Abstract: A wastewater treatment apparatus comprises a nitrogen-containing dye containing wastewater inlet connected to an obligatory anaerobic tank to bring wastewater containing a nitrogen-containing dye into contact with sulfate-reducing bacteria under obligatory anaerobic conditions, a nitrification tank to bring the wastewater into contact with nitrifying bacteria under aerobic conditions, and a denitrification tank to bring the wastewater into contact with the denitrifying bacteria under anaerobic conditions.

Abstract: To provide a wastewater treatment apparatus capable of easily decolorizing and decomposing, at a low cost, a persistent nitrogen-containing dye such as azo compound in wastewater containing a nitrogen-containing dye, being compact, having excellent durability and high processing power and ensuring long-term stable operation. A wastewater treatment apparatus for decolorization and denitrification of wastewater containing a nitrogen-containing dye, which comprises an obligatory anaerobic tank for bringing the wastewater containing a nitrogen-containing dye into contact with sulfate-reducing bacteria under obligatory anaerobic conditions, a nitrification tank for bringing the wastewater into contact with nitrifying bacteria under aerobic conditions and a denitrification tank for bringing the wastewater into cost with the denitrifying bacteria under anaerobic conditions.

Abstract: To provide a wastewater treatment apparatus capable of easily decolorizing and decomposing, at a low cost, a persistent nitrogen-containing dye such as azo compound in wastewater containing a nitrogen-containing dye, being compact, having excellent durability and high processing power and ensuring long-term stable operation.

Abstract: Provided are an apparatus and a method for waste water treatment not generating excessive sludge, for which down-sized tanks are usable. The apparatus comprises an aeration tank where waste water to be treated is kept in contact with carrier particles in an aerobic condition, and a complete oxidation tank. In this, the liquid in the complete oxidation tank is filtered through a separation membrane and the resulting filtrate is discharged out of the system. The s-BOD sludge load to the complete oxidation tank is preferably at most 0.1 kg-BOD/kg-MLSS·day.

Abstract: A waste water treatment apparatus which is compact, and excellent in durability, has a high treatment performance and can stably operate for a long time is provided. In a waste water treatment apparatus at least comprising a waste water treatment tank in which a carrier particle immobilizing a microbe is charged and decomposing and eliminating an organic matter and/or an inorganic matter contained in a waste water, and a membrane module for filtrating a water to be treated which flows out from said treatment tank, a non-permeating water not passing thorough the membrane module is returned and circulated to said treatment tank. In a waste water treatment apparatus at least comprising a waste water treatment tank in which a carrier particle immobilizing a microbe is charged and decomposing and eliminating an organic matter and/or an inorganic matter contained in a waste water, a carrier immobilizing a microbe is an acetalized polyvinyl alcohol hydrogel.