Activated sludge strains

Activated sludge bacterial culture method

(1) Intermittent culture.

Fill the aerated biological reactor with water, then stop the water supply and start aeration. Only aeration without adding water is called "muffled aeration". After 2-3 days of aeration, stop aeration, let it settle for 1 hour, then add some fresh sewage, which should account for about 1/5 of the tank capacity. Afterwards, the three processes of anaerobic exposure, static sedimentation and water intake will be repeated in cycles, but the amount of water intake each time should be increased compared to the previous time, and the anaerobic exposure time each time should be shortened compared to the previous time, that is, the number of water intakes will increase. When the temperature of sewage is 15~20℃, this method can be used to make the MLSS in the aerated biological reactor reach above 1000mg/L after about 15 days. At this time, the aeration can be stopped, water can be continuously added and aeration can be continued, and sludge return can be started. The initial reflux ratio should not be too large, and 25% is acceptable. As MLSS increases, gradually increase the reflux ratio to the design value.

(2) Low-load continuous culture.

Fill the aerated biological reactor with sewage, stop the water supply, and aerate for 1 day. Then water is continuously introduced and aeration is carried out, and the water intake is controlled at 1/2 of the designed water volume or lower. When sludge flocs appear, reflow begins with a reflow ratio of 25%. When MLSS exceeds 1000 mg/L, water will start to flow in at the designed flow rate. When MLSS reaches the designed value, reflow will start at the designed reflow ratio and the remaining sludge will begin to be discharged.

(3) Continuous cultivation at full capacity.

Fill the aerated biological reactor with sewage, stop the water supply, and aerate for 1 day. Then, water is continuously introduced at the designed flow rate and aeration is continuously performed. After the sludge flocs are formed, backflow begins. When the MLSS reaches the designed value, the remaining sludge begins to be discharged.

Precautions

(1) In order to increase the culture speed and shorten the culture time, nutrients should be added to the influent water. Small treatment plants can input sufficient amounts of feces, and large treatment plants can allow sewage to bypass the primary sedimentation tank and enter the aeration tank directly.

(2) Temperature has a great influence on the culture speed. The higher the temperature, the faster the culture. Therefore, sewage treatment plants should generally avoid cultivating sludge in winter, but in practice it should also depend on the specific circumstances. If the sewage treatment plant is completed in winter and the conditions for cultivation are met, cultivation can also be started so that the environmental benefits can be realized as early as possible. For example, the Beijing Gaobeidian Wastewater Treatment Plant successfully cultivated activated sludge in about one month in winter.

(3) In the early stage of sludge cultivation, since the sludge has not yet been formed in large quantities and the generated sludge is in a discrete state, the aeration volume must not be too large. It can generally be controlled at 1/2 of the designed normal aeration tank. Otherwise, sludge flocs are not easy to form.

(4) During the culture process, the biological phase should be observed at all times, and indicators such as SV and MLSS should be measured so that the culture process can be adjusted at any time according to the situation.