Co-treatment of acid mine drainage with municipal wastewater: performance evaluation

Abstract

Co-treatment of acid mine drainage (AMD) with municipal wastewater (MWW) using the activated sludge process is a novel treatment technology offering potential savings over alternative systems in materials, proprietary chemicals and energy inputs. The impacts of AMD on laboratory-scale activated sludge units (plug-flow and sequencing batch reactors) treating synthetic MWW were investigated. Synthetic AMD containing Al, Cu, Fe, Mn, Pb, Zn and SO4 at a range of concentrations and pH values was formulated to simulate three possible co-treatment processes, i.e., (1) adding raw AMD to the activated sludge aeration tank, (2) pre-treating AMD prior to adding to the aeration tank by mixing with digested sludge and (3) pre-treating AMD by mixing with screened MWW. Continuous AMD loading to the activated sludge reactors during co-treatment did not cause a significant decrease in chemical oxygen demand (COD), 5-day biochemical oxygen demand, or total organic carbon removal; average COD removal rates ranged from 87-93%. Enhanced phosphate removal was observed in reactors loaded with Fe- and Al-rich AMD, with final effluent TP concentrations<2 mg/L. Removal rates for dissolved Al, Cu, Fe and Pb were 52-84%, 47-61%, 74-86% and 100%, respectively, in both systems. Manganese and Zn removal were strongly linked to acidity; removal from net-acidic AMD was <10% for both metals, whereas removal from circum-neutral AMD averaged 93-95% for Mn and 58-90% for Zn. Pre-mixing with screened MWW was the best process option in terms of AMD neutralization and metal removal. However, significant MWW alkalinity was consumed, suggesting an alkali supplement may be necessary.

Co-treatment of acid mine drainage and municipal wastewater effluents: Emphasis on the fate and partitioning of chemical contaminants

“…To date, a limited number of studies have focused on the effective co-treatment of MWW and AMD [24][25][26]. In particular, Hughes and Gray [27] used activated sludge to treat AMD and for phosphates removal from MWW. Phosphates removal was linked to the high Fe and Al content of the AMD, while metals removal was link to an increase in alkalinity attributed to MWW, which in-turn promoted their precipitation.…”

Influence of type and amount of organic matters on the iron sorption of acid mine drainage onto reclaimed-mining soils

“…Strosnider and Nairn (2010) examined the ability of three treatments: limestone, municipal wastewater, and mixed limestonemunicipal wastewater to reduce heavy metal concentrations in AMD and reported that the application of municipal wastewater was able to reduce As concentrations from 19.4 to 0.34 mg L 1 through the adsorption process. Treatment of AMD with materials containing organic matter (municipal wastewater) is considered to be the best treatment technology for the AMD neutralization and metal removal, in which this technology is able to remove 5284% of Al and 7486% of Fe from the AMD (Hughes and Gray, 2013). Compost resulted from household waste processing may also be utilized to reduce the heavy metal contents in AMD, in which the mechanism for reducing heavy metal content occurs through heavy metal absorption on the surface of the compost (Gibert et al, 2005).…”

Functional Interrelationships of Microorganisms in Iron-Based Anaerobic Wastewater Treatment

“…Carbon dioxide (CO 2 ), sulfate (SO 4 2− ), and nitrate (NO 3 − ) are commonly used electron acceptors in anaerobic biological processes of wastewater treatment [ 6 , 7 , 8 ]. Motivated by the benefits of comanaging acid mine drainage (AMD) and municipal wastewater (MWW), cotreatment of both wastes in natural and engineering systems has previously been evaluated and showed impressive results of removing heavy metals and organic matter [ 9 , 10 , 11 ]. These studies have led to further development of innovative iron-dosed treatment processes [ 12 , 13 , 14 ].…”