Desalinization of Soy Sauce Waste by an Upward Flow of Water through the Column

The present study examines a method of improving the desalinization efficiency of the column-type desalinization process for soy sauce waste by feeding the water upward through the column. Four small-diameter perforated water-feeding pipes were inserted through the bottom of the desalinization column. Water was fed through these pipes into the pulverized soy sauce waste layer in the column producing a suspension. This allowed the salt in the soy sauce waste to be eluted into the water and ultimately discharged. The water was then fed again from the top of the column to wash out the remaining salt in the soy sauce waste. The proposed desalinization process addresses the problem of compressed soy sauce waste at the bottom of the column that affects the conventional column process and thus improves the stable desalinization efficiency not only for soy sauce waste produced from powdered raw materials but also for soy sauce waste produced up to five days. The efficiency of the proposed desalinization treatment is two and a half times higher than that of our previously reported process.