Application of sludge-based carbonaceous materials in a hybrid water treatment process based on adsorption and catalytic wet air oxidation

Abstract

This paper describes a preliminary evaluation of the performance of carbonaceous materials prepared from sewage sludges (SBCMs) in a hybrid water treatment process based on adsorption and catalytic wet air oxidation; phenol was used as the model pollutant. Three different sewage sludges were treated by either carbonisation or steam activation, and the physico-chemical properties of the resultant carbonaceous materials (e.g. hardness, BET surface area, ash and elemental content, surface chemistry) were evaluated and compared with a commercial reference activated carbon (PICA F22). The adsorption capacity for phenol of the SBCMs was greater than suggested by their BET surface area, but less than F22; a steam activated, dewatered raw sludge (SA_DRAW) had the greatest adsorption capacity of the SBCMs in the investigated range of concentrations (<0.05 mol L(-1)). In batch oxidation tests, the SBCMs demonstrated catalytic behaviour arising from their substrate adsorptivity and metal content. Recycling of SA_DRAW in successive oxidations led to significant structural attrition and a hardened SA_DRAW was evaluated, but found to be unsatisfactory during the oxidation step. In a combined adsorption-oxidation sequence, both the PICA carbon and a selected SBCM showed deterioration in phenol adsorption after oxidative regeneration, but a steady state performance was reached after 2 or 3 cycles.

Removal of Phenolic Compounds from Water Using Sewage Sludge-Based Activated Carbon Adsorption: A Review

“…He reported S BET and micropore volume of 265 m 2 /g and 0.11 cm 3 /g when the sludge was activated at 838 °C and 80 min contact time. Other related studies conducted under similar activation conditions reported comparable values of obtained surface areas [ 42 , 53 , 54 ]. Compared to steam activation, CO 2 proved promising in producing better textural properties of SBAC.…”

“…However, the low S BET and dominant mesoporous structure was attributed to high ash content of sludge that limits the development of microporous structures. In another study, Julcour Lebigue et al [ 42 ] carried out carbonization of two sludges with ash contents of 20% and 40% at 900 °C among which which the latter yielded the highest S BET of 180 m 2 /g. Numerous studies have also corroborated similar behaviors [ 43 , 44 ].…”

“…It is apparent that the steam activated carbons don’t only exhibit enhanced textural properties but also produce surface functional groups that result in improved PC adsorptive capacity. For example, the S BET and adsorption capacity of carbonized DSS increased from 180 m 2 /g to 265 m 2 /g and 131 mg/g to 150 mg/g when further activated using steam, respectively [ 42 ]. Recent studies have claimed a similar behavior [ 20 , 22 ].…”

Assessment and Modeling of a Sequential Process for Water Treatment—Adsorption and Batch CWAO Regeneration of Activated Carbon

“…The AD-OX process was first described and assessed for phenol/4-hydroxybenzoic acid mixture in a large reactor used for preliminary scale up 20 . In order to reduce the adsorption time for many successive runs, a small automated reactor was built up and tested with various effluents and activated carbons: examples are reported by Krou 22 for phenol and tartrazine solutions, as well as real effluent issued from biological treatment of industrial wastewater up to 20 cycles, and Julcour Lebigue et al 21 using commercial AC and carbonaceous materials issued from sewage sludge. Similar general trends were observed with all these systems.…”

Toluene, Methanol and Benzaldehyde Removal from Gas Streams by Adsorption onto Natural Clay and Faujasite-Y type Zeolite

“…25 In this perspective, different alternative adsorbents are desirable to overcome these kinds of problems. [26][27][28] In this context, natural clays appear as interest natural adsorbents to clean polluted air, since their application could result in a cost-effective process for VOCs removal. Natural clays are quite abundant and their low costs are likely to become strong adsorbent candidates for the removal of VOCs from air.…”