No abstract

No abstract

Microbial souring (H2S production) in porous media was investigated in an anaerobic upflow porous media reactor at 60 degrees C using microbial consortia obtained from oil reservoirs. Multiple carbon sources (formate, acetate, propionate, iso- and n-butyrates) found in reservoir waters as well as sulfate as the electron acceptor was used. Kinetics and rates of souring in the reactor system were analyzed. Higher volumetric substrate consumption rates (organic acids and sulfate) and a higher volumetric H(2)S production rate were found at the from part of the reactor column after H(2)S production had stabilized. Concentration gradients for the substrates (organic acids and sulfate) and H(2)S were generated along the column. Biomass accumulation throughout the entire column was observed. The average specific sulfate reduction rate (H(2)S production rate) in the present reactor after H(2)S production had stabilized was calculated to be 11062 +/-2.22 mg sulfate-S/day g biomass.

No abstract

No abstract

No abstract

Removal of nitrate from mining and other industrial and municipal effluents is often required to meet water discharge limits, and state and federal nondegradation standards for surface water and groundwater. To meet the need to remove nitrate from low-temperature waters, a technology termed the Anoxic Biotreatment Cell (ABC) was developed by Hydrometries, Inc. beginning in 1995. A large demonstration-scale ABC operating at a metal mine in Montana since early 1996 has consistently removed over 90 percent of the incoming nitrate when operated at design conditions. Typical results were 95 percent nitrate removal at a flow rate of 130 gallons per minute (gpm) and a water temperature of 12°C. The reactor also operated successfully at flow rates as high as 160 gpm and water temperatures as low as 2'C. The initial reactor was modified in 1997 to reduce downtime and to increase capacity to approximately 400 gpm. A 200-gpm ABC to treat water with higher nitrate concentrations (llO mg/L as N) has successfully operated at another mine site since 1997. Removal of low concentrations of metals and sulfate have also been demonstrated in a full-scale ABC application. The ABC has removed selenium in continuousflow column experiments, from approximately 1.2 mg/L to less than 0.1 mg/L. The ABC is less costly than alternative treatment technologies because it: a) is simple in design, construction and operation, b) is effective at cold water temperatures, and c) does not generate a waste stream. The system can be designed to treat a variety of flows, concentrations, water temperatures and water qualities.

Abstract:Many waters associated with mining and mineral processing contain high concentrations of arsenic, and effluent typically must meet increasingly stringent. human health standards. A new proprietary technology for arsenic removal has been developed by Peter F. Santina to cost-effectively meet these discharge limits. Hydrometries, Inc. has performed, under contract to Peter F. Santina, further lab tests to prove and test limits of the efficacy of the process. In the sulfur-modified iron (SM!) process, arsenic is removed by an iron/sulfur matrix. Arsenic concentrations below 0.005 mg/1. have been obtained using SMI in jar tests and column tests, and the iron/sulfur residue has passed the U.S. EPA Toxicity Characteristic Leaching Procedure (TCLP) test. A 10-gpm federally-funded pilot test is underway to further develop this promising technology. The purpose of pilot testing is to identify specific design parameters and operational procedures which can be used for full-scale production application of the SM! process. Projected operating costs for SM! are lower than alternative arsenic removal technologies such as iron salt addition, reverse osmosis and activated alumina. Cost savings would increase proportionally with higher flow rates and higher arsenic concentrations. The SM! process is potentially very promising for simple, cost-effective treatment of mining and other industrial effluents, drinking water and other arsenic-containing waters. Additional