Study On The Effects Of Vermicompost Supplementation On Startup Of The Aerobic Treatment Reactor

Aerobic aerated treatment has features of small structures, short aerated time, high efficiency, good effluent quality, flexible operation, and low expense, which made it widely used in various types of wastewater treatments. SBR has become one of the primary ways in wastewater biological treatments which is suitable for the situation of our country because of its efficient, economical and reliable characteristics. How to cultivate high activity and good settle-ability activated sludge is the key to this technology. In many ways of enhancing the sludge activity and granulation, throwing in additives has been paid much attention as an effective way. Vermicompost, as the product of earthworms’processing of organic solid waste, has high porosity and specific surface area, good drainage, and high water holding capacity, and contains many kinds of nutritive elements and microbial flora. It plays a significant role in promoting anaerobic fermentation. These special functions probably have a certain influence on the startup of biochemical treatment reactor. But so far, the research in this area has rarely been reported.In this text, using worm excretion as the experimental material to simulate the SBR operation mode, increased different quality gradient wormcast to different concentrations of sludge, and selected the suitable quantity of wormcast through analyzing the COD from every period of effluent; Determined the effluent each hour to study the dynamic response of OM with the wormcast; Studied the influence on water quality when adding wormcast to the reactor under different temperatures; Discussed the concentration change of the COD of the effluent under different methods of wormcast addition; Analyzed the response to the start-up time when adding the wormcast under the condition of different concentrations of the flooding water; Studied the influence on the reactor when replacing sludge with sludge earthworm, in order to find out new starter to the reactor of the aerobic treatment of domestic sewage. The main findings are as follows:1. The addition of wormcast had certain facilitation to the startup of the reactor. Under the temperature of30℃, the low concentration of sludge had obvious effect when adding the equal quality of wormcast, while the lowest quality of wormcast had the best effect under the condition of the same concentration of sludge, and the effect was the second best when the ratio of the transaction of sludge and wormcast in the quality was2:1.2. Analysis of the COD removal rates by adding wormcast revealed that the microorganisms in the wormcast began to adapt to the water environment and work mainly in the running period’s second phase.3. Under different temperature conditions, the effects of adding wormcast in the startup of the reactor were different. At low temperatures, the best amount of adding wormcast was when the ratio of sludge and wormcast quality was2:1, and when the concentration of sludge was high, the effect on starting up the reactor was obvious. With temperature increasing, the adding amount of1:1had advantage at15℃. When the temperature came to25℃, the outlet water quality was the best, and under the condition of low concentration of sludge, adding wormcast could not only speed the reactor startup, but also save the amount of sludge used. The outlet water quality at35℃was better than15℃, but poorer than25℃.4. If a short-time startup of the reactor was needed under the condition of low concentration of sludge, one-time addition was a good choice. However, if considering the water stability, a two-time addition should be the choice. When the sludge concentration was high, multiple-addition could diminish the sludge load so as to get better effect of COD removal.5. When COD concentration was higher than400mg/L, adding wormcast could also speed up the startup of the reactor. The increase of COD resulting from wormcast could be degraded early in the2-3running period.6. Sludge-wormcast didn’t had a better effect in startup of the reactor, but using it to vaccinate sludge and adding wormcast could obtain a better COD removal effect.7. Adding wormcast in the reactor could heighten the sludge flocculating effect and has some inhibitory effects on sludge bulking.This study has initially found that adding wormcast had some effects on enhancing the activity of microorganisms. However, more micro level test such as the microorganism’s constitutions and patterns of sludge and wormcast in the case of reactor startup should be carry on. Study on the specific action mechanism of adding wormcast in startup of the reactor would make more accurate application of wormcast in wastewater treatments.