In recent decades, contaminants of emerging concern (CECs) in aquatic environments have garnered significant attention due to their adverse effects on ecosystems and human health. Among these CECs, bisphenol A (BPA) is a major concern because of its widespread use and endocrine-disrupting properties. Brazil's urbanization and industrial growth have led to significant pollution challenges, primarily due to inadequate sewage infrastructure and untreated domestic wastewater being discharged into rivers, contributing to the presence of emerging contaminants in surface waters. This study assessed BPA contamination and estrogenic activity in the Paraíba do Sul River in São Paulo State, Brazil. BPA was detected in 50% of the samples, with concentrations ranging from 11.1 to 116.9 ng L−1. The estrogenic activity assay also showed positive results in 50% of the samples, ranging from 0.12 to 1.36 ng L−1 of estradiol-equivalent, indicating the presence of multiple compounds contributing to estrogenic effects. This underscores the need for a comprehensive approach to monitoring water quality. The water quality index (WQI) revealed compromised water quality at the studied sites, particularly during the rainy season. The correlation between the WQI, BPA, and estrogenic activity parameters suggests that endocrine-disrupting compounds significantly impact water quality, exacerbated by inadequate wastewater treatment infrastructure.

M. ole·ifera se·ed hu·sks (H-M·O) w·ere u·sed as adsorbent for the removal of methylene blue (MB) dye from an aqueous solution. The ads·orbent was char·acterized by SE·M, ED·X, X·RD, F·TIR, B·ET, and p·HPZC. To evaluate adsorption capacity, the influences of p·H, kinetics, isotherms, and thermodynamic prop·erties were anal·yzed. Characteri·zation tech·niques indic·ated that H-MO has het·erogeneous morp·hological charac·teristics wi·th a spe·cific sur·face a·rea of 3.24 m2 g-1, mai·nly comp·osed of ce·llulose distr·ibuted in an amor·phous stru·cture. MB adsorption was favorable at pH values higher than pHPZC of 6.6, using an adsorbent dosage of 1.0 g L-1. Equilibrium was achieved in the first 240 min, and the pseudo-second-order model was suitable for describing the kinetic data. Freu·ndlich was the mo·st adeq·uate model for descri·bing the isoth·erm cur·ves, pred·icting a max·imum adsor·ption capa·city of 122.7 mg g-1 at 24°C, hig·her tha·n oth·er natu·ral ad·sorbents. The ads·orption proc·ess w·as spo·ntaneous and exoth·ermic, indic·ating that lo·wer temper·atures fav·or the ad·sorption and th·at it is cont·rolled by p·hysical fo·rces. The da·ta presen·ted indic·ate the M·B has t·he pot·ential to be succ·essfully trea·ted by the eco-fr·iendly and l·ow-cost ads·orbent M. oleif·era seed h·usks. Keywords: agricultural wastes, low-cost adsorbent, physisorption.

Low-cost and easily accessible sludge treatment technologies are necessary in low- and middle-income countries. This study aimed to evaluate the use of Moringa oleifera seed powder (MO) as a natural sludge conditioner for supernatant quality improvement prior to thickening as a result of gravity settling. The zone settling rate (ZSR) and sludge volume index (SVI) were used to evaluate the gravity settling capacity. Supernatant clarification was evaluated in terms of the capacity to remove turbidity, apparent colour, Escherichia coli, and organic matter associated with zeta potential evolution. The effects on the values of pH and electrical conductivity were also evaluated. Finally, the effects on the toxicity (chronic and acute) of the supernatant effluent were examined. A significant supernatant quality improvement was observed with the addition of MO. The ZSR (0.16 cm/min) and SVI (53 mL/g) results showed that the sludge had good sedimentability, and the addition of MO maintained these characteristics in a statistical manner. Increasing the MO dosage increased the zeta potential of the supernatant, resulting in an optimal dosage of 1.2 g/L, with a removal of 90% turbidity, 70% apparent colour, 99% E. coli, and 40% organic matter. The pH and electrical conductivity values did not change with increasing MO dosage, which is a competitive advantage of MO addition compared to iron and aluminium salt addition. A reduction in the ability to remove organic matter was observed at higher dosages of the natural coagulant due to the presence of residual MO in the final effluent. The optimal MO dosage of 1.2 g/L did not affect the acute or chronic toxicity of the supernatant. These results emphasized that M. oleifera seed powder can improve the supernatant quality and can potentially be a low-cost and easily accessible conditioner for wastewater sludge thickening.

The substance 2,2-bis(4-hydroxyphenyl) propane, commonly known as bisphenol A (BPA), is frequently used to produce epoxy resins and polycarbonate plastics. BPA is also used in the industrial manufacturing of plastic bottles, can linings, and thermal papers¹. Many studies have highlighted the harmful effects of BPA, including its impact on reproduction, genetics, the nervous system, embryo development, and hormonal balance²,³. The permissible BPA concentration differs depending on the water source. Regulating BPA levels within the 1–15 µg L^-1 range in freshwater, seawater, and wastewater is essential to protecting aquatic ecosystems⁴. Studies have shown worldwide BPA contamination in freshwaters used as sources of drinking water after treatment, especially in the most industrialized and urbanized regions⁵-⁹. Considering that the conventional drinking water treatment process, which involves coagulation, flocculation, sedimentation, and filtration stages, has low BPA removal rates¹⁰,¹¹ and is the most applied process worldwide¹², developing alternative treatments for BPA removal from water is imperative.

A presença de contaminantes emergentes em ambientes aquáticos tem se tornado uma preocupação crescente devido aos seus impactos potenciais sobre os ecossistemas e a saúde humana. O bisfenol A (BPA) é amplamente utilizado na indústria, apesar de ser um desregulador endócrino, e frequentemente detectado em corpos hídricos devido ao descarte inadequado de efluentes industriais e domésticos. Este estudo investigou a contaminação por BPA e a atividade estrogênica em seis pontos de amostragem ao longo do trecho paulista do Rio Paraíba do Sul, Brasil, nos municípios de Santa Branca, Jacareí, São José dos Campos, Tremembé, Aparecida e Queluz. As coletas foram realizadas entre fevereiro e outubro de 2022, abrangendo diferentes períodos sazonais. A quantificação do BPA foi realizada por cromatografia líquida acoplada à espectrometria de massas (LC-MS/MS) com prévia extração em fase sólida, enquanto a atividade estrogênica foi avaliada pelo bioensaio com leveduras BLYES (Bioluminescent Yeast Estrogen Screen). O BPA foi detectado em 50% das amostras analisadas, com concentrações variando entre 11,1 e 116,9 ng L⁻¹. Os maiores valores foram encontrados no município de Queluz, localizado a jusante de áreas industriais e urbanizadas, sugerindo que a contaminação pode estar associada ao lançamento de efluentes industriais e domésticos. A atividade estrogênica também foi positiva em 50% das amostras, com concentrações entre 0,12 e 1,36 ng L⁻¹ de equivalente de estradiol (EEQ). As amostras coletadas em outubro apresentaram os maiores valores de atividade estrogênica, especialmente nos municípios de Tremembé e Aparecida, onde o tratamento de esgoto é inadequado. A análise estatística indicou uma forte correlação entre a atividade estrogênica e o índice de qualidade da água (IQA) (R² = 0,9157), sugerindo que o despejo de esgoto doméstico não tratado é a principal fonte de compostos estrogênicos no rio. No entanto, a correlação entre BPA e IQA foi mais baixa (R² = 0,4282), o que sugere que as fontes industriais também contribuem para a poluição. O BPA, por si só, apresentou baixa correlação com a atividade estrogênica (R² = 0,01783), indicando que outros compostos, como hormônios naturais e sintéticos, podem estar desempenhando um papel significativo nos efeitos endócrinos observados. Além disso, os resultados do IQA mostraram que a qualidade da água era mais comprometida durante a estação chuvosa, evidenciando o impacto do escoamento superficial e da diluição sazonal dos contaminantes. Estes achados reforçam a necessidade de monitoramento contínuo e da implementação de políticas públicas voltadas à melhoria do tratamento de efluentes, visando mitigar os riscos associados aos contaminantes emergentes e garantir a qualidade dos recursos hídricos utilizados para abastecimento humano.