Studies On Growth Enhancement Methods For Outdoor Cultivation Of Microalgae In Raceway Pond Using Municipal Sewage

Cultivating high-lipid microalgae by municipal sewage to produce bio-diesel can not only ease the increasingly serious energy crisis, but also alleviate the water pollution. Increasing the biomass and the fat yield of microalgae is an important part to reduce th e cost and the source of the whole process running smoothly. This paper aims to outdoor cultivate microalgae by municipal sewage and then find a optimal combined enhancement method to maximize the growth of the microalgae and increase the biomass and fat yield, in order to improve the economic feasibility of microalgae biodiesel.Through the outdoor experiments, finding out that three growth enhancement methods(magnetic field, plant hormones and bacteria) all have a great effect on promoting the growth, dr y weight and oil production of Chlorella pyrenoidosa which cultivated by municipal sewage and getting the optimum condition of each enhancement methods. Then studied the effect of the combination of these three methods on Chlorella pyrenoidosa. By orthogon al experiment, determined the optimal combination which can mostly enhance the growth and oil accumulation of Chlorella pyrenoidosa outdoor cultivated by municipal sewage. The optimal combination could be effective in outdoor raceway pond cultivation. In the batch culture, OD value increased by 8.06%, chlorophyll concentration increased by 43.94%, algae dry weight increased by 17.85%, oil production increased by 27.54%. In the semi-continuous culture, the best update rate was determined to be 25% and the oil production of algae could be 0.18 g/L. The whole culture process worked stably and the concentrations of a number of municipal wastewater pollutant s had decreased. The reasons for the growth enhancement of Chlorella pyrenoidosa were discussed. The external stimulus made algal photosynthetic pigment content increased, which increased the algal photosynthesis. The activity of the antioxidant enzymes in algal cells increased, promoted the growth of algae. In addition, magnetic treatment ma de the light transmittance of the medium increased, which was beneficial to the absorption of light energy. Photosynthetic bacteria c ould regulate the culture of p H, improve the growth environment and promote the growth of Chlorella pyrenoidosa.