Urine is rich in nutrients and can be applied as a fertilizer. The limitation on the application is the transportation cost for the farmlands. The cost estimation required 80% of the volume reduction for a feasible utilization of urine in the farmlands near urban areas. The volume reduction system by forward osmosis (FO) process was proposed to address this problem. In this study, the experiments on FO process with real and synthetic hydrolysed urine were performed to assess the FO performances, to evaluate the solute diffusion and to describe the water flux considering the activity of solutes. This study showed both real and synthetic urine can be concentrated to 2–5 times with 2–5 mol/L sodium chloride solution. High diffusivity of ammonia and carbonates were observed, but the diffusion of other solutes was low. The activities of the solutes in the non-ideal solution should be considered for estimation of the osmotic pressure of the solution which reflects the water flux. The software PHREEQC can be used for estimation of the activities in such high concentration solutions. The organic matter in real hydrolysed urine had a negligible effect on the osmotic pressure variations.
This study aims to show the stability of diazepam, a member of the benzodiazepines and psychoactive drug, in the environment. Two experiments were carried out: biological degradation by using activated sludge and advanced oxidation processes (AOPs). AOPs process was proposed and applied. TiO2, used as catalyst, has two important properties: high photo-catalytic activity and low cost. Photodegradation of diazepam was much faster under light irradiation in the presence of TiO2 (half-life = 6 hours) than under Suntest irradiation (half-life = 34 hours). Considering that the photo-catalytic process started after the biological treatment on the water body containing a very little amount of contaminants, the removal of this pharmaceutical compound was quite complete and the degradation products were detected below the legal limit.
Reduction of seaweed beds is a serious problem in coastal areas of Japan and worldwide, and the lack of dissolved iron in seawater may contribute to the destruction of this ecologically important habitat. We have previously developed a method for restoring seaweed beds using a mixture of steelmaking slag and composts containing humic substances. Since October 2004, we have been performing field tests on the Shaguma coast in Mashike-cho, Hokkaido, Japan, to confirm the effectiveness of this method. However, thus far, no studies have been conducted to evaluate the effects of the hydrodynamic conditions by calculating the iron distributions in the area of the field tests. In this study, we evaluated the continuous effects of this iron fertilization method in Mashike by comparing the changes in seaweed bed distributions with the analyzed iron concentrations over a 5-year study period and the simulation results of iron distribution in the study area. Our findings demonstrated that the biomass of seaweeds at the fertilized (experimental) site was larger than that at the reference site. We also found that both the analyzed iron concentration and the calculated iron distribution in the area corresponded to the distribution of seaweed beds.
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