4种禾草用于覆盖层灌溉垃圾渗滤液的比较

COMPARISON OF FOUR GRASSES USED AS COVER FOR IRRIGATION TREATMENT OF LANDFILL LEACHATE

以改良型百慕大草、普通狗牙根、香根草、百喜草4种禾草和经循环回灌处理后的渗滤液为实验材料,进行了不同体积浓度渗滤液在模拟垃圾填埋场植被覆盖层灌溉处理的实验研究.结果表明,经一个生长季12 mm d-1的渗滤液灌溉胁迫,改良型百慕大、香根草、普通狗牙根皆能生长,而百喜草在高浓度下不能存活.渗滤液15%浓度时,4种禾草生物量最大,随浓度的增大生物量明显下降,生物量和渗滤液体积浓度呈显著负相关;生物量下降率的大小表明了禾草对渗滤液的抗性:百慕大＞香根草＞狗牙根＞百喜草.高浓度渗滤液灌溉会导致禾草活性氧产生和抗氧化系统清除间动态平衡的破坏和膜脂过氧化的加剧,加速了禾草衰老进程;保持抗氧化酶活性的稳定是禾草抗渗滤液胁迫的机制之一.渗滤液灌溉裸土覆盖层处理水量削减率和COD去除率分别为52.5%～57.6%和64.3%～66.1%,植被覆盖层灌溉处理效果优于裸土,水量削减率为61.3%～91.2%,COD去除率66.4%～94.0%.低浓度渗滤液下百慕大、狗牙根水量削减和COD去除效果较好,而高浓度时香根草较好.渗滤液覆盖层灌溉处理的水量削减和COD去除效果表明,填埋场终场覆盖层灌溉处理渗滤液是可行的,改良型百慕大和香根草是适宜的植被材料.

Recirculated landfill leachate was irrigated into mimic landfill vegetation to analyze the effect of different volume concentrations and different grasses on leachate treatment efficiency. Four grasses were selected： improved bermudagrass Dol sol （ Cynodon dactylon cv. Dol sol）, common hulled bermudagrass [ Cynodon dactyoln （ L. ） Pers], vetiver grass （ Vetiveria zizanioides Nash） and bahia grass （Paspalum notatum Flugge）. The results showed that all the grasses could survive with the irrigation loading of 12 mm/d for one growth season, except that bahia grass died with high volume concentration. Most aboveground biomass was obtained when irrigated with 15% volume concentration. Once the concentration surpassed 15% and increased gradually, vegetation biomass decreased, negatively related to volume concentration. The decreasing rate of biomass indicated that the resistant ability to leachate was： bermudagrass 〉 vetiver grass 〉 common bermudagrass 〉 bahia grass. High volume concentration leachate resulted in the imbalance of activated oxygen production and scavenge, accelerated the process of lipid peroxidation and imposed on the grasses detrimentally. Leachate volume reduction of 61.3% -91.2% and COD removal＇ of 66.4% - 94.0% were obtained respectively by irrigated leachate into grass cover, while only 52.5% - 57.6% and 64.3% 66. 1% into bare cover. Under low volume concentration of leachate irrigation, the volume and COD reduction efficiency of bermudagrass was better than those of vetiver grass, while vetiver grass better than bermudagrass under high volume concentration of leachate irrigation. The good efficiency of leachate volume reduction and COD removal meant that leachate treatment through irrigation on landfill vegetation was feasible, and bermudagrass and vetiver grass were suitable vegetationr. Fig 4, Tab 1, Ref 19