Two layers micromixer*

*Multiple layers micromixer*

*Enzyme activity assay*

*Operation* Water consumption 15 ml *Dye preparation*

*Operation*

*Inventory report of micromixers manufacturing and operation.*

*Manufacturing* Ethanol 2 ml

Polymethyl methacrylate (PMMA) 0.011 m3

Polymethyl methacrylate (PMMA) 0.017 m3

Polymethyl methacrylate (PMMA) 0.034 m3

Ethanol 1 ml Energy 0.339 kWh Water consumption 53 ml

Energy 0.577 kWh Water consumption 51 ml

Ethanol 5 ml Energy 1.293 kWh Water consumption 51 ml

Citric acid 0.060 g

ABTS 0.110 g Energy 0.057 kWh

Eriochrome black 0.0001 g Water consumption 5 ml

Energy 0.020 kWh

Disodium hydrogen phosphate 0.050 g

*DOI: http://dx.doi.org/10.5772/intechopen.96822*

All measurements were carried out in triplicate.

**2.6 LCA requirements**

*2.6.1 Goal and scope*

#### **Figure 2.**

*Experimental scheme performed for on the micromixers by topologies with loops (a) and without (B).*

*Micromixers for Wastewater Treatment and Their Life Cycle Assessment (LCA) DOI: http://dx.doi.org/10.5772/intechopen.96822*

349.23 mT, was externally inserted into the loops of some of the devices to retain the bionanocompounds while the reaction occurred. For devices that lack loops for permanent magnets, separation of the bionanocompounds by placing the magnets at the outlets of the system (See **Figure 2**). All experiments were carried out in triplicate. After the treatment, each sample was collected and analyzed spectrophotometrically in a GENESYS 10S UV–Vis v4.004 2L5R078128 (Thermo SCIENTIFIC, USA) An absorbance peak was monitored at 545 nm and also the absorbance area of the entire visible spectrum in the range between 400 and 700 nm was calculated. All measurements were carried out in triplicate.
