Factors Affecting Linear Alkylbenzene Sulfonates Removal in Subsurface Flow Constructed Wetlands

The behavior of linear alkylbenzene sulfonate (LAS) and
sulfophenyl carboxylate (SPC) biointermediates in a pilot
subsurface flow constructed wetland (SFCW) is reported for
the first time. The effects of wetland configuration and
operation on their treatment efficiency were investigated.
The pilot SFCW constituted by eight beds of 55 m2 with
different aspect ratios (1 × 1; 1.5 × 1; 2 × 1; 2.5 × 1), two
water depths (i.e., 0.47 and 0.27 cm) at 5 cm below
surface and two medium sizes (i.e., D60 = 10 mm and 3.5
mm) planted with Phragmites sp. That SFCW pilot treats urban
wastewater (i.e., 200 inhabitants) and was operated at
four hydraulic loading rates (HLRs) (20, 27, 36, and 45 mm
d-1). Influent and effluent sampling was carried out
from May 2001 to January 2002 with a weekly pattern.
Main results were as follows: (i) water depth has a major
influence on the performance of SFCW for the LAS
removal, and HLR shows significant effect on SPC evolution;
(ii) water temperature has a significant effect on the
LAS evolution; (iii) biodegradation of LAS and SPC can
occur under sulfate-reducing environment and mixed
conditions (i.e., sulfate-reducing and denitrification), but
aerobic respiration cannot be excluded; and (iv) C13 LAS
homologues were generally removed in higher extent than
the shorter alkyl chain counterparts. In the most appropriate
conditions, LAS and SPC can be biodegraded up to
71% and 11%, respectively, in the pilot SFCW evaluated.

本研究首次报道了直链烷基苯磺酸盐（linear alkylbenzene sulfonate, LAS）与磺苯基羧酸盐（sulfophenyl carboxylate, SPC）两种生物中间体在中试规模地下流人工湿地（subsurface flow constructed wetland, SFCW）中的环境行为，并探讨了湿地构型与运行参数对其污染物去除效果的影响。该中试SFCW由8座单座面积为55 m²的床体组成，各床体设置不同长宽比（1×1、1.5×1、2×1、2.5×1），并采用2种水深（距床体表面5 cm处分别为0.47 cm与0.27 cm）、2种填料粒径（D60分别为10 mm与3.5 mm），床体中种植芦苇属（Phragmites sp.）植物。该中试SFCW用于处理服务200名居民的城市污水，运行期间设置4种水力负荷率（hydraulic loading rates, HLRs）：20、27、36、45 mm·d⁻¹。采样工作于2001年5月至2002年1月间开展，采样频率为每周1次。主要研究结果如下：(i) 水深对SFCW去除LAS的处理性能具有显著影响，而HLRs则对SPC的降解过程存在显著作用；(ii) 水温对LAS的降解过程具有显著影响；(iii) LAS与SPC均可在硫酸盐还原环境及混合代谢环境（即硫酸盐还原与反硝化共存环境）中发生生物降解，但有氧呼吸途径亦不可排除；(iv) C13取代的LAS同系物通常较短烷基链同系物具有更高的去除率。在本研究所评估的最优工况下，该中试SFCW对LAS与SPC的生物降解率分别可达71%与11%。