Optimization of indirect wastewater characterization using led spectrophotometry: a comparative analysis of regression, scaling, and dimensionality reduction methods.

LED spectrophotometry is a robust technique for the indirect characterization of wastewater pollutant load through correlation modeling. To tackle this issue, a dataset with 1300 samples was collected, from both raw and treated wastewater from 45 wastewater treatment plants in Spain and Chile collected over 4 years. The type of regressor, scaling, and dimensionality reduction technique and nature of the data play crucial roles in the performance of the processing pipeline.

Towards highly economical and accurate wastewater sensors by reduced parts of the LED-visible spectrum.

Interest is growing in simple, fast and inexpensive systems to analyze urban wastewater quality in real time. In this research project, a methodology is presented for the characterization of COD, BOD, TSS, TN, and TP of wastewater samples, without the need to alter the samples or use chemical reagents, from a few wavelengths, belonging to the different color groups that compose the visible spectrum in isolation: (380-700 nm): violet (380-427 nm), blue (427-476 nm), cyan (476-497 nm), green (497-570 nm), yellow (570-581 nm), orange (581-618 nm), and red (618-700 nm). In this study, about 650 raw and treated urban wastewater samples from over 43 WWTPs and a total of 36 estimation models based on genetic algorithms have been calculated.

Evaluation of genetic models for COD and TSS estimation in wastewater through its spectrophotometric response.

In an urban wastewater treatment plant (WWTP), early knowledge of the pollutant load levels throughout the plant is key to optimize its processes and achieve better purification levels. Molecular spectrophotometry has begun to gain prominence in this wastewater characterization process, as it is a simple, fast, inexpensive and non-invasive technique. In this research work, different mathematical models based on genetic algorithms have been developed for the estimation of chemical oxygen demand (COD) and total suspended solids (TSS) from the spectral response of the samples, measured in the 380-700 nm range by means of a light-emitting diode (LED) spectrophotometer developed by the researchers.

Implementing Early Warning Systems in WWTP. An investigation with cost-effective LED-VIS spectroscopy-based genetic algorithms.

Measuring how the pollution load evolves in real time along sewer networks is key for proper management of water resources and protecting the environment. The technique of molecular spectroscopy for water characterization has increasingly widespread use, as it is a non-invasive technique that leads to the correlation of the physical-chemical conditions of wastewater with spectroscopic surrogates by a series of mathematical estimation models. In the present research work, different symbolic regression models obtained with evolutive genetic algorithms are evaluated for the estimation of chemical oxygen demand (COD); five-day biochemical oxygen demand (BOD); total suspended solids (TSS); total phosphorus (TP); and total nitrogen (TN), from the spectral response of samples measured between 380 and 700 nm and without the use of chemicals or pre-treatment.

Wastewater Quality Estimation Through Spectrophotometry-Based Statistical Models.

Local administrations are increasingly demanding real-time continuous monitoring of pollution in the sanitation system to improve and optimize its operation, to comply with EU environmental policies and to reach European Green Deal targets. The present work shows a full-scale Wastewater Treatment Plant field-sampling campaign to estimate COD, BOD, TSS, P, TN and NON in both influent and effluent, in the absence of pre-treatment or chemicals addition to the samples, resulting in a reduction of the duration and cost of analysis. Different regression models were developed to estimate the pollution load of sewage systems from the spectral response of wastewater samples measured at 380-700 nm through multivariate linear regressions and machine learning genetic algorithms.

Performing Calibration of Transmittance by Single RGB-LED within the Visible Spectrum.

Spectrophotometry has proven to be an effective non-invasive technique for the characterization of the pollution load of sewer systems, enabling compliance with new environmental protection regulations. This type of equipment has costs and an energy consumption which make it difficult to place it inside a sewer network for real-time and massive monitoring. These shortcomings are mainly due to the use of incandescent lamps to generate the working spectrum as they often require the use of optical elements, such as diffraction gratings, to work.

Spectroscopy Transmittance by LED Calibration.

Local administrations demand real-time and continuous pollution monitoring in sewer networks. Spectroscopy is a non-destructive technique that can be used to continuously monitor quality in sewers. Covering a wide range of wavelengths can be useful for improving pollution characterization in wastewater.

[Biochemical recurrence in patients with prostate cancer after radical treatment. Comparative study of prostatectomy vs. radiotherapy].

Objectives: To compare the biochemical relapse-free survival between radical prostatectomy and radiotherapy in patients with localized prostate cancer of low and intermediate recurrence risk.

Methods: A retrospective study of 435 patients with localized prostate cancer, radical prostatectomy was performed in 65% of patients and radiotherapy was in 35%. The Kaplan-Meier Estimator was used to assess the biochemical relapse-free survival and long-rank test, Breslow and Tarone-Ware to evaluate the differences between the groups with confidence intervals at 95%.