Concurrent Purification of Organic Pollution and Nutrients in Kitchen Wastewater with Thin Layers of Soil (Thin Carrier)

• Published in: Journal of Japan Society on Water Environment Vol. 28; no. 5; pp. 347 - 352
• Main Authors: KIJI, Masato, SUETSUGU, Aya
• Format: Journal Article
• Language: Japanese
• Published: Japan Society on Water Environment 10.05.2005
• Subjects: concurrent purification of organic pollution and nutrients; economical and compact technique; gray water; nitrogen and phosphorus; water purification by soil
• ISSN: 0916-8958; 1881-3690
• DOI: 10.2965/jswe.28.347

We developed a method of effectively purifying untreated graywater by the self-purification of surface soil. In this method, polluted water is purified by infiltrating and running it in a carrier of a thin container. The top of the container is open, and the base is sloped. We called this method “Keisya-Dosou-Hou”, meaning sloped layers of soil. We performed an experiment to purify kitchen wastewater using this method. The experiment was carried out for two years and six months without changing or supplying in the carrier. The average volume of treated water was 90l·d-1, and 70l·m-2·d-1 per soil area. The average removal rates in percentage were as follows : SS: 86%, BOD: 82%, COD: 85%, T-N: 78% and T-P: 86%. The average removed weight per soil area were as follows : SS: 8.6g·m-2·d-1, BOD: 45.9g·m-2·d-1, COD: 24.6g·m-2·d-1, T-N: 1.72g·m-2·d-1, T-P: 0.338g·m-2·d-1. The results show that it is possible to purify organic pollution and nutrients concomitantly. It was considered that T-N was removed concurrently due to progress of nitrification and denitrification in both layers of the structure. When wastewater containing much organic pollution was treated with a thin layer of soil, the upper part of the container became aerobic by bordering with atmosphere, and the bottom part became anaerobic by decomposing organic pollution. The results of this experiment show that “Keisya-Dosou-Hou” is an economical and compact technique of purifying graywater. Also the result made clear the accuracy of the self-purification of surface soil, and it was considered that the results had paved ways for the construction of new water purification system.