Activated sludge is caused by bacteria, protozoa and microbial suspended substances, colloidal substances mixed with flocculent particles very strong adsorption ability of the decomposition of organic matter formed together, the flocculent structure has good settleability, make water treatment and sludge separation, and ultimately achieve the purpose of purifying wastewater activated sludge is the key. Activated sludge in the sewage treatment process, the settlement performance directly affects the quality of effluent water. Activated sludge method is widely used in sewage treatment and industrial wastewater treatment, is the most widely used in the city sewage treatment.

A yellowish brown flocculant formed by aeration of air into the sewage. The flocculant is composed mainly of a large population of propagating microorganisms, which is easy to precipitate, separate from water, and purify the sewage. Clarification. This flocculation is called "activated sludge".

In activated sludge, in addition to microorganisms, Microbes and organic compounds form the volatile part of activated sludge (I. E. volatile activated sludge, which accounts for about 70 to 80 percent of all activated sludge). The moisture content of activated sludge is generally between 98 and 99. It has a strong ability to adsorb and oxidize and decompose organic matter.

Activated sludge is cultivated and domesticated by certain methods. The purpose of cultivation is to increase the value of microorganisms to a certain concentration of sludge, and acclimation is to select and induce the mixed microbial community. The microorganism which has the activity of degrading pollutants in the sewage becomes the advantage.

1 inoculation

1.1, inoculation is a process unit that utilizes microbial digestion function, such as hydrolysis, anaerobic, anoxic, aerobic process unit, and inoculation is for the above units.

1.2 according to the different species of microbes, different strains should be inoculated respectively.

1.3, the size of inoculation: the amount of anaerobic sludge inoculation should not be less than 8-10% of water volume, otherwise, it will affect the start-up speed. The amount of aerobic sludge inoculation should generally be no less than 5%. of water. As long as the construction is carried out according to the standard, anaerobic aerobic bacteria can start normally in the prescribed range.

1.4 start time: in particular, strain, temperature and water quality conditions, is an important factor affecting start period. Generally speaking, in less than 20 degrees under the conditions of inoculation and start has some difficulties, especially in winter when running. Therefore, that occurs during the operation of sludge in two dosage activated sludge, hydrolysis acidification pool dosing ratio 8% (sludge), activated sludge in the aeration tank dosing ratio was 10 (% dry sludge concentration, sludge is 8%), under different temperature conditions, adding different proportion. After dosing according to normal water level conditions, continuous aeration and aeration (during the 7 days after the inspection, no water) treatment effect in determining the microbial biochemical condition is normal, can small water continuous feeding for 25 days, until the biochemical effect is obvious or temperatures rise significantly, again to the two pool respectively adding 10% of activated sludge, biochemical process can start normally.

Source: 1.5 strains of anaerobic anaerobic sludge mainly comes from existing projects, such as beer anaerobic fermentation, biogas digesters in rural areas, ponds, a moat dredging sludge; aerobic sludge from city sewage treatment plant, should take the pull of activated sludge dehydration as aerobic bacteria, sludge inoculation and in this order to determine the priority.

The remaining sludge or dehydrated sludge of 1.5.1 similar sewage plant;

1.5.2 surplus sludge or dehydrated sludge in a municipal sewage plant;

1.5.3 remaining sludge or dehydrated sludge from other different sewage stations;

1.5.4 sludge at the bottom of a river or lake;

1.5.5 fecal sludge supernatant.

2 domestication and culture

2.1 acclimation condition

Generally speaking, microbial growth conditions can occur suddenly prominent changes, routine to have a process of adaptation, the domestication process should be consistent with the original growth conditions, when the condition does not have, generally used conventional sewage as water cultivation, acclimation temperature is not lower than 20 DEG C, take continuous aeration acclimation for 3-7 days, and check the microorganism under the microscope, or on the basis of practical experience, according to different processing methods (activated sludge biofilm), observe microbial growth conditions, can also be used to check in and out water COD size to judge biochemical effects.

2.2 domestication

Have 2.2.1 acclimation conditions, continuous operation has seen effect, by increasing the amount of water sewage, enable the microorganism to gradually adapt to new living conditions, increasing the magnitude of the anaerobic aerobic process and site conditions are different. The aerobic start can be completed in 10-20 days, increasing the ratio of 5-10%; while many increasing anaerobic influent ratio will be small, the general should control the volatile fatty acid (VFA) concentration is less than 1000mg/L, and the pH of anaerobic tank should be kept in the range of 6.5-7.5, do not have too much volatility, in this case the water can increase slowly. In general, anaerobic from start to turn into normal operation (full load of water) need 3-6 months to complete.

2.2.2 anaerobic, aerobic, and hydrolyzed biochemical processes are a complex process. Each process has its own characteristics and needs to be adjusted according to the conditions of the field.

2.2.3 compiled the necessary record and report for preliminary laboratory establishment and operation, and established a standardized organization and management mode from the beginning of cultivation.

3 matters of attention

3.1 bacteria in activated sludge process, often should determination of influent pH, COD, ammonia nitrogen and dissolved oxygen in aeration tank, sludge sedimentation performance of activated sludge. After the initial formation, must carry on the biological observation, according to the results of observation on sludge cultivation status was assessed, and the dynamic regulation of bacteria culture.

3.2, the cultivation of activated sludge should be carried out as long as possible in a suitable temperature season. Because temperature is suitable, microorganism growth is fast, and the time for cultivating bacteria is short. If we can only cultivate bacteria in winter, we should adopt inoculation culture method, and the needed sludge is more than that in spring and autumn.

3.3 in the process of culture, especially after the initial formation of sludge, sludge should be taken to prevent excessive self oxidation, especially in the summer. Many plants have occurred in such cases. This not only increases the culture time and cost, and even lead to the sewage treatment system can not be put into operation. To avoid sludge self oxidation, aeration control and the amount of aeration time is the key to determination of dissolved oxygen content, often in the pool, timely water to meet the nutritional needs of microorganisms. If the influent concentration is too low, should be added to the excrement supplement nutrition, when conditions do not have the intermittent aeration.

In the later period of 3.4 active sludge, the proper discharge of some aging sludge is beneficial to the further growth and reproduction of microbes.

3.5 if the sludge in the aeration tank has matured, but there is still no wastewater into, stop aeration sludge dormant, or intermittent aeration (extended aeration time interval, reduce the amount of aeration), as far as possible to reduce sludge self oxidation speed. When conditions should be added excrement, non-toxic organic waste (such as canteens swill and other nutrients).