An anaerobic sequence batch process carried out in a single vessel. The biological reactions occur under anaerobic conditions and the vessel is operated on a fill-and-draw basis in a sequential manner. When waste is entering the reactor, the vessel is mixed by biogas or liquid recirculation. Waste feeding continues until the reactor is filled to its predetermined full liquid level. The anaerobic reaction proceeds with intermittent or continuous mixing. Mixing is then discontinued, allowing the biomass to settle under quiescent conditions resulting in the formation of a low suspended solids supernatant. After sufficient time in the settling cycle, supernatant is withdrawn from the reactor lowering the reactor contents to the predetermined lower liquid level. Gas or liquid recirculation mixing is then begun again along with waste feeding. Excess biomass is wasted from the reactor on a periodic basis. The capacity of the reactor depends on the number of feeding-clarification-wasting cycles that can be achieved in a day.

Anaerobic sequencing batch reactor

A complete mix activated sludge basin is operated as a Sequence Continuous Reactor by cyclically aerating the mixed liquor to form an aerobic cycle at selected high dissolved oxygen levels, during which nitrification takes place, and cyclically mixing the liquor without aerating to form anoxic cycles at selected low dissolved oxygen levels, during which denitrification takes place. Field adjustments can be made by the operator in the dissolved oxygen levels and in the duration of the aerobic and anoxic cycles, whereby ammonia removal, nitrification, and denitrification can continue to be done efficiently during both summer and winter temperature conditions, during conditions varying from warm to cold inlet wastewater temperatures, during extreme variations in food supply, and during pronounced variations in biomass concentration and activity.

Sequence continuous reaction in complete mix activated sludge systems

In a wastewater treatment system and process utilizing membrane bioreactors (MBRs), multiple, parallel series of tanks or stages each include, an MBR stage. Under conditions of normal flow volume into the system, influent passes through several parallel series of stages or process lines, which might be, for example, an anoxic stage, an aeration stage and an MBR stage. From the MBR stages a portion of M.L.S.S. is cycled through one or more thickening MBRs of similar process lines, for further thickening and further processing and digesting of the sludge, while a majority portion of the M.L.S.S. is recycled back into the main process lines. During peak flow conditions, such as storm conditions in a combined storm water/wastewater system, all of the series of stages with their thickening MBRs are operated in parallel to accept the peak flow, which is more than twice normal flow. M.L.S.S. is recycled from all MBR stages to the upstream end of each of all the parallel process lines, mixing with influent wastewater, and the last one or several process lines no longer act to digest the sludge. Another advantage is that with the thickened sludge in the last process line of basins, which ordinally act to digest the sludge, there is always sufficient biomass in the system to handle peak flow, the biomass being available if needed for a sudden heavy flow or an event that might bring a toxic condition into the main basins.

Wastewater treatment system with membrane separators and provision for storm flow conditions

The present invention relates to a system and method for biologically removing nitrogen from wastewater. Both the system and method entails forming a mixed liquor and transferring the mixed liquor to a series of nitrogen removal stages. Each nitrogen removal stage includes both anoxic and aerobic treatment zones. Mixed liquor is recycled back and forth between the anoxic and aerobic treatment zone of each stage. Because of this basic flow scheme, the process gives rise to a high reactor rate and highly efficient nitrogen removal process.

Method for biologically removing nitrogen from wastewater

The invention relates to a system and a process for purifying nitrogenous waste water by biological nitrification and denitrification. The system comprises at least two essentially separated reactor chambers, a liquid supply (4) and a liquid discharge (5). The first, aerated reactor chamber (1) is provided at the top with an overflow to the second, oxygen-depleted reactor chamber (2). The oxygen-depleted reactor chamber (2) is divided at the top into a degassing chamber (7) and a settling chamber (8) having an overflow (9) to the liquid discharge. The first reactor chamber is provided with an air supply (11, 18) and an air discharge (12) located above the supply. The first reactor chamber may be partly divided into a riser (14) and a downcomer (15) which allow, as a result of the air supply, mass circulation to take place in the aerated reactor chamber. According to the process, waste water with bacterial sludge on a carrier circulates alternately through the oxygen-depleted and the aerated reactor chambers, whereafter it is separated from the sludge and the sludge is returned to the reactor.

System and process for purifying waste water which contains nitrogenous compounds

A process for treating wastewater to biologically remove phosphorous as well as lowering ammonia, TSS and BOD levels is provided. The process employs a plurality of basins which may be individually controlled to achieve anaerobic, anoxic or aerobic conditions. The basins are reconfigurable in that the flow of influent to a basin, transfer of mixed liquor between basins and effluent discharge from a basin can be varied to create a treatment cycle which has features of both continuous and batch processes while minimizing recycle rates and hydraulic level changes.

Raleigh L. Cox

Papers

Biological phosphorous removal from wastewater using multiple recombinable basins