58 SEPTEMBER • WORLD AQUACULTURE • WWW.WAS.ORG reduction of organic matter and by changes in turbidity and dissolved oxygen throughout the system, from the point of entry to the point of exit. The decrease in turbidity is an indirect indicator of the reduction of suspended solids and organic particles, while the DO largely reflects the microbial activity within the system for the reduction of organic matter, allowing the quality and efficiency of the system in operation to be estimated. The results far exceeded initial expectations and confirmed the system’s potential to optimize wastewater management under real operating conditions. At Molco, BOD levels were reduced by 87%, while at Río Cude the reduction reached 97%, with an overall average of 92%. In terms of Total Suspended Solids (TSS), Molco achieved an 85% reduction and Río Cude 98%, averaging 91.5%. Analyses also showed an average 79.5% reduction in Total Kjeldahl Nitrogen and a 90.5% reduction in phosphorus. These results not only meet but surpass the regulatory Chilean industrial wastewater standards set by normative DS90, demonstrating IP™’s efficiency and reliability under demanding operational conditions. The most notable changes were evident in the turbidity parameter, showing at the affluent a turbidity of 272.70 ± 297.58 NTU in the AM measurements, and 370.10 ± 326.58 in the PM measurements, and at the effluent a turbidity of 8.37 ± 4.69 in the AM, and 11.30 ± 6.69 in the PM (Figure 8). To achieve NTU reduction, several biological processes are involved which directly affect the oxidation and degradation of organic matter. It is necessary to highlight that sedimentation is an important process in the reduction or decrease of turbidity or suspended solids in most conventional technologies (Guerrero et al. 2018). In the IPTM technology this option is ruled out due to the dynamics of the system and throughout the trials there was no evidence of sediment accumulation (Merino 2025). The oxidation-reduction potential (ORP) reflects the ability of the IPTM system to maintain an oxidizing or reducing environment. An oxidizing environment favors the aerobic decomposition of organic matter, while a reducing environment indicates the lack of free oxygen and the possible appearance of anaerobic processes. From the results obtained, it was shown that ORP values tend to be lower in the morning and higher during the afternoon (Table 1). This diurnal pattern reflects the system’s ability to maintain an oxidizing environment in the early hours of the morning and throughout the day favor reducing activity. However, the ORP decrease during the morning can also be an indication of greater oxygen consumption due to biological activity. These ORP results indicate that in general the IPTM system works under oxidizing conditions, which is favorable for the degradation of organic matter. TABLE 1. Variation of ORP at sampling Points during the morning and afternoon at Molco (Merino, 2025) Parameter Time Point 1 Point 2 Point 3 Point 4 Point 5 ORP (mV) am 64.25 ± 105.54 64.28 ± 81.93 62.76 ± 80.58 65.98 ± 73.05 60.85 ± 64.18 pm 88.26 ± 85.87 73.22 ± 80.13 69.96 ± 79.09 70.49 ± 73.74 66.30 ± 66.47 TABLE 2. Water quality parameters measured at three sampling points in IPTTM System (Merino, 2025). Sampling Alkalinity DBO5 Nitrite Nitrate TKN pH TDS point mg/L CaCO3 mg/L mg/L mg/L mg/L mg/L 1 300 687 0.14 4.3 68 7.55 4120 3 342 393 0.14 3 64.7 7.88 210 5 295 103 0.17 6 44.9 7.81 170 TABLE 3. Temperature variation in IPTM System at sampling points during the morning and afternoon (Merino, 2025) Parameter Time Point 1 Point 2 Point 3 Point 4 Point 5 Temperature °C am 10.61 ± 1.59 10.55 ± 1.74 10.33 ± 1.71 10.38 ± 1.76 10.56 ± 2.05 pm 11.17 ± 1.41 10.95 ± 1.51 10.75 ± 1.44 10.67 ± 1.48 10.61 ± 1.39 FIGURE 7. IPTM pilot plant deployed at Rio Cude salmon land-based semi recirculating facility (J. Barraza)
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