ABSTRACT
Objective To obtainthe baseline data of the gross α and gross β radioactivity levels in environmental samples and foods by the monitoring and analyzing the radioactivity levels in drinking water, aerosols and commercial foods in Nanjing City. Methods 15 types of samples, including water source, produced water, aerosol, chicken, pork, stalk vegetable, root vegetable, fresh milk, leafy vegetable, flour, fruits, rice, tea, fish and crab were collected. After pretreatment, LB4008 four-channel low background α and β measuring instrument was used to measure the gross α and gross β radioactivity concentrations. Results The gross α and gross β activity concentrations of source water and produced water in Nanjing from 2016 to 2019 were lower than the national limits. The gross α and gross β activity concentrations in the source water were significantly higher than those of the produced water (P < 0.05). The mean activity concentration range of gross α and gross β in aerosol were 0.16～0.98 mBq/m3 and 0.14～2.15 mBq/m3 from 2016 to 2019, and with no statistical difference in difference samples (P > 0.05). The gross α and gross β activity concentration range of foods were 0.10～17.00 Bq/kg and 22.20～187.20 Bq/kg, of which the gross α and gross β activity concentration in tea were significantly higher than that of other kinds of foods (P < 0.05). Conclusion The radioactivity level in drinking water, atmospheric aerosols and foods in Nanjing were not contaminated by radioactive substances, and the gross α and gross β were relatively stable.
ABSTRACT
Aim: To determine the biocidal efficacy of THPS based biocides currently used in oil fields to control souring and corrosion. Methodology: By direct monitoring of inhibition of cell growth and inhibition of microbial functional group activities such as the ability to reduce sulfate and generate sulfide by sulfate reducing bacteria (SRB), reduce nitrate to nitrite by heterotrophic nitrate reducing bacteria (hNRB) and oxidation of sulfide and reduction of nitrate by sulfide oxidizing, nitrate reducing bacteria( so-NRB) using CSB-K medium. Results: We observed that higher doses of THPS (>400 ppm) was required to considerably inhibit the ability of SRB to reduce sulfate and generate hydrogen sulfide. It was also observed that the activities of SRB were more affected by the THPS biocides than those of hNRB and so-NRB. Conclusion: We conclude that SRB may have developed low level microbial resistance to THPS based biocides as higher doses are required to inhibit their activities. It is therefore recommended that THPS should be used in combination with other biocides or metabolic inhibitors for it to be effective at lower concentrations.
ABSTRACT
Aim: To determine the level of inhibition of microbial functional group activities such as the ability to reduce sulfate to sulfide by sulfate reducing bacteria (SRB), reduce nitrate to nitrite by the heterotrophic nitrate reducing bacteria (hNRB), and oxidize sulfide and reduce nitrate by sulfide oxidizing, nitrate reducing bacteria (so-NRB) by some oxidizing biocides like chlorine, bromine and ozone. Methodology: Samples of the oxidizing biocides were obtained from Microcheck and the inhibition of some functional group activities in produced and injection water samples were determined using CSB-K medium. Results: Ozone was found to be more effective than chlorine and bromine in the inhibition of functional group activities at lower concentrations. Conclusion: More research effort is required to see if ozone can work in synergy with other biocides to improve on its efficiency.
ABSTRACT
O gerenciamento da água produzida (AP) de petróleo se constitui em um enorme desafio para as empresas petrolíferas. As alternativas usualmente adotadas para o seu destino são o descarte, injeção e o reúso. Em todos os casos é necessário tratamento da AP, a fim de evitar danos ao meio ambiente e às instalações de produção ou a fim de permitir o seu reúso sem causar prejuízos aos processos nos quais a AP será utilizada. Os processos de separação por membranas (PSM) têm se mostrado capazes de tratar efluentes que apresentam elevados teores de óleo em emulsão e de partículas com tamanhos médios e pequenos, competindo, assim, com tecnologias de tratamento mais complexas, tais como flotação. O objetivo deste artigo foi apresentar uma revisão sobre o tratamento de AP utilizando os PSM discutindo os principais aspectos da AP e os aspectos conceituais dos PSM, com ênfase para sua aplicação para remoção de óleo da AP.
The management of oil produced water (PW) constitutes a major challenge to oil companies. The options usually adopted for PW are disposal, injection and reuse. In all cases, a PW treatment is required in order to avoid damages to the environment and to production facilities or to allow its reuse without causing damage to processes in which the PW is used. The membrane separation processes (MSP) has been shown to be capable of treating effluent with high content of emulsified oil and with medium and small sizes particle, competing well with more complex treatment technologies such as flotation. The aim of this paper was to present a review of the PW treatment by MSP, discussing the main aspects of the PW and the conceptual aspects of the MSP, with emphasis on their application for removal of oil from the PW.