Anaerobic pretreatment of hazardous waste leachates in publicly owned treatment works

Abstract

Feasibility studies have been completed for an anaerobic pretreatment system designed to treat hazardous waste leachates in publicly owned treatment works. The system was designed to mitigate many of the problems associated with conventional aerobic treatment of these wastes and other types of dilute waterborne hazardous wastes. In this new approach, a contact/sorption stage consisting of an expanded bed of granular activated carbon (GAC) with an attached anaerobic biomass was used as a pretreatment device after primary clarification before the aerobic treatment portion of the plant. This sorption stage was intended to reduce pass‐through of toxics, retaining them for subsequent treatment in a separate anaerobic stabilization reactor. The organic‐rich GAC/biomass bed from the sorption stage was exchanged with stabilized GAC biomass from the anaerobic stabilization stage, conserving the GAC in the system. Two 87‐L/d bench‐scale systems were operated for 332 days, one treating unspiked primary effluent and one treating primary effluent spiked with 5% landfill leachate and 14 hazardous organic compounds. In the spiked system, removals in the sorption stage were the highest for the aromatic compounds. Five of the six aromatics added were removed at over 95% and the sixth, phenol, had an 85% removal. Removals of chlorinated aliphatic compounds ranged from 52% for methylene chloride to 95% for trichloroethylene. Removals of phthalate compounds were approximately 60%. Removals of ketones ranged from 24% for acetone to 93% for methyl isobutyl ketone. Chemical oxygen demand removals remained at 40% to 50% throughout the year‐long study in both systems.

Treatment of organic synthesis wastewater using anaerobic packed bed and aerobic suspended growth bioreactors

“…Because of the low TSS concentration and because of the presence of VOCs in the wastewater, anaerobic biofilters with granulated activated carbon (GAC) and with tezontle (volcanic porous stone widely available in Mexico) were also tested (Nacheva et al, 2003). GAC-reactors showed high effectiveness and stability, in concordance with the reported advantages of using GAC as biofilm attachment media for treatment of toxic or inhibitory wastewater (Suidan et al, 1993;Kupferle et al, 1995;Monteleb et al, 2001). The tezontle was also shown to be a good packed bed media, but process effectiveness and stability were lower.…”

Physicochemical processes

“…Results indicated that the two-stage system may be an effective 2,4-DNT treatment method. Kupferle et. al.…”

Treatment of chemical-pharmaceutical wastewater in packed bed anaerobic reactors

“…Many materials can be used as attachment media for the microbial population in the packed bed reactors and their characteristics are important for successful performance and operation. There are reports in the literature concerning the successful use of granular activated carbon (GAC) in fluidized bed anaerobic reactors to remove catechols (Suidan et al, 1980), polycyclic compounds (Wang et al, 1984) and phenols (Wang et al, 1986), in the treatment of wastes from the gasification of carbon (Suidan et al, 1983;Fox et al, 1988) and from leachates (Suidan et al, 1993;Kupferle et al, 1995). The presence of xenobiotic compounds in the chemical-pharmaceutical effluents justifies the use of GAC in the anaerobic packed bed reactors as well.…”