Valorization of undervalued aluminum-based waterworks sludge waste for the science of “The 5 Rs’ criteria”

Abstract

Alum sludge (AS) is an underrated by-product waste resulted from treating raw water through conventional water treatment plants. Water is attained from various reservoirs such as rivers and aquifers, and it may contain a wide variety of contaminants as drinking water processing systems produce “waste” sludge as a residual material that causes significant environmental issues. Hence, numerous efforts aimed to sustainable reuses of such sludge. This article illustrates the beneficial reuses of the aluminum-based sludge to close the loop between the sludge waste generation and the sustainable environment with providing past, current and updated knowledge with the introduced uses with their advantages and challenges. Alum sludge as a resource not as a “waste” for reuse facilities is considered a value-added alternative for management achieving the legislation requirements and proposing “end-of-waste” concept. 5Rs, including “Reduce, Reprocess, Reuse, Recycle and Recover,” are providing sustainable solution to fulfill present and future aspects for green environment and safe sludge disposal. In this regard, now, it is essential to focus and adopt the 5Rs criteria for the concept of circular economy that replaces the “end-of-life” principal with restoration.

Construction of a hetero-junction recyclable composite photocatalyst from aluminum-based waste/magnetite for efficient carbamate insecticide oxidation

“…Since aluminum-based sludge is rich in aluminum with other elements and magnetite in the composite is rich with Fe 2+/3+ , several oxidation reactions could occur in the aqueous environment. 44 The general trend of an aluminum-based Fenton reaction mechanism is that an Al 3+ superoxide complex of the type [Al(O 2 )(H 2 O) m (OH) n ] ( q −1) is formed from [Al(H 2 O) m (OH) n ] q hydrolytic species. Such species were demonstrated via a cluster-continuum methodology to have two shells of explicit water molecules.…”

“…Those non-selective ˙OH radicals attack the carbamate molecules and strongly oxidize them. But, further increasing the AS400 results in a decline in the oxidation efficiency as a result of the shading effect of the AS400 from the turbid solution, on the UV illumination since AS400 comprises inorganic materials 44 that obey UV transmittance when it is in excess. Besides, excessive metal ion concentration results in it acting as an ˙OH radical scavenger rather than a generator.…”

“…Since aluminum-based sludge is rich in aluminum with other elements and magnetite in the composite is rich with Fe 2+/3+ , several oxidation reactions could occur in the aqueous environment. 44 The general trend of an aluminum-based Fenton reaction mechanism is that an…”

Compendium data and preliminary results based on alum sludge and gravel continuous fixed-packed-bed column substrate as sustainable practice for constructed wetland development in northern Egypt

“…But, detailed and more published studies are related to phosphorus removal from various wastewater effluents and types, their equilibrium isotherm, kinetic analysis and the effect of system parameters have been studied. The presence of amorphous aluminium nature in the alum sludge maximizing its affinity to adorb phosphorous anions from contaminated streams [51]. Alum sludge sorption capabilities are related to the particle size, surface area and surface charge of the alum sludge particles.…”

Multivariate-Parameters Effect of Dewatered Aluminium-Based Sludge in Catalytic Oxidation into Wastewater Treatment with A Special Strategy for Solar Energy Application

“…Textile dye wastewater has been one of the health and environmental issues in developing economical countries due to its high COD and colour with non-biodegradable organics from textile dyestuffs. As a result, numerous methods for treating textile wastewater have been developed, including biological chemical, physico-chemical and advanced oxidation processes [1][2][3][4]. In contrast, Fenton is often regarded as the most appropriate technique of destruction not only for ternary treatment but also for enhancing the biodegradability of dye wastewater for subsequent conventional treatment [5,6].…”