Study On Formation Process And Cultivating Conditions Of Mycelial Pellets

In the wastewater treatment process, it is easy to add in bacteria directly, but the bacteria is also easily missing, or being swallowed by other microorganisms. Immobilized Microbe Technology (IMT) can fix free microorganisms on carriers with a high concentration and keep their activity. IMT makes the wastewater treatment system operate efficiently and stablely. Mycelial pellet is a kind of bio-granule that can from spontaneously in the process of ferment. It has a good biological activity, fast sedimentation velocity, and no need for carrier, good condition of liquid solid separation. It can be used in the treatment of wastewater with heavy metals and dye. However, actual wastewater is a complex system, complex water ingredients and microbial mutagenesis of different environmental factors make it difficult to form mycelial pellets in it. Therefore, usimg the mycelial pellet as a carrier, adopting the"mixed bacteria self-immobilization technology", to establish a micro-ecology environment made up of mixed bacteria group, in order to let all kinds of immobilized microorganisms play its role together, will become a focus in the field of wastewater treatment.After determining the optimum medium for mycelial pellets, the formation process of mycelial pellets and the impact factors were studied in this paper. So did the formation mode and the impact factors of compound pellets. The purification effectiveness of the preliminary was studied.The optimum carbon source of Aspergillus Y3 mycelial pellets was saccharose and the optimum nitrogen source was ammonium chloride. Fe²⁺ and Mg²⁺ are important trace elements for myceilal pellets. The process of pellet formation can be separated into three stages: spore nuclues sprout and mycelium outgrow; mycelium grow further, and at the action of external force form pellet; as mycelium regrow, pellet autolyze for the mal-condition of culture.Best conditions for mycelial pellets to form and its forming mechanism was studied. We ascertain that when the inoculum concentration is 104 spores per milli-litter, the cultrure temperature is 37℃, the initial culture pH is 5, the revolution of shaking table is 160rpm, mycelial pellets will be at the best station.The forming mode of compound pellets was studied, experiment results showed that the compound pellets can be cultivated through both self-flocculation and adsorption. Compound pellets which were cultivated from Aspergillus spores and bacteria experienced the following four stages : bacteria participate in spores'cohesion, and form a saturated nucleus with spores; bacteria in saturated nucleus grow, spores in saturated nucleus sprout mycelium; under the shear stress in water, the mycelia extend and twist around the nucleus to enwrap bacteria and keep them attach to the mycelia; compound pellets form , and continue growing. In the experiment of compound pellets forming through adsorption, under this condition (the initial pH of aniline degradation rhizomorph suspension is 6.0 7.0, rotation speed of 140 rpm, 25 35℃, the diameter of mycelial pellet is 1.2 1.8mm), compound pellets of good condition could form.The compound pellets had a certain purification efficiency. The removal of aniline was up to 82.45%. SEM photographs showed that the microorganisms immobilized firmly on the mycelium with good conditions. This establish theoretical basis for pellet being used as a new kind of carrier in the process of water treatment.