Method of treating wastewater using sequencing batch aerated lagoon

Abstract

A sequencing batch lagoon process is carried out in a minimum of two earthen lagoons and provides the treatment of municipal or industrial wastewater. Each lagoon is operated on fill-draw basis in a sequencing manner. Raw wastewater continues entering into one of the lagoons while the other lagoon is at full liquid level. The lagoon at the full liquid level will begin to discharge when the other lagoon at filling mode is reaching the full liquid level. The lagoon at the drawdown mode continues until the liquid level is down to the lowest liquid level. The wastewater feeding is then alternated to the lagoon which is at the lowest liquid level. The lagoon at the full liquid level shall have no contamination from raw wastewater or the lagoon at the filling mode. The biological reactions occur under aerobic and anoxic conditions. The aerobic conditions occur in the liquid or above the bottom sludge while the anoxic conditions occur near or within the bottom sludge. Air is provided by surface mechanical aerators or diffused aeration system. The aeration system is shut down during the discharge mode and is turned back on during the filling mode. Sludge in the lagoon is not wasted during the operation of sequencing batch lagoon process. The capacity of each lagoon depends on the number of lagoons.