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Sludge reclaimed from drinking water treatment plant was carbonized and chemically activated by K 2 CO 3 and CH 3 COOH. The proposal was to evaluate its adsorbent properties as a low-cost alternative material for metal ion remediation. Morphological, physicochemical, and chemical characteristics have been presented and comprehensively discussed. Main findings revealed a surface area rich in mesopores and loaded with weakly acidic functional groups, also presenting an eroded aspect. Carbonization of the sludge's organic content increased the concentration of nitrogenic and oxygenated functional surface groups. Chemical activation by K 2 CO 3 and CH 3 COOH increased adsorption and desorption capacity, pore volume, and pore size by two, three, and over tenfolds, respectively. Uptake of cations increased by 51% and, for anions, around 27%. Association of carbonization with sequenced activation processes converted drinking water treatment plant sludge into an excellent and promising alternative adsorbent material. and activation is available on the literature. Considering the lack of studies regarding the production of activated carbons from DWTP sludge, this study reports the conversion of this widely available feedstock through carbonization and chemical activation.Activated carbons (AC) are scientifically known for having high sorption capacity for different types of chemical species [28], a characteristic of an adsorbent material with large surface area, porous structure, and chemically active surface [29]. Additionally, the high concentration of metals in raw water treatment sludge and, consequently, in its char, may also improve ion-solution interaction. Activated carbons usually have their surface functional groups bonded to complex aromatic rings, behaving similarly to aromatic hydrocarbons [30]. As so, a thermochemical modification would then improve these characteristics in the AC's surface chemistry, as a function of the usage purpose. Overall, the chemical activation of carbonized materials'

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Activated carbon is a well known amorphous adsorbent for hydrophobic pollutants, having the ability to take in its porous structure molecules of very different sizes. Portalegre Polytechnic Institute has a pilot plant for biomass gasification for syngas production, the residues of which need remediation. The syngas production process produces tar rich liquid condensates and powdered carbon as main residues. The powdered carbon is in fact activated carbon once it results from partial combustion at high temperatures and so it can be used as an adsorbent for pollutant removal from any effluent. Condensates resulting from gasification are coloured and strongly odoured residues; rich in hydrocarbon contaminants usually known as tars. In this work, powdered carbon residue was used to adsorb the contaminants present in the condensate residue produced in the process. The adsorption process was shown to be highly efficient in the removal of odour and colour from gasification condensates and the results were not very much different from the ones obtained for commercial activated carbon. After being used for adsorption, the carbon residue can be reburned in the gasification plant (which also needs coal for the heating start up procedure) to promote a final destruction process of the adsorbed contaminants with production of freshly activated carbon.