RESUMO
Colloidal natural organic matter (NOM) is an important foulant to low-pressure membranes (LPMs) employed in drinking water treatment. Removal of colloidal NOM by magnetic ion exchange (MIEX), coagulation, and integrated MIEX and coagulation was investigated in this study to determine the relationship between colloidal NOM removal and membrane fouling reduction. The results showed that coagulation did not selectively remove colloidal NOM and the optimal coagulant dose was primarily determined by the concentration of humic substances. Comparatively, MIEX pretreatment preferentially removed humic substances and reduced the coagulant dose needed for colloidal NOM removal as a result of coagulation stoichiometry. A matched-pair analysis showed that integrated MIEX and coagulation pretreatment at much lower coagulant doses was as effective as coagulation in reducing membrane fouling. It is concluded that integrated MIEX and coagulation is potentially a viable pretreatment approach to reduce membrane fouling and in general removal of colloidal NOM in feedwater is an effective approach for membrane fouling control and should be considered in the research, development, and application of novel LPM-based treatment processes.
Assuntos
Membranas Artificiais , Purificação da Água/instrumentação , Purificação da Água/métodos , Troca Iônica , MagnetismoRESUMO
BACKGROUND: Commercially available hemostatic-adhesive has the risk of disease transmission because it is derived from a plasma component. The purpose of this study is to manufacture a new hemostatic adhesive and evaluate its performances. METHODS: Two atelocollagen-based hemostatic adhesives were produced and named as Bleestop A (2% esterified atelocollagen in 75% ethanol + 1% CaCl(2) + 0.71% DOPA + 0.1% tranexamic acid in DW) and Bleestop B (2% esterified atelocollagen in DW + 1% CaCl(2) + 0.71% DOPA + 0.1% aminocaproic acid in DW). These are compared with the negative control group (no adhesives used group) and the positive control group (Tissucol Duo Quick group). The adult male Sprague-Dawley rat model was adopted and the hemostatic-adhesion activities of each group were assessed by the adhesion strength test and the morphologic features of adhesion. The liver tissues were used. Histologic assessment of adhesion was accessed using light microscopy. RESULTS: Bleeding was controlled immediately after application of Bleestop A and partial adhesion was observed after 30 s. More than 95% area of the resected surface attached after 1 min. In Bleestop B, partial adhesion was observed after 30 s. More than 95% area of the resected surface was attached after 45 s. Histologic evaluation showed that Bleestop A and B mediated organized adhesion rapidly between both resected tissue surfaces. The adhesion strength of Bleestop A and B was better than the negative control group and showed same adhesion strength as the positive control group after 3 min. CONCLUSION: Bleestop A and B showed significant hemostasis and adhesion capability within 1 min. They are comparable to the positive control group.