Anaerobic treatment method and anaerobic treatment apparatus

An anaerobic treatment apparatus comprising:

• a reaction tank which retains a granular sludge;
• and
• a nitric acid/nitrous acid addition means which is connected to the reaction tank and which adds nitric acid, nitrate salt, nitrous acid or nitrite salt so that a tank liquid within the reaction tank contains nitric acid or nitrous acid.

A method of anaerobic treatment comprising:

• introducing a liquid to be treated to a reaction tank which retains a granular sludge;
• and
• contacting the liquid to be treated with the granular sludge while adding one or more substances from a group consisting of nitric acid, nitrate salt, nitrous acid, nitrite salt and glucide to the reaction tank or the liquid to be treated.

A method of anaerobic treatment including introducing a liquid to be treated to a reaction tank which retains a granular sludge comprising:

• adding glucide to the reaction tank or the liquid to be treated and contacting the liquid to be treated with the granular sludge in the case where the amount of organic matter which have a carbon number of four or less contained in the liquid to be treated are 70% by mass or more of the total contained organic matter, or in the case where the liquid to be treated contains one or more agents chosen from a group consisting of a chelating agent, a scale dispersant, and a bactericidal agent, or in the case where the sludge load introduced to the reaction tank exceeds 0.3 KgCODcr/kg-vss/d or a upflow velocity within the reaction tank exceeds 1 m/h.