Treatment of Final Effluent using Hydrochar Derived AC

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This project investigated the viability of using waste derived adsorbents to remove heavy metals from wastewater effluent. The performances of an activated carbon produced by pyrolysis of sludge hydrochar(generated from enhanced hydrothermal polymerisation of combined primary and waste activated sludge) was investigated. Laboratory scale tests and pilot scale adsorption column tests were conducted to evaluate the performance of the hydrocharactivated carbon (HAC) and C-GAC in removing heavy that are included in the South African National Standard (SANS) 241 for potable water. Adsorption kinetics and isotherms were determined for a mono-element solution containing Pb (II) ions for both C-GAC and HAC. The results showed that the performance of HAC was similar to C-GAC with both having an adsorption capacity and removal of Pb (II) of 1.5 mg/g and 99%respectively. Further laboratory scale adsorption tests and pilot scale column tests assessed the performance of the activated carbons in removing heavy metals from secondary clarifier effluent from a BNR activated sludge plant. The studies indicated that performance of HAC and C- GAC was closely similar for the elements that were above the detection limit (Fe, Ni, Mn and Zn) with removals above for 80% The adsorption experiments showed an order of adsorption of Fe> Ni> Mn > Zn for both C-GAC and HAC at pilot scale.

The study results indicate that HAC has potential to be used as an adsorbent in the tertiary treatment of final effluent from WWTPs for reuse.