| Eutrophication of lakes and reservoirs is one of the urgent problems to be solved and gained more and more researchers' attention.Eutrophication is in fact a kind of environmental pollution caused by the excessive reproduction of algae.Algae depends on a number of elements,among which phosphorus is regarded as the key factor.EPRC is a kind of particles which can remove phosphorus efficient researched and developed by our team.The results show that it has a good effect on the removal of phosphorus from wastewater.Ecological techniques is an important method of controlling water eutrophication,of which ecological floating bed is one of the most representative ones and has been wildly used in the treatment of polluted lakes and rivers.Previous studies mostly focus on the ecological floating island for removal of high concentration of pollutants in water,but pay little attention to the source water with low pollutant concentration.And the removal effect is limited because of the limitation of plant absorption efficiency.Based on this background,this experiment adopts the EPRC with high phosphorous removal efficiency material developed as the base of ecological floating island,in order to enrich the low-concentration phosphorous to be further used by plants,thus enhancing the phosphorous removing ability.This study mainly includes:verification of phosphorus removal effect of EPRC;research on floating bed for nitrogen and phosphorus removal and hydroponic growth ability of Water spinach;research on EPRC composite floating bed for phosphorus and nitrogen removal.First of all,the phosphorus removal characteristics of EPRC were studied.The adsorption of EPRC on phosphorus accords with the classical Langmuir equation and it was shown that the adsorption of phosphorus could be better described by pseudo second-order equation.The appropriate added amount and adsorption time was determined,which are 2g/L,and the adsorption effect was significant in the first 24 hours after the addition of EPRC.Secondly,removal of phosphorous and nitrogen in the lower concentration of nutrients by different number of Water spinach(2,4,6,8)was compared to determine an appropriate number,and 6 per 10L is the optimum number.At the end of the experiment,the plant roots and stems increased 2.2 and 1.3 times respectively explained that water spinach can be used as a floating bed plant.Finally,EPRC was combined with the Water spinach to study the removal of phosphate and nitrogen under low concentration conditions and make comparison with particle floating bed and plant floating bed.The results showed that,under different initial phosphorus concentration,the order of PO43-and TP removal ability was composite floating island>particle floating bed>plant floating bed.The removal rate of ammonia nitrogen of particle floating bed was only 7.25%,and composite floating bed was better than plant floating bed,the rates were 80.9%and 76.2%.The composite floating bed and plant floating bed were the same as the total nitrogen removal rate,they were 76.8%?76.0%.The roots and stems of the plants in composite floating bed increased 1.90 and 1.54 times respectively,meantime,plants in plant floating bed increased 1.25 and 1.21 times respectively at the end of the experiment(under the condition of initial phosphorus concentration was 0.8mg/L).Composite floating bed makes the water pH value increased from 7.8 to 8,while the particle floating bed increased to 8.5.According to the research,a new type of floating bed was designed,which EPRC was used as a plant growth substrate and simultaneous phosphorus removal.Meanwhile,elastic packing was added to this kind of bed and introduced floating plants cooperating with plant on bed for purifying water quality.The purpose of this design is to provide reference for engineering applications. |
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