A produção de H2S (sulfeto de hidrogênio) é um dos principais problemas na indústria do petróleo, sendo esta uma das causas da corrosão de tanques de estocagem e tubulações. Essa produção é possibilitada devido à injeção de água do mar durante o processo de recuperação secundária do petróleo, onde alguns micro-organismos presentes nessa água, tais como as bactérias anaeróbias heterotróficas totais (BANHT) e as bactérias redutoras de sulfato (BRS), que promovem a redução do sulfato a sulfeto. Atualmente, o método de quantificação destes micro-organismos é a técnica do Número Mais Provável (NMP) que estima o resultado em aproximadamente 28 dias. No presente trabalho foi utilizada a metodologia da produção semi-contínua de sulfeto biogênico pelo período de 15 dias, com o intuito de correlacionar com os resultados das quantificações de BANHT e BRS através da técnica convencional do NMP. Foram analisadas amostras de diferentes procedências da indústria do petróleo, apresentando variação na salinidade de 0 a 16 g.L-1. O objetivo deste procedimento foi avaliar as velocidades específicas e instantâneas de produção de H2S, sugerindo, desta forma, quais amostras apresentam maior potencial para a produção biogênica de sulfeto e em quais condições essa produção se dá. Observou-se que em todas as amostras a geração do H2S se dá de forma crescente até a estabilização desta produção, sendo esta obtida quase sempre em seis dias (144h) do crescimento microbiano. A produção do sulfeto biogênico se deu de forma mais intensa nas amostras do fundo de tanque de estocagem de óleo e da água de formação. A quantificação das BANHT e das BRS foram avaliadas pelo método do NMP de acordo com a tabela de Harrigan, a qual subestima a população microbiana, desconsiderando erros provenientes da técnica / The production of H2S (hydrogen sulfide) is a major problem in the oil industry, which is a cause of corrosion of pipes and storage tanks. This production is made possible due to seawater injection during the secondary oil recovery process where some microorganisms present in this water, such as total heterotrophic anaerobic bacteria (THAB) and sulphate-reducing bacteria (SRB) that promote reduction of sulfate to sulfide. Currently, the method of quantification of these microorganisms is the technique of the Most Probable Number (MPN) which estimates the results in about 28 days. The present study used the methodology of semi-continuous production of biogenic sulfide by 15 days period, in order to correlate with the measurements results of BANHT and BRS through the conventional technique of MPN. There were several samples analyzed from different origins in the oil industry, with variations in salinity from 0 to 16 g.L-1. The purpose of this procedure was to evaluate the specific speeds and instantaneous H2S production, suggesting thereby that samples had increased biogenic sulfide production and this production conditions which occurs. It was observed that all samples in the generation of H2S occurs incrementally until stabilization of this production, these being almost always obtained in six days (144h) of microbial growth. The production of biogenic sulfide occurred more intensely in the samples of oil storage tank bottom and formation water. The quantification of SRB and THAB were evaluated by the MPN method according to Harrigan table, which underestimates the microbial population, disregarding errors arising in the art

A produção de H2S (sulfeto de hidrogênio) é um dos principais problemas na indústria do petróleo, sendo esta uma das causas da corrosão de tanques de estocagem e tubulações. Essa produção é possibilitada devido à injeção de água do mar durante o processo de recuperação secundária do petróleo, onde alguns micro-organismos presentes nessa água, tais como as bactérias anaeróbias heterotróficas totais (BANHT) e as bactérias redutoras de sulfato (BRS), que promovem a redução do sulfato a sulfeto. Atualmente, o método de quantificação destes micro-organismos é a técnica do Número Mais Provável (NMP) que estima o resultado em aproximadamente 28 dias. No presente trabalho foi utilizada a metodologia da produção semi-contínua de sulfeto biogênico pelo período de 15 dias, com o intuito de correlacionar com os resultados das quantificações de BANHT e BRS através da técnica convencional do NMP. Foram analisadas amostras de diferentes procedências da indústria do petróleo, apresentando variação na salinidade de 0 a 16 g.L-1. O objetivo deste procedimento foi avaliar as velocidades específicas e instantâneas de produção de H2S, sugerindo, desta forma, quais amostras apresentam maior potencial para a produção biogênica de sulfeto e em quais condições essa produção se dá. Observou-se que em todas as amostras a geração do H2S se dá de forma crescente até a estabilização desta produção, sendo esta obtida quase sempre em seis dias (144h) do crescimento microbiano. A produção do sulfeto biogênico se deu de forma mais intensa nas amostras do fundo de tanque de estocagem de óleo e da água de formação. A quantificação das BANHT e das BRS foram avaliadas pelo método do NMP de acordo com a tabela de Harrigan, a qual subestima a população microbiana, desconsiderando erros provenientes da técnica / The production of H2S (hydrogen sulfide) is a major problem in the oil industry, which is a cause of corrosion of pipes and storage tanks. This production is made possible due to seawater injection during the secondary oil recovery process where some microorganisms present in this water, such as total heterotrophic anaerobic bacteria (THAB) and sulphate-reducing bacteria (SRB) that promote reduction of sulfate to sulfide. Currently, the method of quantification of these microorganisms is the technique of the Most Probable Number (MPN) which estimates the results in about 28 days. The present study used the methodology of semi-continuous production of biogenic sulfide by 15 days period, in order to correlate with the measurements results of BANHT and BRS through the conventional technique of MPN. There were several samples analyzed from different origins in the oil industry, with variations in salinity from 0 to 16 g.L-1. The purpose of this procedure was to evaluate the specific speeds and instantaneous H2S production, suggesting thereby that samples had increased biogenic sulfide production and this production conditions which occurs. It was observed that all samples in the generation of H2S occurs incrementally until stabilization of this production, these being almost always obtained in six days (144h) of microbial growth. The production of biogenic sulfide occurred more intensely in the samples of oil storage tank bottom and formation water. The quantification of SRB and THAB were evaluated by the MPN method according to Harrigan table, which underestimates the microbial population, disregarding errors arising in the art

In recent years, the excessive specific conductance (SC) of Appalachian coal mining runoff waters has become a parameter of concern with the EPA due to its negative effect on aquatic life and water quality. In order to comply with the EPA guidance suggesting an effluent SC of 500 µS/cm, the Appalachian Research Initiative for Environmental Science (ARIES) Center at Virginia Tech requested that testing be done to determine the most effective technologies for reduction of SC. Runoff water was collected from two sites in southwestern Virginia and characterized to determine the source of SC in the water. The main contributing ions were determined to be Na⁺, Mg²⁻, Ca²⁺, and SO₄²⁻. Testing was performed to assess the possibility of using the speciation software, MINEQL+, with a set of empirical equations which predict SC using ionic composition for natural waters with a low to medium SC. The physicochemical treatment methods tested were ion exchange, excess lime-soda softening, and the Cost Effective Sulfate Removal (CESR) process. Both cation (H⁺ exchanger) and anion (Cl⁻ exchanger) exchange media were tested separately in batch reactors, which resulted in a higher effluent SC than initial SC. The softening method investigated, excess lime-soda softening, also resulted in increased SC levels because non-carbonate hardness levels were high and carbonate concentrations were low. The CESR process successfully lowered SC from 1,500-2,500 µS/cm to below the proposed EPA limit of 500 µS/cm. The success of this process was due to its ability to remove more than 85% of the calcium, magnesium, and sulfate from the water, which together accounted for more than 90% of ions in the source water. / Master of Science / In recent years, mining activities have generated large amounts of unweathered rock from blasting. This rock, which is often stored in valleys near the blasting sites, releases salts into water that passes over the rocks when it rains. The salty water flows into nearby streams populated with freshwater fish and other organisms that suffer when their environmental conditions are changed. The Appalachian Research Initiative for Environmental Science (ARIES) Center at Virginia Tech requested that testing be done to determine which engineering techniques would be most effective for reduction of these salts. The amount of salt in the water is measured by specific conductance (SC), which measures how well the water conducts electricity. Testing was also done to determine which types of salts were in the water; the results showed that the largest contributors were sodium, magnesium, calcium, and sulfate ions. Three engineering techniques were investigated for removal of the contributing ions: ion exchange, softening, and the Cost Effective Sulfate Removal (CESR) process. Two types of ions exchange, one that targeted the positive ions (cation exchange) and one that targeted the negative ions (anion exchange), were tested. Both forms of ions exchange raised the SC to a higher concentration than the original water. Softening had a similar effect because one of the chemicals added during the process released additional sodium ions into the water. Finally, the CESR process was able to successfully reduce the SC below the limit proposed by the EPA as safe for stream life. This was due to the large reduction of three of the four major ions that was achieved during the CESR process.