An evaluation of clay minerals as support materials in anaerobic digesters

The use of different clay minerals as support materials in anaerobic digestion has been studied. The support materials were evaluated in a batch microdigester and their effect on the digestion process was measured at the beginning of the process (startup) and at an intermediate point of the digestion process when the maximum differences between support materials were observed (working digester). All the systems with support were more efficient than the control (support-free). The following order of purification was established: STARTUP: Bentonite > talc > vermiculite > nontronite > montmorillonite > pyrophyllite > stevensite > sepiolite. WORKING DIGESTER: Sepiolite > stevensite > talc > nontronite > bentonite > montmorillonite > vermiculite > pyrophyllite. Bentonite, montmorillonite, talc and vermiculite were favourable for startup, as they rapidly released Ca2+ or Mg2+ to the medium. The best COD removal efficiencies were obtained with sepiolite and stevensite which release Mg2+ progressively to the medium. The presence of Fe2+, Co2+ and Ni2+ in the structure of the mineral stimulated anaerobic digestion.Peer Reviewe

An evaluation of clay minerals as support materials in anaerobic digesters

The use of different clay rninerals as support in anaerobic digestion has been studied: The suppon materials were evaluated in a batch microd.igester and their effect in the digestion process was measured ar the beginning of the process (scartup) and at an intermed iate point of the digescíon process when the maxim um differences between supporc rnaterials were observed (working digester). Ali the systems with support were more efficient than the control (support-free). The follow ing arder of purification was established: STARTUP: Bentonite > tale > vermicul ite > nontronite > montmori llonite > pyrophyll ite > stevensire > sepiol ite. WORKI NG DIGESTER: Sepiolite > stevensite > tale > nontronite > bentonite > rnoncmorillonice > ver m icu l ice > pyrophyllite. Bentonite, montmorillonite, tale and vermieulite were favourable for startup, as they rapidly reteased Ca1 or MgH to che medium. The best COD removal efficiencies were obtained with sepiol ite and scevensite which release MgH progresively to the med ium . The presence of FeH , Co2 • and Nii... in the structure of che mineral stimulated anaerobic digescion.DGICYT AMB95-0904Junta de Andalucía PAI-RNM16