Operational evaluation of the wastewater treatment system in Esteli, Nicaragua

Abstract

The present work was carried out with the objective of evaluating the efficiency, operation and maintenance of the Wastewater Treatment System of the city of Estelí, through the determination of the physicochemical and bacteriological parameters established in the Artos. 22 and 23 of Decree 33-95 and the standard NTON 05 027 05. The treatment system is composed of 3 independent modules, each module consisting of 3 treatment units (UASB + facultative lagoon + maturation). For the determination of the flow variations at the entrance and exit of the STAR, measurements were made for three consecutive days with a frequency of 8h, using rectangular channels and parshall channels to know the flow of tributary and effluent. Sampling was carried out during 3 consecutive days of sampling the following parameters were analyzed: water temperature, total suspended solids, sedimentable solids, BOD5, COD, fats and oils, methylene blue and fecal coliforms, which through laboratory analysis provided. The necessary information on the operation of the system. The composite samples were made at the general entrance and exit of the STAR where six samplings were carried out for three consecutive days, with frequency of 10h. The simple samples were run for one day with a frequency of 1h, at the entrance and exit of the UASB reactors and stabilization ponds comprising each module. The total efficiency of the system according to the removal of BOD5, COD and fecal coliforms was 92.48%, 86.95% and 81.16% respectively, however the percentage of coliform removal is not enough to comply with Art 22 and 23 of Decree 33 -95.