生物除铁除锰滤层营养条件的研究

采用模拟生物除铁除锰滤柱,通过测定整个生物滤层对铁、锰的去除效果考察了营养物质对生物滤层综合生化能力的影响,从而探求了生物滤层对铁、碳、氮等营养元素的需求.结果表明,成熟滤层内的铁、锰氧化细菌对进水铁的营养需求极低(0.04 mg/L).成熟滤层对有机物具有一定的去除能力,而无机碳减少量相对较大,大约有3～4 mg/L,溶解在水中的二氧化碳即可保证滤层对碳的需求.成熟滤层将氨氮转化为硝酸盐和亚硝酸盐,但这种转化实际上并没有使水中氮的总量减少,只是氮的形态发生了转化;而滤柱内氮的减少是被生物体利用的结果.极低的氮素含量即可保证成熟生物滤层对氮素的需求.这表明极低的营养条件即可满足铁、锰氧化细菌的正常生理代谢,铁、锰氧化细菌可以在贫营养环境下生存.结合全国大部分地区的地下水水质状况,进而得出地下水生物除铁除锰技术在全国大部分地区可以推广使用.

Study on the nutrient condition of the filtering layer for biological removal of iron and manganese

This paper aims at introducing our study on the needs of biological filtering layer for iron, carbon, nitrogen and other elements, when modeling biological removal of iron and manganese from the groundwater. Our experimental research is done through laboratory simulation of filtering columns while stressing the study of the nutritional conditions of the total biological system. As is known, nutrient or nutrition is the material basis for the microorganisms to get multiplied as bacteria in the filtering layer. For this purpose, the paper has investigated the effect of the nutrient on the composite biological oxidation capacity of the filtering layer through measuring its total removal effect on the iron and manganese. The results of our experiments show that at the mature stage, the need of Fe~ 2+ is actually minute in amount, to be exact, 0.04 mg/L Fe~ 2+ would be enough for the iron and manganese oxidized bacteria to keep their normal metabolism. Most part of the organic substance in the raw water is removed through the mature filtering layer. On the contrary, greater amount of inorganic carbon is reduced at this stage, that is, about 3-4 mg/L through the whole mature stage. At the same time, there may exist enough carbon dioxide for the filtering layer to be dissolved in the water. Though ammonia in the raw water is changed into nitrate and nitrite through the filtering layer, it changes only the form of nitrogen. Therefore, our research proves that it is rather easy to satisfy the normal metabolism of the iron and manganese oxidized bacteria under the low nutritional conditions. Thus, it can be concluded that the biological removal of iron and manganese from groundwater can be made available for the general underground water purification for most areas of our country.