Japanese Patent No. 4818474
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The Japanese Patent Office approved a new patent of the sludge reduction system utilizing the water hammering effects (Japanese Patent No. 4818474).
This invention features the method to treat sludge by the water hammer pressure to return the sludge that may occur due to the organic matter decomposition by microorganisms of the wastewater containing organic matter in the biological treatment tank to return to the biological treatment tank.
To return the sludge generated in the biological treatment tank by giving water hammer pressure, the final excess sludge reduces because organic matter is easily decomposed as
easily degradable intracellular material acting as bait of microorganisms.
This helps to reduce cost of the treatment of the excess sludge.
The facility cost can be greatly reduced than other method of treatment, and the
operation cost is also lowered.
|Sludge reduction method||None||Water hammer processing||cost reduction|
|A operating costs (Thousands of yen / day)||0||Ten|
|Reduction rate (%)||0||Fifty|
|Discharge sludge (tons / day)||Hundred||Fifty|
|B sludge disposal costs (Thousands of yen / day)||200||Hundred|
|Total processing costs (A + B) (ten thousand yen / day)||200||110||90|
Two Birds with One Stone: Power generation business utilizing the methane fermentation
We invented the method for the sludge reduction and power generation at the same time even with the existing methane fermentation tank without much investment.
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Features of power generation and sludge reduction business by digestive dehydration
promotion system using a steam ejector
- Very low cost solution as only the steam ejecting sludge concentration apparatus to be
added to the current system.
- Improving the digestibility as the small particle size SS in dehydration desorption
solution can be solubilized and re-digested with digestion tank.
- Resulting to reduce the sludge amount by lowering the sludge moisture content of the
existing dehydrator as the SS recovery rate of the dehydrator may be ignored.
- Low maintenance costs for equipment as no additional power required.
- High revenue may be expected as low equipment costs, low maintenance costs, high
demand of reducing industrial waste disposal as well as sales revenue of the power
Paper sludge reduction testing by water hammer processing
As a result of processing the paper sludge in water hammer device, the following findings were obtained. Water hammer pressure 16 Mpa, sludge in the water hammer number of times 18 times to solubilize more than 20% (V-SS standard).
After the aggregating the water hammer sludge was neutralized with charges of sludge surface with an inorganic flocculant, thereby improving the cohesive by a combination of cationic polymer flocculant.
When dewatering the flocculated sludge, dewatering efficiency is greatly improved by solid-liquid separation by simple concentrator (drum screen). When it is dehydrated by a filter press, the water content of the dehydrated cake is 25% which is a tremendous value. It is believed that the sludge cell wall was destroyed.
On a weight basis, the 80% reduction of the excess sludge was estimated as the result of the water hammer treated whole sludge back to the aeration tank as the decomposition of the SS is promoted.
Water hammered sludge characterized faster corruption period than normal sludge so that the sludge digestion period and digestibility can be expected to be greatly improved when it is applied before the process of anaerobic digestion (methane fermentation) .