Effective Microorganism Applied In Reduction Of Septic Tank Sludge

The septic tanks will still be widely used as wastewater pretreatment facilities in the long transitional period of being improved on the system of urban sewage pipe and wastewater pretreatment facilities. If Night soil sludge retained by the septic tanks is not be clean up in time, the overflow of night soil will pollutes the environment seriously. It also results in the Potential security risk such as methane poisoning or exploding if daily maintenance on the septic tanks is imperfect. Sometimes solidification hardened layer on the surface of bodies of water is not be clean up and hardened, which will reduce in the effective cubage of the septic tanks virtually and shorten the residence time that degrades the water quality of effluent. For all some new model of septic tanks have be developed recently such as methane septic tanks, integrated biological septic tanks, ecological septic tanks and Conservation septic tanks. Due to the city of Chongqing has a long history on construction, million of the septic tanks belonged to traditional septic tanks of three-lattice type that is hard to update on basic structure to the new type of septic tanks. The burning and exploding of methane or exhausting of odorous gases in the septic tanks frequency occur in the urban of Chongqing due to the aging of equipment and poor drainage in most of the existed septic tanks.In this dissertation, based on the practical situation of Septic Tank of Chongqing Municipality, reduction of Septic Tank sludge treated with microbial technology (bacteria of EM ) in combination with anaerobic digestion had been explored. Technical conditions and influencing factors of Septic Tank sludge treatment with EM had been researched in this exploratory testing , and provided the basis for reduction of Septic Tank sludge, enhancing effluent cleanliness of Septic Tank and removing hidden dangers for block of Septic Tank. All aspects of the above study , the following main conclusions:(1) Feasibility study of treatment of Septic Tank sludge with EM showed that: The corporate effect of EM and the original microorganism of the nightsoil sludge system is more propitious to reduce septic tank nightsoil sludge, it is feasible for adding EM to septic tank directly to reduce nightsoil sludge production.(2) Study of adding concentration of EM to Septic Tank sludge reduction impact showed that:1) Proper addition of EM can enhance the buffering capacity of the system on acid-base, keep the ammonia-nitrogen concentration lower than inhibition concentration of 2000mg/L in anaerobic reaction and maintain certain range of pH value which is fitting for acidified hydrolysis and methanogenic. Overdose of EM can lead the system of septic sludge to be acidified and decrease the effects of the anaerobic digestion. 2) Addition of EM can increase the microbe quantity and improve the gas production and generation rate in a certain period time. But overdose EM can decrease the system pH value and inhibit activity of methanogenic bacteria. 3) In this experiment, 0.01% is the optimal adding concentration of EM.(3) Study of pH value of EM to Septic Tank sludge reduction impact showed that: 1)Alkaline pretreatment can improve reduction effect of Septic Tank sludge with EM, and the best reduction effect appeared in pH=10; suitable pH value range of (7～8) can improve gas production of the system, but it would inhibit gas production of system when pH value is greater than 9; system can control the ammonia concentration in a certain range with alkali pretreatment, and responsed to avoid the phenomenon of inhibition. 2)Acid pretreatment reduced the effect of sludge reduction and lead to inhibition of gas production and instability of system. 3)The results showed that: alkaline pretreatment is superior to acid pretreatment in sludge reduction.(4)The research on the impact of temperature value of EM to Septic Tank sludge reduction showed that: 1) There exists great effect with the temperature on reduction of TS,VS,COD in the septic-tank sludge anaerobic digestion to EM. The reduction rate on TS , VS and COD is best when the temperature is 35℃, which takes second place when the temperature is 45℃and 25℃is the worst.2) At the same time of decrement on the septic-tank sludge anaerobic digestion to EM, there exists the positive effect on reduction of TP, which the best effcet appears at 35℃. 3) The accumulation of NH₄⁺-N is the most high at 45℃and the worst appears at 25℃, the effect at 35℃is the middle. at the end of the reaction period with 20 day, the content of NH₄⁺ in E45 is more than 2000 mg·L^-1 reported by the literature on inhibition concentration of anaerobic digestion. The anaerobic digestion is under control on some degree. 4) pH value range of (7.29～7.74) of anaerobic digestion system in the 25⁴5℃can satisfy coexistence of acid bacteria and methanogenic bacteria.(5)In this experiment the best deal conditions of septic tank sludge with integrated single-factors of the impact of septic tank sludge reduction research by adding EM show that: adding concentration of EM is 0.01%, adjust pH=10 and temperature 35℃. Under these conditions, the system can accelerate the reduction of sludge, inhibit gas production , restrain bad smell and eliminate potential safety hazard.