| The purification of the swine biogas slurry with micro algae would be disrupted severely due to complex ingredient in the swine biogas slurry, especially the existence of protozoa and epigenetic miniature animals. And than the swine biogas slurry had continuous large quantity of emission. So the swine biogas slurry pretreatment and the design of the reactor using micro algae to process swine biogas slurry become the two difficult points of this technology. The main results were as follows:Through biological observation in the process of breeding the micro algae in swine biogas slurry, found that there were protozoa and epigenetic miniature animals, for exemple rotifers, vorticella, paramecia, amoeba in swine biogas slurry and learned that swine biogas slurry had complex microbiota. Using different methods to deal with pests in swine biogas slurry, found that effects of40mg/L bleaching powder, heating boiling,0.05%ammonia and adjusting the pH to12were very ideal among those methods, but comprehensive consideration of effects and costs,40mg/L bleaching powder and adjusting the pH to12two methods were convenient and feasible, and the costs were lower, respectively, just for0.050yuan/ton and0.295yuan/ton, so these two methods were suitable for large-scale continuous operation of the system of swine biogas slurry pretreatment.Through the growth of micro algae in biogas slurry processed with several methods, it could be seen that two methods processing swine biogas slurry, heating boiling and40mg/L bleaching powder, had minimal effects on breeding micro algae with processed swine biogas slurry. But considering the cost and the practical operation,40mg/L bleach powder was more reasonable. Then by further experiments, found that swine biogas slurry need to be put no less than4days and then to vaccination when processed by40mg/L bleaching powder. Designing and building a continuous system of using micro algae to treat the swine biogas slurry, changed the separate study for micro algae and vaccination, micro algae breeding, micro algae purifying wastewater, microalgae harvesting in the past. It made these techniques fused together and provided certain theoretical basis and engineering for large-scale use of using micro algae to purify swine biogas slurry. Layer decay algal photosynthetic organisms reactor was constructed according to the principle of bionics, can not only increased the photosynthetic efficiency, also good saved area by developing to the space, it was also one of the key technical achievements of this research.Through experiments for the algal growth conditions found that effect of light on the growth of microalgae group was the largest, temperature and aeration came second; By the influence of using microalgae group to purify swine biogas slurry by adding the activated sludge and aeration, found aeration and adding activated sludge could promote purification of biogas slurry, but adding activated sludge could affect the accumulation of micro algae biomass.Through effects of different inoculation ratio on purifying swine biogas slurry in designed and processed reaction system, found that when the inoculation ratio was50%, the swine biogas slurry could be purified very well after seven days, making COD, TN, NH3-N, TP, SS in waste water, decreased to184.58mg/L,90.52mg/L,46.05mg/L,7.86mg/L,32.13mg/L respectively, and the removal efficiency of were76.7%,72.4%、80.3%,73.8%,95.4%respectively. The purified swine biogas slurry had reached the national standard of wastewater discharge standard for swine industry, and reached the maximum capacity. So the system completely reached the expected purpose. |
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