Research On The Preparation Of Ecological Concrete Used In Marine Environment And Its Ecological Efficiency

Marine water eutrophication has brought great loss to people’s lifeand production, the voice for prevention and control of marine watereutrophication has been growing day by day. The present measures of the marinewater eutrophication are mainly used to control pollution emissions; measures formarine water purification are rare. At present, the ecological concrete used inembankment slope protection provides a good way for the purification of marinewater. Using ecological concrete to construct artificial shores and placing largeecological concrete blocks into the ocean as fish reefs, under the premise of meetingbasic functional requirements, the porous structure of ecological concrete canprovide the adherence and growth space for creatures, animals and plants in the sea,which can promote the remediation of the marine ecosystem, so as toachieve the purification for the marine water quality to some extent.This paper mainly studies three aspects: molding technologies of ecologicalconcrete, the marine ecological security of ecological concrete, and the biologicaladherence of ecological concrete and the effect of marine waterpurification. Conclusions are as follows:⑴Under the premise of meeting basic performances of the strength, frostresistance and sulfate resistance of ecological concrete, we have made ecologicalconcrete blocks and measured their porosity respectively with preparative techniquesof coarse aggregate close packing filling theory and coarse aggregatepackage thickness filling theory, and found that the preparative technique of coarseaggregate package thickness filling theory can control the porosity of concrete blocksbetter and successfully prepared concretes respectively with porosities of15%,20%and25%.⑵The ecological concretes with different porosities have similar influence onthe pH of seawater. With the increase of the porosity, the influence of ecologicalconcrete on the pH of seawater will increase. The ecological concrete block withporosity of25%has greatest effect on the pH of seawater, which increase from about8.06to8.55, however, it just has little effect on the experimental water⑶The ecological concrete has a good adhesion in natural waters, after a monthbeing placed into natural waters, due to its big specific surface area, the ecological concrete with big porosity has a obviously greater biomass attached thanthat with small porosity.⑷This paper has adopted experimental water with COD concentration of30mg/L, total nitrogen concentration of6mg/L, saturated dissolved oxygen and watertemperature of25℃to conduct natural membrane forming for70days, theremoval efficiency of the concrete block is0.8～0.9mg/cm~2·h; the removalefficiency of ammonia nitrogen is0.078～0.18mg/cm~2·h; the accumulation ofnitrogen oxide is0.006～0.054mg/cm~2·h; the accumulation of nitrate nitrogen is0.039～0.117mg/cm~2·h and the total nitrogen removal efficiency is0.024～0.09mg/cm~2·h. Compared to the ammonia nitrogen removal efficiency, total nitrogenremoval efficiency is not high, but the ecological concrete changes most ammonianitrogen into nitrate nitrogen, which is conducive to the survival of creatures in thesea.⑸We select ammonia nitrogen with concentration of0.1mg/L,0.5mg/L,1.0mg/L and1.5mg/L respectively and COD/AN ratio of5,10,15,20and25respectively. In the same nitrogen concentration, with the increase of COD/ANratio, the ammonia nitrogen removal efficiency of ecological concrete firstly increasesand then decreases, COD/AN ratio reaches the maximum value at15hours. Usingdata processing software SPSS to process the data, we have discovered there arebinomial characteristics and good fitting degree between the ammonia nitrogenremoval efficiency of ecological concrete and COD/AN ratio, thus we obtains thequadratic mathematical model between the ammonia nitrogen removal efficiency ofecological concrete with different porosities under different ammonia nitrogenconcentrations and COD/AN ratio, and through this mathematical model, we canderive the ammonia nitrogen removal efficiency of ecological concrete with differentporosities in different water qualities.This paper has conducted research on the ecological concrete used inthe marine environment, also provided the basis for water purification effects ofecological concrete in different waters and laid a good theoretical foundation forthe following researches; it has a certain reference value.