Environmental Sanitation Engineering ›› 2023, Vol. 31 ›› Issue (3): 1-8.doi: 10.19841/j.cnki.hjwsgc.2023.03.001

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Study on Alkaline Stabilization of Source-separated Urine in Alpine-cold and Water Shortage Area of China

DUAN Wenjun, LU Yin, SUN Lili, LU Jun, LI Jiyun, XU Kangning   

  1. 1. Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University; 2. Beijing Guohuan Tsinghua Environmental Engineering Design & Research Institute Co. Ltd.; 3. School of Environment, Tsinghua University
  • Online:2023-07-03 Published:2023-07-03

Abstract: The soil of landfill liners was derived mainly from nearby area. There was a close correlation between the antipollution capacity of liners and soil permeability. The standard consolidation experiment was carried out on the sieved soil with six particle size ranges at different depths near the typical red-layer landfill in Sichuan Province, so as to study the fundamental physical parameters and the trend of changes in saturated density and permeability coefficient. According to the experimental results, the saturated density of red-layer sieved soil(ρsat) ranged from 0.13 to 0.25 g/cm3 at the early consolidation stage (P≤800 kPa), and it was from 0.11 to 0.18 g/cm3 at the later stage (800 kPa<P<3 200 kPa), both showed a trend of logarithmical increase. Besides, there was a significant linear negative correlation between the ρsat and the void ratio e (r>0.99). The consolidation of sieved soil in the red layer was mainly concentrated in the vertical pressure range from 12.5 to 800 kPa. When the vertical pressure exceeded 800 kPa, the sieved silty clay in the red layer was applicable as the soil-protecting layer in the impervious system of landfill. Meanwhile, based on the existed seepage model(lgkv-lge), two t

Key words: latrine pit, source separation, urine, stabilization, ammonia loss

Urine source separated latrine pit is very suitable for the reconstruction of toilets in the rural areas in alpine-cold and water shortage area in China. However, urea hydrolysis in source-separated urine resulted in nitrogen loss due to ammonia volatilization and odor problems in the processes of collection and long-term storage of urine. Therefore, with the aim of using urine as liquid fertilizer, the alkaline stabilization of source-separated urine in alpine-cold and water shortage area of China was investigated. The results showed that it was easier to inhibit urea hydrolysis and stabilize urine in long-term storage at higher pH and lower temperature. At the same time, higher pH was necessary to inhibit urea hydrolysis when urea hydrolysis activity was higher. Compared with plant ash, Ca(OH)2 and CaO were more suitable for long-term stabilization of urine. When the dosage of Ca(OH)2 was 5.2 g/L, the pH of urine was adjusted to 11.0, which could effectively stabilized urine at 180 days. Compared with hydrolyzed urine, the application of stabilized urine had a lower risk of soil salinization and alkalization when the fertilizing amount of urine was lower than 1.5 L/m2.
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