Development of a Water Purification Effect Using a Porous Concrete Sphere

【Author】

Sonoko Ichimaru;Yuki Yakai;Shota Minato;Yuma Kawasaki;Takahisa Okamoto;

【Abstract】

<正>The objective of this study is the development of a water purification system using porous concrete(PoC) spheres containing zeolite.First,an experiment was conducted in a test tank to investigate the water improvement with this treatment.The PoC specimens (30) were hung in a large water tank,and the total phosphorus(T-P) and total nitrogen (T-N) concentrations of the water from Lake Biwa were measured over seven weeks.The amount of T-P and T-N decreased dramatically during the first seven days.Thus,the water purification effect of the PoC spheres containing zeolite was confirmed.Second, the specific surface area of the voids was studied analytically.Thus,the number of PoC spheres necessary to treat a given amount of water was suggested according to the absorption amount of T-P and T-N measured in the test tank.Finally,the PoC spheres containing zeolite were applied to a pond at the Toji temple in Kyoto.The same experimental procedure as in the test tank was applied in this field test:however,the transparency of the water did not improve.The influence of water influx via rain and the consequent displacement of sludge to the water surface were considered the largest problems.If the influence of rain were not taken into consideration,the changes in the T-P and T-N concentrations would be expected to improve the water quality gradually. Originality The continuous voids of the PoCs make up 5-35%of their total volume(Okamoto et al, 1998);thus,small living creatures and plants can occupy the voids.Zeolite is an absorption material used for water improvement due to its ion exchange capacity.In this study,PoC and zeolite were combined to take advantage of these positive effects for water improvement purposes.In addition,the PoC was constructed in a spherical shape to increase the treatment efficiency.Zeolite was placed in the center of the PoC without mixing with a binder;otherwise,the zeolite would be covered and could not leverage the absorption effect.The water purification effect of this approach was investigated in a test tank and subsequently applied to a pond at the Toji temple to quantitatively evaluate its practicality and the performance in a natural environment.In addition,the specific surface area of the continuous voids of the PoC was discussed and estimated using image analysis.Therefore,the amounts of T-P and T-N absorbed per specific surface area of PoC were investigated.The number of PoC of a certain size necessary for water purification was also suggested.

【Keywords】

porous concrete;;porous concrete spheres;;water purification;;zeolite;;specific surface area of the voids

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