Recycled concrete aggregate coated with quaternary ammonium compounds for water disinfection

Abstract

Growing demand for point-of-use water treatment including greywater recycling as well as appropriate disinfection without formation of harmful disinfection byproducts (DBPs) calls for new methods of efficient microbial control. In recent years, antimicrobial nanomaterials (NMs) have been widely studied as a potential alternative to traditional chlorine disinfection, yet concerns over their releases to environments and subsequent impacts have limited their use on a large scale. In this work, recycled concrete aggregate (RCA) was proposed as a sustainable and environmentally friendly disinfecting substrate for water disinfection by coating with a composite of silica-quaternary ammonium compound (Fixed-Quat). Two different types (gel and particle) of Fixed-Quat were applied to RCA, and their adherence and antimicrobial activities were compared each other. When using E. Coli as a model bacterial pathogen, the Fixed-Quat gel and particle coated RCA materials showed similar and effective microbial inactivation performance with a rate of 2.0 9 10 -3 (gel) and 1.82 9 10 -3 (particle) log reduction cm -2 min -1 . By potentially eliminating regulated DBPs formation and minimizing release of NMs into the environment, the antimicrobial coated RCA would be a promising and sustainable alternative to conventional disinfection methods in engineered aquatic systems. KeywordsDisinfection Á Fixed-Quat Á Recycled concrete aggregate (RCA) Á Silica-quaternary ammonium (Quat) Editorial responsibility: Binbin Huang. J. Church and H. Kannan are equally contributing co-first authors. W. H. Lee and S. Santra are equally contributed.

A pragmatic review paper on the use of recycled aggregates in concrete

“…After that, they were dried for a total of two days at a temperature of fifty degrees Celsius. Sputter coaters were utilised in order to provide the components with a gold finish [20].…”

Dissimilar surface treated recycled coarse aggregate in concrete

“…The following methods are used to treat the recycled aggregate: thermal treatment (7), chemical treatment (10), mechanical scrubbing treatment (7), carbonation and wrapping methods (14), calcium metasilicate slurry (30), cement treatment (59), mineral additives (25), modified concrete mixer (11), warm mix asphalt and hydrated lime (21), CO 2 curing technique (14), silica gel techniques (60), waste oil and asphalt emulsion (15), nano materials (61), super plasticizers (9), bio-deposition approach (28), silane-based water repellent (62). All of these methods are adopted to enhance the surface of recycled aggregate.…”

“…Stężenie kwasu, większe od 3%, powoduje efekt opóźniający, w wytwarzaniu betonu (16)(17)(18). Do oczyszczania kruszywa z recyklingu stosuje się następujące metody: obróbka termiczna (7) i chemiczna (10), obróbka mechaniczna metodą szorowania (7), metody karbonizacji (14), zawiesina metakrzemianu wapniowego (30), obróbka cementem (59), dodatki mineralne (25), stosowanie mieszalnika betonu (11), domieszki mineralne (25), ciepła mieszanka asfaltowa i wapno hydratyzowane (21), technika twardnienia za pomocą CO 2 (14), stosowanie żelu krzemionkowego (60), stosowanie emulsji z oleju odpadowego i asfaltu (15), nano-materiały (61), superplastyfikatory (9), metoda składowania (28), hydrofobizacja z zastosowaniem krzemowodorów (62). Wszystkie te metody są stosowane w celu poprawy powierzchni kruszywa, z recyklingu.…”