MICROBIAL ACTIVITIES OF THE SUBSTRATE IN THE INTEGRATED VERTICAL-FLOW CONSTRUCTED WETLANDS TREATED WITH PHTHALATE ACID ESTERS

In this paper, a new-typed constructed wetland(IVCWs) consisting of downflow-upflow is described. Substrates were sampled using a column sampler in subsurface (7—8cm). The amounts of bacteria, actinomyces and fungi were determined using serial dilution plate method; substrate enzymatic activities, such as dehydrogenase, urease, phosphatase were measured by colorimetry; soil respirations were determined using alkali absorption method. This research was done after the source water of IVCWs had been treated continuously with Phthalate Acid Esters for more than one year. The results showed that the microbial activities in the down-flow of both the control systems and to treated systems were obviously stronger than those in the up-flow. As the effects of phthalate acid eaters on microorganism activities were concerned, the enzymatic activities and respirations in the treated systems were stronger than the control systems, and which in the former system were 2.0—6.9 times of that in the latter. The total microbial amounts showed no obvious difference between two systems, but the community structure existed variation, especially, the fungal amounts in the treated systems were 4.6—5.5 times of which in the control systems, amount to 105cfu/g; Adding different phthalate acid eaters to two treated systems, the results showed that there was no obvious difference between treated systems added to different long-chain (DOP) and short-chain (DBP) Phthalate Acid Esters after the systems had been running for one year, which were different from the results of incipience, and incipient results showed that the microorganism activities of treated system added with DBP were higher than that added with DOP. The research results of wetland biofilm showed that the mass of biofilm were 1—6mg/g, the enzymatic activities of biofilm amounted to 70% of the total medium enzymatic activities, the activities of dehydrogenase were even 10 times of that of the medium, which showed that biofilm was the main component of the wetland microorganisms and contributed more to the microorganism activities. All of the parameters such as microorganism quantities, enzymatic activities and soil respirations in downflow chamber are stronger than that in upflow. The substrate in downflow is 10cm higher than that in upflow, then the substrate surface in upflow is prone to being submerged, and oxygen content there is lower; dissolved wastewater first passes through downflow, then through upflow and nutrient contents in upflow chamber is also lower than that in downflow chamber. The difference of oxygen and nutrient contents can directly influence microorganism population size. Enzymatic activities, respiration, and microorganism quantities show consistency to some degree, which shows relativity exists among them. As microorganism quantity is concerned, there is little difference between treated systems (added PAEs for more than one year) and control systems. Results show that Fungi amount in treated system is higher than that in control system. We also compare long-chain PAEs(DOP) with short-chain PAEs(DBP), despite of the difference of water-solubility and degradation, results show that there are little difference, which is different from former research results (added PAEs for only one month). The reason is that in early days, short-chain PAEs is “popular”with indigenous microorganism and it can be taken as one carbon source, so former research results showed that microorganism quantities in system treated with DBP is higher than that treated with DOP, but when systems work well for more than one year, microorganisms in substrate adapt to environment, so the quantities difference is unconspicuous.