Browsing by Author "Torres Lozada, Patricia"
Now showing 1 - 8 of 8
Results Per Page
Sort Options
Item Análisis de peligros y puntos críticos de control en plantas convencionales de tratamiento de agua(Interciencia Association, 2018-01-16) Pérez Vidal, Andrea; Delgado Cabrera, Luis German; Escobar Rivera, Juan Carlos; Cruz Vélez, Camilo Hernán; Torres Lozada, PatriciaEl sistema de análisis de peligros y puntos críticos de control (APPCC) es una herramienta de amplio uso en la industria de alimentos y recomendada en el enfoque de los planes de seguridad del agua (PSA). En este estudio se adaptó una propuesta metodológica aplicable a los procesos de tratamiento de agua que integró los principios del sistema APPCC y los PSA. El estudio se realizó en una planta convencional de potabilización (PTA) en la ciudad de Cali, Colombia, y comprendió dos etapas: 1) identificación de peligros y eventos peligrosos, y 2) determinación de puntos críticos de control (PCC) y puntos de atención (POA). En la primera etapa se caracterizó el agua cruda, clarificada, filtrada y tratada mediante diez jornadas de muestreo y caracterización, en un periodo de 18 meses. En la segunda etapa se adaptó un árbol de decisión que fue aplicado en los eventos peligrosos categorizados en nivel de riesgo medio o superior. Se identificaron un total de 40 eventos peligrosos, 26 PCC y 10 POA, encontrándose como principales PCC las fases de coagulación, floculación/clarificación, filtración y desinfección. La determinación de los PCC contribuyó a la priorización de las fases del tratamiento que requieren de la ejecución de planes de mejoramiento o soporte definidos en los PSA, resultando prioritarios la captación, canales y tuberías de conducción.Item Biological stability and phytotoxicity of sludge generated from extended aeration activated sludge systems(Elsevier B.V., 2025-02) Cárdenas Talero, José Luis; Millán Castro, María del Mar; Silva Leal, Jorge Antonio; Pérez Vidal, Andrea; Torres Lozada, PatriciaActivated sludge technology is widely used for treating municipal wastewater. In particular, the extended aeration activated sludge (EAAS) method shows longer sludge retention time (SRT), which may enhance the biological stability of the resulting sludge. In this study, the biological stability of secondary sludge without dewatering (SS) and dewatered secondary sludge (DSS), dried in a conventional drying bed for 25 days, were examined using two full-scale EAAS systems operating under varying environmental and operational conditions (EAAS1: 24 °C; 926 masl; SRT 16.8 days and EAAS2: 16 °C; 2513 masl; SRT 23.6 days). The volatile solids to total solids ratio (VS/TS), volatile solids reduction (VSR), and specific oxygen uptake rate (SOUR-20) were assessed as indicators of biological stability. Germination tests (phytotoxicity) using radish seeds were conducted with soil-to-sludge mixtures (0:100, 25:75, 50:50, 75:25) and controls of soil only and distilled water. SRT showed a strong correlation with the biological stability of sludge. The EAAS systems did not ensure biological stability for SS, DSS did achieve biological stability, indicating that the dewatering stage, in addition to reducing moisture, contributes to the biological stabilization of the sludge. Heavy metal concentrations in SS and DSS were within regulatory limits, but pathogen levels exceeded them. Phytotoxicity in the SS and DSS was observed at higher sludge concentrations (0:100, 25:75), but the 50:50 mixture showed no toxicity, and the 75:25 mixture even enhanced germination. The results showed that DSS from EAAS systems have agricultural potential; however, their use is contingent upon additional treatments to eliminate pathogens.Item Development and implementation of a water-safety plan for drinking-water supply system of Cali, Colombia(Elsevier GmbH, 2019-11-25) Pérez Vidal, Andrea; Escobar Rivera, Juan Carlos; Torres Lozada, PatriciaThe water-safety plan (WSP) approach integrates risk assessment and management practices into a drinking-water supply system (DWSS), ensuring water quality from the catchment to the consumer. This research was oriented toward the development and implementation of a WSP in the DWSS for the city of Santiago de Cali, Colombia. We adapted the methodological stages of the WSP established by the World Health Organization: (i.) assemble a WSP team, (ii.) describe the existing DWSS, (iii.) identify hazards and hazardous events, (iv.) evaluate risks, and (v.) plan risk management. In this methodological structure, we propose the use of different risk assessment tools at each step of DWSS, which can be implemented in water systems of different sizes. The results of our study allowed the identification of hazardous events that may compromise the effectiveness of the WSP: Of the 103 events found, 16 were related to the catchment, 40 to treatment processes, 27 to the distribution system, and 9 to consumers, while the remaining 11 were associated with organizational, planning, contingency, and emergency factors. We found that the most critical components of the DWSS are the distribution system and the consumers, with 29.6% and 33.3% of the hazardous events classified as at a very high risk level, respectively. Clearly, improvement and support programs for the WSP were needed to optimize existing control measures and corrective actions and to evaluate new ones to reduce risk levels. The treatment processes and distribution system steps were shown as the main barriers of the DWSS mainly they are under governance of water company, unlike the catchment and consumers which presented higher levels of risk because in these steps the water company has less control and influence. Our research confirms that the WSP is an important tool for decision-making by water-service companies—improving their administrative, financial, organizational, and operational management. It also shows that it is essential that their senior management and other stakeholders be part of the WSP team at each stage of implementation of the DWSS.Item Effect of biosolids on the nitrogen and phosphorus contents of soil used for sugarcane cultivation(2021) Silva Leal, Jorge Antonio; Pérez Vidal, Andrea; Torres Lozada, PatriciaThe application of biosolids improves soil nutrient availability and crop productivity; however, their application needs to be carefully evaluated so as to avoid the risk of contamination. In this study, a 12-month field experiment using a randomized block design with factorial arrangement was conducted to evaluate the effects of biosolids on the nitrogen and phosphorus contents of a sugarcane-cultivated inceptisol. Three types of dewatered biosolids were used: anaerobically digested (B), anaerobically digested and thermally dried (BST), and anaerobically digested and lime-stabilized (BA) biosolids. The results showed that biosolid use increases soil nitrogen content by up to 37% of the total Kjeldahl nitrogen, 42% of NO3−, 13% of NO2−, and 32% of NH4+. Biosolid treatments exceeded the phosphorus requirement for sugarcane cultivation by up to 277% for B, 170% for BST, and 368% for BA. The application of biosolids sufficient to meet crop nitrogen requirements significantly increased soil phosphorus content, suggesting an overdose and low crop response to the available phosphorus. The application of biosolids yielded results similar to those of mineral fertilizers, suggesting their potential use in agriculture.Item Hazard identification in watersheds based on water safety plan approach: Case study of Cali-Colombia(Gheorghe Asachi Technical University of Iasi, Romania, 2016-04) Pérez Vidal, Andrea; Torres Lozada, Patricia; Escobar Rivera, JuanWithin the framework of the Water Safety Plan (WSP), it is necessary to assess and to manage risks in the catchment area, considered the first protection barrier of water supply systems. The Cauca River is one of the major water resources of Colombia and the principal source of drinking water supply for the city of Cali (approx. 2,300,000 people). Taking into account, usually in developing countries, available information and specialized technical resources are limited, in this study were evaluated three management tools of simple application for hazard identification, as a support of risk assessment in the watersheds and integrated with the WSP methodology. The used tools were: (i) matrix of hazardous events, (ii) calculation of Water Quality (WQI) and Water Pollution (WPI) Indexes, and (iii) hazard maps using Geographic Information Systems (GIS). The results showed that the progressive deterioration of water quality is associated with different types of land use of the watershed, which causes diffuse pollution and point source pollution, resulting in the exposure of served population to health risks if adequate treatment barriers are not implemented before the distribution to consumers. The three evaluated tools, showed their usefulness as inputs to risk management and support in activities of surveillance and water quality control. It is important to highlight that the strengthening of the cooperation and active participation of inter-agencies and stakeholders are crucial strategies for risk management in the watersheds.Item Influence of the application of biosolids on the content of humic and fulvic acids in soil cultivated with sugar cane(Fundacion CIPAV, 2016-05-01) Silva Leal, Jorge Antonio; Madriñan Molina, R.; Torres Lozada, PatriciaThis study evaluated the effect of the application of biosolids from a municipal wastewater treatment plant on the content of humic and fulvic acids in vertic Endoaquept soil cultivated with sugar cane. Eight treatments with a randomized block spatial distribution are evaluated using experimental units of 6 m wide x 20 m long: i) control; ii) mineral fertilizer; iii) dehydrated biosolid 1N and 2N; iv) thermally dried biosolid 1N and 2N; and v) alkalized biosolid 1N and 2N (1N and 2N correspond to doses equivalent to one and two times the nitrogen requirement for sugar cane). The results show that while values of humic and fulvic acids showed no significant differences between the control, mineral fertilizer and alkalized biosolid treatments, the application of dehydrated and thermally dried biosolid treatments increased humic acid and fulvic acid content in the soil. This finding demonstrates the benefits of applying such biosolids.Item Physicochemical, microbiological characterization and phytotoxicity of digestates produced on single-stage and two-stage anaerobic digestion of food waste(2021) Parra Orobio, Brayan Alexis; Rotavisky Sinisterra, María Paula; Pérez Vidal, Andrea; Marmolejo Rebellón, Luis Fernando; Torres Lozada, PatriciaOrganic amendments favor the development of sustainable agriculture by using less chemical fertilizers. In this way, the use of digestates from anaerobic digestion as soil conditioners in agriculture has been gaining interest due to their important N and P nutrient contents, among others. This study evaluated the potential use of digestates from anaerobic reactors treating food waste in single (D1) and two-stages (D2: hydrolytic/acidogenic and D3: acetogenic/methanogenic) configurations. Digestate characteristics and their potential application conditions (100, 50, 25, and 5%) were evaluated using Raphanus sativus as an indicator species. D3 reported the best performance in terms of: (i) better physicochemical, microbiological, and parasitological characteristics, being a class B material, without exceeding the established limits for heavy metals, fecal coliforms (FC < 1000 CFU 100 mL− 1), Salmonella spp. (0 CFU g− 1), and viable helminth eggs (0 HE g− 1); (ii) better stability indicators on D3, followed by D1 (volatile solids/total solids (VS/TS): 0.57 and 0.65, pH: 8.63 and 6.80, respectively), while D2 was the most unstable digestate (VS/TS > 0.87 and acidic pH); and (iii) greater potential for agricultural use, since a 5% dose produced a germination index > 120%, whose effect is associated with the presence of humic and fulvic acids and with N and P concentrations > 1%. In addition, the study reported that volatile fatty acids > 2500 mg L− 1 act as antimicrobial agents, reducing the required pathogen removal pretreatments.Item Potential production of struvite from the anaerobic digestion of food waste: Analysis in one-phase and two-phase configurations(2021) Parra Orobio, Brayan Alexis; Pérez Vidal, Andrea; Torres Lozada, PatriciaAnaerobic digestion (AD) of food waste (FW) has been gaining more interest as it has potential for the production of organic amendments with high struvite content, which is a nutrient of great interest in sustainable agriculture. The effect of AD of FW in one- and two-phase configurations on CH4 production and the potential for struvite formation using digestate was investigated. The two-phase was more efficient as its organic loading rate is 18% higher than that of one-phase configuration. Also, the two-phase yielded a higher CH4 content in biogas (>60%) and a higher organic matter transformation in each of the AD stages (>20%). The digestate complied with the regulatory requirements for the use of organic amendments, thereby being deemed as a Type-B material with a struvite precipitation potential, exceeding 80%, as opposed to the digestate from one-phase configuration, which may represent a revenue of up to US$ 26,505/yr.