Cultivation of sludge in the commissioning process of sewage treatment

Activated sludge has a variety of cultivation methods, but different methods require different cultivation time and human and material resources. Cultivation methods should be selected according to the quality of wastewater, climate and actual permitted conditions. 1. Preparation work before cultivation (1) Each structure is built, and clear the pool to remove the construction garbage, the static pressure test proves that there is no leakage, no sinking displacement, and finally acceptance is qualified according to the relevant regulations. (2) Electrical, mechanical, piping and all other equipment is completed and normalized by stand-alone test and linkage test. Finally, it is accepted according to the relevant regulations (instructions). (3) According to the needs of future operation and management, the conditioned sewage treatment plant (station) needs to carry out the most basic routine laboratory tests, such as pH, water temperature, COD, biological phase, etc., to guide the activated sludge cultivation process and daily operation. (4) basic data survey mapping, including sewage flow day and night changes, water quality (pH, water temperature, COD, nitrogen, phosphorus, toxic substances, etc.) and its changes, the technical parameters of various facilities and equipment. Where possible, it is best to receive water (such as acceptance of sewage rivers, etc.) background water quality survey for the record, in order to examine the impact of a number of years on the receiving water body to provide a basis. (5) according to the treatment of water quality conditions to prepare the necessary nutrients (carbon, nitrogen, phosphorus), in order to prepare for what is lacking to make up for what. Adopting inoculation cultivation method, it is also necessary to prepare enough dry (or thickened) sludge of other sewage treatment plants (stations) with similar sewage properties as strains for microbial cultivation of activated sludge. (6) The operator should be familiar with the pipeline arrangement of the whole system and the situation of public works, and understand the basic process of sludge culture and control requirements. (7) Personnel in place, since the culture and domestication should generally make the system continuous operation, not off people. (8) Preparation of the necessary laboratory tests and operation of the original record statements and the initial establishment of rules and regulations. From the beginning of the cultivation of bacteria, and gradually establish a more standardized organization and management mode, to ensure that the start and the formal operation of the orderly progress. 2. Natural cultivation of bacteria Natural cultivation of bacteria, also known as direct cultivation of bacteria. It is the use of wastewater in the original small number of microorganisms, gradually propagate the culture process. Municipal wastewater and some of the nutrients, less toxic industrial wastewater, such as food factories, meat processing plant wastewater, you can consider this cultivation method, but the cultivation time is relatively long. Natural cultivation of bacteria can be divided into intermittent cultivation and continuous cultivation of two kinds of bacteria. (1) Intermittent cultivation. Aeration pool filled with wastewater, muffled aeration (i.e., only aeration and not into the wastewater), after a few days to stop aeration, static precipitation 1 h, and then discharged from the pool about 1/5 of the upper layer of wastewater, and injected the same amount of fresh sewage. So repeated mulled aeration, static precipitation and water into the three processes, but each time the amount of water to increase than the last time, and mulled aeration time to be shorter than the last time. In the spring and fall seasons, about two or three weeks can be initially cultivated sludge. When the sludge concentration of the aeration tank mixture reaches about 1 g/liter, water and aeration can be fed continuously. Because of the low sludge concentration at the initial stage of cultivation, the sludge accumulated in the settling tank is also less, and the return flow should be less, and thereafter, with the increase of sludge volume, the return flow sludge volume should be increased accordingly. When the sludge concentration reaches the concentration required by the process, normal operation can be started and controlled according to the process requirements. (2) Continuous cultivation of bacteria. The first aeration tank into the full wastewater, and then stop the water intake, bored aeration half a day to a day after the continuous water intake. Continuous aeration, water intake from small to large gradually increased, continuous operation for a period of time (about the same as the intermittent method), there will be activated sludge and gradually increase. When the amount of sludge in the aeration tank reaches the concentration required by the process, it is controlled according to the process requirements. As the natural cultivation method is to use wastewater to cultivate activated sludge directly, the cultivation process is also a microorganism gradually adapted to the nature of wastewater and the process of domestication. 3. Inoculation cultivation The culture time of inoculation cultivation method is relatively short, and it is a commonly used activated sludge cultivation method, which is applicable to most of industrial wastewater treatment plants. Municipal wastewater treatment plant, such as nearby seed mud, can also be used to shorten the cultivation time. Inoculation culture method is commonly used as follows: (1) Concentrated sludge inoculation culture. Use the concentrated sludge of the nearby sewage treatment plant as the strain (seed mud or seed sludge) to cultivate. Municipal wastewater and nutrient complete, low toxicity of industrial wastewater treatment system of activated sludge culture, can be directly in the wastewater to be treated by adding seed sludge for aeration, until the sludge turns brownish yellow can be continuous into the sewage (water intake should be gradually increased), at this time, the sedimentation tank is also put into operation, so that the sludge circulation in the system. In order to speed up the cultivation process, unfermented manure water or other nutrients can be added during the cultivation process. The activated sludge concentration reaches the value required by the process, which completes the cultivation process. Economically speaking, the amount of seed sludge should be as small as possible, generally controlled in the dilution to make the mixture of sludge concentration of 0.5g / L or more. Cultivation of toxic industrial wastewater, the first aeration tank can be introduced into the river, can also be used to tap water (need to be aeration for a period of time in order to remove the residual chlorine), and then put into the seed sludge and unfermented fecal water for aeration until the sludge is brownish-yellow after stopping the aeration to allow the sludge to settle and drain off a portion of the supernatant, and then replenish a certain amount of fecal water to continue to aeration, to be a significant increase in the amount of sludge, and then gradually improve the Wastewater flow. In the later stage of the cultivation of bacteria, microorganisms in the sludge has been able to better adapt to the industrial wastewater quality. (2) Dry sludge inoculation cultivation. "Dry sludge" usually refers to the mud cake after dewatering by dewatering machine, and its water content is about 70-80%. This method is suitable for remote areas and the transportation distance of the seeded sludge. The process of dry sludge inoculation and bacterial cultivation is basically the same as the concentrated sludge bacterial cultivation method. Inoculation of sludge to be used first just dewatered shortly after the fresh mud cake, added to the aeration tank before the need to add a small amount of water and pounded into a slurry. The amount of dry sludge is generally 2-5% of the volume of the tank. Dry sludge may contain a certain concentration of chemicals (used in sludge conditioning), such as high content of chemicals, toxicity, it is not suitable for use as a bacterial seeding mud. Identify whether the sludge can be used for inoculation, a small amount of mud can be crushed into small containers (such as beakers or plastic buckets) with water aeration, after a period of time if the mud color can be turned yellow, it can be used for inoculation.