针对低温期有机物去除率低的生物活性炭更换探究

Research on the Replacement of Biological Activated Carbon for Low Organic Matter Removal Rate during Low Temperature Period

江苏某水厂生物活性炭投运至今已达6年,出水水质指标能够稳定达到《生活饮用水卫生标准》(GB 5749—2006)的要求。但对照新实施的《江苏省城市自来水厂关键水质指标控制标准》(DB 32/T 3701—2019)要求,在其投产第三年的低温期即出现了COD_(Mn)不能稳定达标的问题,即生物活性炭寿命不足3年。研究显示主要是低温期炭上微生物活性较差且活性炭运行年限较长吸附能力不足所致。为保证出水水质,亟需进行活性炭更换。对活性炭更换方式的研究表明:新炭填充比例越高,对有机物的去除效果越好。但更换成本较高,且浪费了原有活性炭的吸附能力。中试研究表明,更换20%新炭的换炭方式能保证低温期出厂水COD_(Mn)值达到DB 32/T 3701—2019湖库水源不高于2.2 mg/L的要求,因此建议水厂于每年低温期到来之前(10月中旬)更换活性炭,更换比例为20%。与一次性全部更换相比,能够减少20%~40%的更换成本。

The biological activated carbon(BAC) of a water treatment plant in Jiangsu Province has been put into operation for 6 years, and the effluent quality can stably meet the requirements of the Standards for Drinking Water Quality(GB 5749-2006). However, according to the requirements of the newly implemented The Control Standards of the Key Water Quality Parameters for Urban Water Treatment Plants in Jiangsu Province(DB 32/T 3701-2019), in the low temperature period of the third year of BAC being put into use, COD_(Mn)can not reach the standard stably, that is, the life of biological activated carbon is less than 3 years. The analysis showed that it was mainly due to the poor microbial activity of BAC at low temperature period and the insufficient adsorption capacity of BAC with a long running life. In order to ensure the effluent quality, it is urgent to replace the BAC. The study on the replacement method of BAC showed that the higher the proportion of new BAC filling, the better the removal effect of organic matter. However, the replacement cost was high and the adsorption capacity of the original BAC was wasted. Pilot study showed that the carbon replacement method with 20% new BAC could ensure the COD_(Mn)of the effluent at low temperature period to meet the requirements of DB 32/T3701-2019, which required COD_(Mn)was not higher than 2.2 mg/L using the lake and reservoir as water source. Therefore, it is recommended that the water treatment plant replace the BAC before the low temperature period(mid-October) every year, and the replacement ratio is 20%. Compared with the one-time replacement, the replacement cost can be reduced by 20%-40%.