초록 ▼

The present invention relates to a process and a treatment system for biologically removing phosphorus and nitrogen from wastewater. In the anaerobic contact and settlement zone 1, wastewater 7 is first mixed with the returned activated sludge 8 to form a mixed liquor which is then allowed to settle

The present invention relates to a process and a treatment system for biologically removing phosphorus and nitrogen from wastewater. In the anaerobic contact and settlement zone 1, wastewater 7 is first mixed with the returned activated sludge 8 to form a mixed liquor which is then allowed to settle in zone 1, and organic matters present in influent are mostly taken up by the sludge. The supernatant from zone 1 is passed through an aerobic reaction zone 2, furnished with packings, for complete nitrification; the settled sludge from zone 1 is hold in an anaerobic zone 3 for a sufficient period of time for controlling the sludge carbohydrate content to low levels in order to enlarge the sludge capacity for phosphorus removal because the extended anaerobic sludge degradation in zone 3 is very effective in controlling the sludge carbohydrate content to low levels. The sludge from zone 3 is then allowed to be remixed with the nitrified supernatant from zone 2 in zone 4, where the products of the extended anaerobic reaction allowed very high denitrification rates and efficiencies. The aerobic zone 5 is supplemented to complete phosphorus uptake by the activated sludge, in which the dissolved oxygen (DO) level is controlled at relatively low levels in order to limit the aerobic synthesis of sludge carbohydrate. The aerated mixed liquor is then transferred into a final clarifier where settled sludge is separated from purified supernatant. At least a portion of the settled sludge is recycled back to zone 1 to be mixed with raw wastewater, while a portion of the settled sludge is wasted.

대표청구항 ▼

[ We claim:] [1.] An activated sludge process for biological removing phosphorus, nitrogen nutrients from wastewater, which comprises the following steps:(1) anaerobic contact/separation, mixing raw wastewater which contains phosphorus, nitrogen and organic matters (measured as COD) with returned ac

[ We claim:] [1.] An activated sludge process for biological removing phosphorus, nitrogen nutrients from wastewater, which comprises the following steps:(1) anaerobic contact/separation, mixing raw wastewater which contains phosphorus, nitrogen and organic matters (measured as COD) with returned activated sludge to form a mixed liquor, and then allowing the mixed liquor to settle to separate settled sludge from the supernatant; (2) aerobic nitrification, EASD and sludge carbohydrate content control (SCCC), the supernatant being nitrified under aerobic condition by fixed membrane of nitrifing microorganism, while the separated sludge being held under anaerobic conditions for a sufficient period of time in order to enlarge the sludge capacities for phosphorus removal and to control the sludge carbohydrate content to low levels; (3) anoxic denitrification, transferring and re-mixing the nitrified supernatant and the sludge, which has been anaerobically held for a period of time in last step, in a zone of anoxic conditions so that nitrate and nitrite present in the supernatant are denitified by the sludge; wherein phosphorus in the liquid phase is at least partially, taken up by the sludge; (4) aerobic phosphorus uptake, transferring and aerating the denitrified mixed liquor from last step, to enable the microorganisms in the sludge to take up phosphorus from the liquid phase; (5) settlement separation, transferring the aerated mixed liquor to a final settlement separation zone where settled sludge of high phosphorus content is separated from purified supernatant; and (6) recycling at least a portion of the settled sludge back to re-contact with raw wastewater. [4.] A wastewater treatment system suitable for biological phosphorus and nitrogen removal of claim 1, comprising a sludge-wastewater contact/separation tank, an EASD tank, a packing nitrification tank, a denitrification tank, an aerobic tank and a final settling tank; said sludge-wastewater contact/separation tank consisting of a sludge-wastewater mixing zone and a settlement separation zone, located at the downstream of preliminary settling tank which is optional; said the EASD tank being a sludge tank, located at downstream of the sludge-wastewater contact/separation tank; and packing nitrification tank being a wastewater tank, located at the downstream of the sludge-wastewater contact/separation tank, equipped with aerators for oxygen supply and also packed with packings which support physically the growth of membrane of microorganisms especially of nitrifying microorganism; said denitrification/nitrogen removal tank being a sludge-wastewater mixed liquor tank located at downstream of the EASD tank and the packing nitrification tank and equipped with stirrers; said the aerobic tank being a sludge-wastewater mixed liquor tank, located at the down stream of the denitrification/nitrogen removal tank and equipped with aerators to maintain the dissolved oxygen (DO) to certain levels; said final settling tank located at downstream of the aerobic tank to separate sludge from supernatant.