Most of the water supplied in Brazil comes from water streams that may have higher values for apparent color than turbidity. Treatability trials were performed for color and turbidity removal to evaluate the advantages of coagulation during the charge neutralization mechanism when compared to sweep flocculation for water with those characteristics. There were three types of trials: conventional Jar Test with raw water, with and without filtration, and in a pilot Water Treatment Plant, direct downward filtration, with synthetic water. Auxiliary equipment such as Continuous Flocculation Monitoring Equipment (CFME) and image analysis were used to evaluate the growth of flocs. In the Jar Tests experiments, similar levels of color (61.49%) and turbidity (61.30%) removal were observed, with a lower dosage of coagulant (46 mg/L) in the charge neutralization mechanism compared to the ones with sweep flocculation (58.22% for color and 54.73% for turbidity removal with 52 mg/L of aluminium sulfate). Similar results were found on pilot plant. At filtration rates of 180 and 300 m³ m⁻² day⁻¹, sweep flocculation mechanism had shorter filtration cycle (<5 m³) compared to other mechanisms. Therefore, a change in the operation of Water Treatment plants that use a coagulant dosage associated with sweep flocculation can bring advantages such as the reduction of coagulant consumption and sludge productions, as well as the increase of chlorine disinfection and filtration cycles.

Water distribution networks are the most important and costly infrastructure assets of the water supply system, responsible for ensuring a steady and reliable water supply to the end user. Consequently, they are fundamental to the socioeconomic prosperity and health of the population. Therefore, determining pipeline renewal strategies is essential in system management. In this article, the development and application of a simplified risk assessment model allowed to highlight the pipes most susceptible to failures and their respective qualitative (water quality index) and financial consequences in a real case study. The results classified approximately 30 km of the distribution network, highlighting 11 pipes with a high risk of failure (≈3.7 km) and an estimated replacement value of BRL 3.2 million, as a priority for renewal in the next 2 years. In small- and medium-sized water distribution systems with limited technical and financial resources, this model can prove highly useful, as it uses free computer tools and a simple methodology that does not depend on statistical models, mathematical estimates, complex regressions, and intensive computational resources.

RESUMO Neste artigo, empregou-se um equipamento de monitoramento contínuo da floculação (EMCF) para melhor compreensão da coagulação e da floculação no tratamento de águas sintéticas sob diferentes mecanismos de coagulação, em escala de bancada. A água de estudo utilizada nos ensaios foi preparada em laboratório com a adição de uma solução de caulinita em água. Como agente coagulante foi utilizado sulfato de alumínio (SA) líquido, isento de ferro. A resposta do sinal com o tempo mostra três regiões distintas: uma região de crescimento, uma região de patamar e uma região de decaimento. Ao longo do presente trabalho, constatou-se que o índice de floculação (IF) se mostrou adequado para otimizar a floculação tanto pela seleção do pH quanto pela dosagem do coagulante. O pH e as dosagens ótimas, obtidos por meio do ensaio de jarros, estiveram relacionados às maiores variações de IF. O IF médio ( IF ) mostrou-se adequado para antecipar a dosagem ótima a partir de 3 minutos de floculação, e a inclinação da reta de melhor ajuste mostrou-se adequada para estimar a cinética da floculação.

This article aimed to study the influence of the velocity gradient on the flocculation process by aluminum sulfate (AS) in raw water samples under the action of a sweep mechanism at a temperature of 20°C and, with the help of continuous flocculation monitoring equipment (CFME), to verify the potential use of the flocculation index (FI) as a way to choose an adequate velocity gradient to achieve higher sedimentation rates and to obtain kinetic flocculation aggregation (K_A) and breakup constant (K_B) data. K_A and K_B helped to explain why the best tapered velocity gradient (G) conditions (G_{0 − 5 min} = 80 s^− 1, G_{5 − 10 min} = 50 s^− 1 and G_{10 − 15} min = 20 s^− 1: 83.4%) promoted greater turbidity removal efficiency than did the fixed gradient (G_{0 − 15 min} = 20 s^− 1: 78.6%), highlighting the compartmentalization benefits. It was also observed that floc size was the most relevant factor for selecting velocity gradients that generated greater removal efficiencies for turbidity and apparent color. Finally, the model developed through kinetic constants was applied to water treatment plant conditions, and the mean absolute errors were 1.5% and 0.1 s^− 1, considering the turbidity removal efficiencies and the best estimated velocity gradients, respectively, allowing us to improve the quality of the treated waters.

This study analyzed interventions in a drinking water supply system from 2016 to 2021 over a six-year period using statistical tools and a Geographic Information System (GIS) for detailed mapping. This research highlighted correlations between turbidity, apparent color, and iron content, which significantly influenced water quality. Key interventions included increasing the chlorine dosage and replacing old metal pipes with new plastic ones, resulting in an overall 6% improvement in water quality. Although the Modified Water Quality Index by the Canadian Council of Ministers of the Environment identified certain districts with critical water quality levels, only spatial analysis could pinpoint specific pipes and areas within these districts that showed improvements, thereby guiding future investment strategies.