Comparing Chitin and Organic Substrates on the National Tunnel Waters in Blackhawk, Colorado for Manganese Removal

Abstract

Abstract:The National Tunnel is a part of the Central City / Idaho Springs Superfund site. Because passive treatment is an important possibility for removal of contaminants from the water, the USEPA and the Colorado Division of Public Health and Environment (CDPHE) have been sponsoring a bench-scale study of different organic substrates for sulfate-reducing bioreactors (SRBRs). The substrates being tested include ethanol, woodchips and hay, woodchips and corn stover, and crab-shell chitin. After 6-18 months of operation, all of the reactors are showing significant amounts of sulfate reduction. In all of the reactors, Cu and Zn are removed to below their respective ambient water quality criteria of 0.010 and 0.100 mg/L. As is commonly observed in SRBRs, Mn removal is significantly less, with the exception of the chitin reactors. The reason for chitin's superior Mn removal may be the dissolution of calcite from the crab shell. In the chitin reactors, Ca has increased from 210 to 870 mg/L and alkalinity has increased from zero to up to 5,000 mg CaCO 3 / L. Furthermore, the pH of the effluent leaving the chitin systems averages 6.9. In most SRBRs, Mn is precipitated as MnCO 3 and significant removal does not occur until the pH is raised to between 7 and 8. This is the case in the other types of SRBRs being tested at the National Tunnel, as their Mn removal efficiencies have only approached 50 % at pH values ranging from 6.5 to 7.5. However, in the chitin reactors, 86% of the influent Mn is being removed from 21.5 mg/L to an average of 3 mg/L. The high removal is very similar to the removal of Mn in pulsed limestone beds that are maximized for the dissolution of calcite. These chitin reactors have been operating for six months while the other substrate reactors have been operating for over one year.

Biosorption of manganese onto chitin and associated proteins during the treatment of mine impacted water

“…In recent studies, crab-shell chitin has shown relatively high efficiency to remove Mn under reducing conditions from MIW in both laboratory and field studies [7][8][9][10]. This efficient acidity and metal removal may be attributed to the dissolution of chitin-associated carbonates, which are naturally present in the shells of crabs and other crustaceans to provide structural strength [11].…”

Review of Passive Systems for Acid Mine Drainage Treatment

“…Designs that increase the depth of water over the organic layer to a meter or more would be expected to increase flushing effectiveness relative to shallow-water designs, but that expectation has not been tested experimentally. The decreasing effectiveness of Organic substrate material References Easily-available materials-sugars, starch, proteins, oils, liquids Edible oil substrate (EOS), mainly emulsified soybean oil, worked well in lab tests Borden (2004, 2005) Cheese whey added to reactors containing cow manure and pine sawdust greatly improved effectiveness Drury (1999) Ethanol was more satisfactory than cellulosic materials at low temperature Buccambuso et al (2007) Methanol was effective in supporting sulfate reduction of lignite pit water Glombitza (2001) Ethanol and methanol were effective in removing Fe at low pH Tsukamoto et al (2004) Glycerol-methanol waste from production of biodiesel fuel was capable of extensive sulfate reduction Zamzow et al (2006) Crab shell chitin was highly effective Daubert and Brennan (2007), Newcombe and Brennan (2008) Chitin was much more effective than lactate or compost Robinson-Lora and Brennan (2010) Chitin, hay and corn with 20-30 % limestone were more effective than ethanol; chitin was very effective for Mn removal Venot et al (2008) Mussel shells were very effective in AMD treatment either alone or mixed with organic materials Trumm and Ball (2014), Uster et al (2015) Cellulose and hemicellulose materials-manures, compost 85 % pea gravel and 15 % leaf compost worked well for at least 2 years McGregor et al (2000) Municipal compost from wastewater treatment was poor Gibert et al (2004) Sewage sludge and rye grass was better than either alone Harris and Ragusa (2001) Organic soil and ryegrass accomplished good treatment Harris and Ragusa (2001) Mushroom compost, waste paper sludge, and decayed oak chips were better than fresh oak chips and organic soil Cow manure and hay with 30 % limestone were more effective than sawdust and wood chips Smart et al (2008) Composted cow manure mixed with ceramic pellets was effective in removing metals by adsorption Willow and Cohen (2003) Mixtures of materials were better than pure leaf mulch, sheep manure, sewage sludge or cellulose Waybrant et al (1998) Decayed wood shavings, straw, manure and spent brewery grains were very effective in treating low pH, high Fe AMD Romanek (2002a, 2002b) Lignin-hay, straw, woody materials Alfalfa hay was better than straw or timothy hay Bechard et al (1994) Wood shavings, pine bark, and compost plus limestone or mussel shell mixtures worked satisfactorily in lab tests…”

Rapid Alkalinity Generation and Metal Removal From Mine Impacted Water Using Crab-Shell Chitin Under Abiotic Conditions

“…In laboratory microcosms tests using spent mushroom compost, sodium lactate, and crab-shell chitin, the latter was the only substrate capable of promoting significant Mn removal in both live and killed systems (>73%, Robinson-Lora and Brennan, 2008). In field studies, enhanced Mn removal (86%) was observed with crab-shell chitin, compared to other substrates (50% for ethanol, wood chips/hay, wood chips/corn stover; Venot et al, 2008).…”