Mateus Pimentel de Matos

Biological and physicochemical methods are commonly used to remove phosphorus (P) from wastewater; however, these can present limitations. Therefore, this study aimed to evaluate the effectiveness of water treatment plant sludge from the Federal University of Lavras campus and natural zeolite. The chemical composition and pH were analyzed. Two experimental adsorption assays were conducted in phosphate solutions at concentrations of 25, 50, 75, and 100 mg.L-1 P-PO43-, designated as P25, P50, P75, and P100, respectively. In the first test, sludge and zeolite were used in both powdered and granular forms. The second test evaluated combinations of adsorbents: S10Z40, S20Z30, S25Z25, S30Z20, and S40Z10. All experiments were performed in triplicate using 0.5 g of adsorbent in 50 mL of P-PO43-solution, agitated at 70 rpm for four hours in a Wagner agitator. The sludge and zeolite samples consisted mainly of iron (Fe), silicon dioxide (SiO2), and aluminum oxide (Al2O3), and the pH of both ranged from 7.5 to 8.0. The granular sludge adsorbent achieved approximately 97% removal at phosphate concentrations (P75 and P100) in the first assay, while zeolite efficiency was consistent across forms, reaching 96% for P75.The second assay showed reduced efficiency, with approximately 20% removal for P25 (p < 0.05) in both S30Z20 and S40Z10 conditions and 14% for P50. For P75 and P100, combined removal did not exceed 10%. These findings highlighted the individual adsorptive capacities of sludge and zeolite under different particle size conditions when applied independently.

The golden mussel (Limnoperna fortunei) poses environmental and infrastructural challenges due to its ability to attach to various substrates and form dense colonies. These colonies are difficult to remove and threaten hydroelectric power stations, water treatment plants and fishing activities. However, the high calcium carbonate content of golden mussel shells (GMSs) presents an opportunity for phosphorus (P) recovery from wastewater, addressing both waste management and resource scarcity. This study evaluated the effectiveness of GS for P recovery from synthetic and real wastewater. Batch experiments were conducted to assess P recovery capacity under varying adsorbent dosages, pH levels, contact times and isotherm conditions (Langmuir, Freundlich and Temkin). Also, the chemical and physical analyses of GMSs were performed to elucidate the mechanisms of P recovery. The Freundlich isotherm model best describes the process, while the Langmuir model suggests a maximum recovery potential of approximately 59.9 mg P g⁻¹ of GMS, demonstrating a P recovery efficiency of up to 60.7% at a P concentration of 40–50 g L⁻¹ and a contact time of 3 h. Due to the predominance of negative charges, it was concluded that the precipitation was the major mechanism for P recovery by GS. This study highlights the potential of GMSs as a sustainable and low-cost material for phosphorus recovery in wastewater treatment, offering a promising solution for both waste valorization and environmental management contributing to a circular economy.

The aim of this study was to evaluate the anaerobic degradation of dairy wastewater with and without the application of lactase. Two UASB reactors (16 L) were built to treat synthetic dairy wastewater (DWW). Four organic loads (0.5, 1.0, 2.0, and 3.0 kg m^–3 d^–1 COD) were applied for 45, 95, and 45 days, keeping the HRT at 1 day. Ammonium sulfate and potassium phosphate were added to the DWW (COD:N:P of 500:5:1) and sodium bicarbonate (pH equal to 7.0). UASB1, which received DWW with lactase, showed no difference in COD removal efficiency compared to UASB2, which received DWW without lactase. The average COD removal efficiencies were 69, 77, 70, and 56% for UASB1 and 68%, 72%, 69%, and 57% for UASB2 in each phase. From the Monod kinetics, Y is the growth coefficient (mg mg^–1 d^–1); K_d is the endogenous decay coefficient (d^–1); μ_max is the maximum microbial growth rate (d^–1); and K_S is the limiting substrate concentration (mg L^–1) equal to 1.16 and 1.20; 0.05 and 0.04; 0.18 and 0.13; and 248 and 109, respectively, for UASB1 and UASB2. It can be concluded that the analysis of the anaerobic degradation of DWW in the UASB reactor proved to be adequate, with COD removal efficiencies considered satisfactory (70–76%). The application of lactase as a pre-treatment was not effective in increasing the biodegradability of synthetic dairy wastewater.

This study proposes the was to evaluate the stability and methane production with organic load differents in an upflow anaerobic sludge blanket reactor (UASB) treating swine wastewater by methods of multivariate analysis. Four organic loads were used with average hydraulic holding times of one day. The methods of data analysis of linear regression, Pearson correlation, principal component analysis and hierarchical clustering analysis were used for understanding stability and methane production in the reactor. The highest concentrations of bicarbonate alkalinity of 683 mg L⁻¹ CaCO₃ and total volatile acids of 1418 mg L⁻¹ HAc with maximum organic loading applied were obtained. The optimal stability conditions occurred at an intermediate and partial alkalinity ratio between 0.24 and 0.25 observed in initial phases with a chemical oxygen demand (COD) removal of 47–57%. Maximum methane production was 9.0 L CH₄ d⁻¹ observed with linear regression positive and occurred at the highest applied organic load, corresponding to the highest COD removal efficiency and increased microbial biomass. Positive and negative correlation between functional stability in anaerobic digestion showed regular activity between acids, alkalinity and organic matter removal. This fact was also proven by the analysis of principal components that showed three components responsible for explaining 83.2% of the data variability, and the alkalinity, organic matter influent and organic acids had the greatest effects on the stability of the UASB reactor. Hierarchical clusters detected the formation of five groupings with a similarity of 50.1%, indicating that temperature and pH were variables with unitary influences on data dimensionality.

Conventional wastewater treatment plants (WWTPs) present low phosphorus (P) removal capacity. Conversely, water treatment plants (WTPs) produce sludge with great P sorption from wastewater; however, directly adding the sludge into the wastewater treatment system could increase the effluent turbidity. As a novel approach, the present study evaluated the performance of WTP sludge within paper sachets for P removal from treated sewage. Different sludge concentrations (2–30 g L−1) and contact times (1–27 d) were applied to treat sewage from a university WWTP outlet. The sludge was characterized by P, Fe, and Al content. Larger sludge masses showed higher P removal efficiencies due to their high Fe content, especially at longer contact times (up to 100% at the final of the experiment). However, there is a more significant P reduction in the first 10 d (more than 90% in the most efficient treatment – 30 mg L−1). Based on the kinetic and isotherm analyses and the sludge chemical composition, precipitation proved to be a mechanism of great importance in P removal. Therefore, WTP sludge sachets can be a promising way to remove P from sewage, and the formed solid waste might be reused as an alternative fertilizer.

Coffee production plays an essential role in the Brazilian economy, and a large production centre is located in Minas Gerais. In recent years, there has been an increase in coffee cultivation, consequently generating coffee wastewater (CW) and solid waste (skin, pulp, parchment, and dregs) during the processing stage. Thus, the present review study seeks to characterize these by-products from the coffee production chain and present their possible applications in agribusiness and other sectors towards a circular economy, mainly related to reuse as fertilizer or energy and biomaterial recovery. CW treatment is complex given the high concentrations of organic matter, phenols, and nutrients, especially potassium. Still, its use as a liquid fertilizer is highly recommended as it can increase crop yield. In this regard, CW should be applied to soil according to nutritional criteria, with potassium as the reference chemical element. The wastewater production and its potential for soil contamination can be reduced by applying biological, physical, or chemical treatment along with recirculation routes during the washing/peeling/pulping of coffee berries. Moreover, the solid waste from coffee production can be used for energy generation, wastewater treatment (as an organic filter material or biochar), and as organic fertilizer (in natura or composted). Key words: Coffee wastewater; fertigation; nutrients; recirculation; agro-industrial solid waste.

RESUMO A epidemiologia baseada em esgotos é uma importante ferramenta de saúde pública com grande aplicabilidade no enfrentamento à pandemia de COVID-19, visto que indivíduos infectados são capazes de excretar partículas de SARS-CoV-2. Diante desse contexto, este estudo objetivou correlacionar o número de casos de COVID-19 com variáveis físicas e químicas e presença do vírus em amostras de esgoto bruto provenientes de uma estação de tratamento de esgoto (ETE) do município de Lavras (MG) coletadas entre as 19ª e 25ª semanas epidemiológicas. As amostras foram concentradas pelo método de adsorção em membrana eletronegativa, e o RNA de SARS-CoV-2 foi extraído, detectado e quantificado por reação da transcriptase reversa seguida pela reação em cadeia da polimerase (RT-qPCR) utilizando-se oligonucleotídeos e sondas para o gene N. Ademais, as variáveis pH, sólidos suspensos totais e demanda química de oxigênio foram avaliadas. Os casos de COVID-19 foram obtidos de boletins epidemiológicos disponibilizados pela prefeitura. Na 24ª semana epidemiológica, observou-se redução na concentração viral (cópias L-1) concomitantemente às medidas de enfrentamento à pandemia iniciadas pelo município. Correlação positiva forte e significativa (p < 0,05) entre carga viral e número de casos confirmados foi obtida por meio do teste de Spearman, entretanto não houve correlação entre a presença do vírus e as características físicas e químicas do esgoto. Sugere-se, portanto, que novas pesquisas sejam realizadas com a finalidade de rastrear a concentração de SARS-CoV-2 em águas residuárias, corroborando, desse modo, com o enfrentamento à pandemia e a obtenção de sistemas de vigilância epidemiológica por meio do monitoramento de esgotos.