**2.3 Measurement of particle size (DLS)**

For the measurement of the particle size, the Anton equipment for lite sizer 500 was used, which uses the dynamic light scattering technique (DLS), which indicates the mean value of the intensity distribution called the "Z average" and the polydispersity index with which the width of the distribution is described.

#### **2.4 Jar-test in fish packing wastewater**

The jar technique was carried out in order to determine biopolyelectrolyte dosages among other parameters. In it, the coagulation-flocculation processes were simulated at the laboratory level. Its versatility lies in using a series of jars at the same time with variations in stirring speed (rpm). Chemical and hydraulic factors influence this process. Among these we have:


The pH plays a very important role in the study of the coagulation-flocculation phenomena. This is how a part of the charge of the colloidal particles that have absorbed OH- ions remains destabilized in the colloidal suspension.

*Physicochemical Insights of the Organic Matter Particles Dispersed in Wastewaters Induced… DOI: http://dx.doi.org/10.5772/intechopen.99026*

Since the jar test is only a process simulation, it is necessary to maintain operating conditions such as rapid mixing, which aims to create turbulence or movement necessary to create the necessary contact between the bio-polyelectrolyte and the colloidal particles of the water, in order to neutralize their charges, destabilize them and make them agglomerate in a short period of time. The rapid mixing time is directly dependent on the nature of the coagulant. For example, polymers distribute more slowly than metal ions due to their chain length, therefore they will require a longer time or a greater speed gradient.

800 mL of residual water was taken, then additions of 20, 40, 80, and 100 mL of a chitosan solution were made at 1,000 ppm and the time and rpm that were used are 5–10 min, 30–100 rpm [8].

Generally, the slow mixing time does not exceed 15 minutes. Since an excessive time can create heating of the sample causing more efficient flocculation, but at the same time poor sedimentation, the release of gases dissolved in water occurs, forming bubbles that adhere to the flocs and make them float [9]. In this process, it is recommended 3–15 min., 20–40 rpm, finally, a rest of 30 min., which will allow the formed flocs to settle.
