Fdz-Polanco F, Fdz-Polanco M, Fernández N, Garciá P A, Villaverde S
Department of Chemical Engineering, Valladolid University, Spain.
Water Sci Technol. 2001;44(8):77-84.
The biochemical processes involved in the anaerobic degradation of carbon, nitrogen and sulfur compounds can be represented by an oxidation-reduction or electron donor-acceptor scheme. The theoretic values of Gibbs free energy (deltaG0) calculated from thermodynamic data indicate the feasibility of the reactions. The interactions C-S and C-N are well known but there is a lack of information about the interaction N-S. The anaerobic transformation of nitrates using reduced sulfur compounds can be explained considering that nitrate acts as electron acceptor while reduced sulfur compounds are the electron donors. A new N-S interaction in anaerobic conditions (ORP = -425 mV) has been experimentally observed when treating industrial wastewater rich in organic nitrogen and sulfate. The mass balances of the different nitrogenous and sulfur compounds in the liquid and gas phases clearly indicated an uncommon evolution. An important percentage of the nitrogen entering the reactor as TKN was removed from the liquid phase appearing as N2 in the gas phase. Simultaneously, only part of the sulfate initially present in the influent appeared as sulfide in the effluent or as hydrogen sulfide in the gas. These experimental observations may suggest a new anaerobic N-S biological interaction involving simultaneous anaerobic ammonium oxidation and sulfate reduction, ammonium being the electron donor and sulfate the electron acceptor.
碳、氮和硫化合物厌氧降解过程中涉及的生化过程可用氧化还原或电子供体-受体模式表示。根据热力学数据计算出的吉布斯自由能（ΔG0）理论值表明了这些反应的可行性。碳-硫和碳-氮相互作用广为人知，但关于氮-硫相互作用的信息却很匮乏。利用还原态硫化合物对硝酸盐进行厌氧转化可解释为硝酸盐作为电子受体，而还原态硫化合物作为电子供体。在处理富含有机氮和硫酸盐的工业废水时，实验观察到了厌氧条件下（氧化还原电位=-425 mV）一种新的氮-硫相互作用。液相和气相中不同含氮和含硫化合物的质量平衡清楚地表明了一种不寻常的演变。以总凯氏氮形式进入反应器的氮中有很大一部分从液相中去除，以氮气形式出现在气相中。同时，进水最初存在的硫酸盐只有一部分以硫化物形式出现在出水或以硫化氢形式出现在气相中。这些实验观察结果可能表明存在一种新的厌氧氮-硫生物相互作用，涉及同步厌氧氨氧化和硫酸盐还原，氨作为电子供体，硫酸盐作为电子受体。
