The Method of Improving the Corrosive Environment in a Reclaimed-Water Pipe using the SA Method
To increase the practical-use value of multi-water-resources, reclaimed water was used as the experimental water because the frequency of reclaimed-water usage has been very high of late. The SA method was then applied to a reclaimed-water pipe as a way of inhibiting its corrosion, and its anticorrosion effect was observed. Corrosion effect by the sacrificial anode method was measured by lab scale experiments, reclaimed water was used as the experimental water, and also tap water was used as a control group. As a result of experiments, efficiency of SA method can be made higher by increasing the amount of SA metal. In addition, anticorrosive effect was not large compared to the reclaimed water condition, and it was determined that efficiency of the SA method increases in a pipeline where high-conductivity water flows. And the corrosive-index (KRWI) trend was not large regardless of the flow time and the degree of corrosion.
Characteristics of Corrosion and Water Quality in Simulated Reclaimed Water Distribution Pipelines
Water reuse has been highlighted as a representative alternative to solve the lacking water resource. This study carried out a study on the pipe corrosion and water quality change which can occur through the supply of reclaimed water, using a simulated reclaimed water distribution pipeline. Galvanized steel pipe (GSP), cast iron pipe (CIP), stainless steel pipe (STSP) and PVC pipe (PVCP) were used for the pipe materials. Reclaimed water(RW) and tap water(TW) were respectively supplied into simulated reclaimed water distribution pipelines. As a result of performing a loop test to supply reclaimed water to simulated reclaimed water distribution pipelines, the weight reduction of pipe coupons showed the sequence of CIP > GSP > STSP ≈ PVCP. In addition, reclaimed water showed a high corrosion rate comparing to that of tap water. In case of CIP, the initial corrosion rate showed 3.511 mdd(milligrams per square decimeter per day) for reclaimed water and 2.064 mdd for tap water and the corrosion rate for 90 days showed 0.833 mdd for reclaimed water and 0.294 mdd for tap water. Also in case of GSP, the initial corrosion rate showed 2.703 mdd for reclaimed water and 2.499 mdd for tap water and the corrosion rate for 90 days showed 0.349 mdd for reclaimed water and 0.248 mdd for tap water, which was a tendency similar to that appeared in CIP with a tendency to reduce the corrosion rate. As a result of water quality changes of reclaimed water at pipe materials to carry out the loop test, there was higher conversion ratio of ammonia into nitrate in CIP and GSP with higher corrosion rate than that in STSP and PVCP where no corrosion has occurred. The highest denitrification rate of nitrate could be observed from CIP with the most particles generated from corrosion. In CIP, it could be confirmed that there was MIC (Microbiologically Induced Corrosion) as a result of EDS (Energy Dispersive X-ray spectrometer System) analysis results.
방목초지에서 우분 퇴비 시용이 목초생산 및 토양에 미치는 영향
This study was conducted from 2003 to 2005 at crop field of National Institute of Subtropical Agriculture, RDA, in Jeju. The treatment consisted of chemical fertilizer 100%(CF 100%, T1), cattle manure 100%(CM 100%, T2), CF 50%+CM 50%(T3), CF 25%+CM 75%(T4), CM 100%(1st yr.)+CF 100%(2nd yr,)+CM(3rd yr)(T5), CM 100%(1st yr.)+CF 100%(2nd yr.)+CF(3rd yr.)(T6). The highest substitution effect of chemical fertilizer for cattle manure indicated that the highest yield(Avg. 11,169 kg/ha) obtained from CM 100%(1 yr.)+CF 100%(2 yr.) treatment. The forage yield of CM 100%(1 yr.)+CF 100%(2 yr.) was 4% more than CM 100% application whereas was 3% less than CF 100% application. Changes of physical and chemical properties of soils for applications of CF 100% and CM 100% was clearly in cattle manure application. Especially, cattle manure application in pasture were superior to chemical fertilizer application with respect to organic matter(OM, %), total nitrogen(T-N, %), and avaliable phosphorous(P₂O?, %) contents of soils. In this present study, cattle manure application recorded slightly lower forage yields than CF 100% application but the combined use of cattle manure and chemical fertilizer was attribute to reduction of chemical fertilizer application rate as well as maintaining soil health on long-term basis.