以PHAs为固体碳源的城镇二级出水深度脱氮研究

利用从连续运行的缓释碳源滤料滤池中取出的聚羟基脂肪酸酯(PHAs)颗粒,研究了微生物和硝酸盐对其的总有机碳(TOC)释放速率的影响,并研究了温度、pH值、硝态氮浓度对其反硝化速率的影响.结果表明:原有的和附着有微生物的PHAs颗粒在去离子水中TOC释放速率分别为0.030,0.053mg/(g·d),远低于水中有硝酸盐时的TOC释放速率进水NO3--N为30mg/L时,TOC释放速率为0.533mg/(g·d)].温度和pH值对反硝化速率影响较大, pH值为7.5时,在15~35℃范围内, 30℃下的反硝化速率最大,为0.067mg/(g·h);温度为30℃时,pH值在6.0~9.0范围内,pH值为7.8时的反硝化速率最大,达到0.061mg/(g·h).反硝化速率与NO3--N浓度之间的关系符合Monod方程,最大反应速率和半饱和常数分别为4.74mgNO3--N/(gSS·h)和56.6mg/L.

Tertiary nitrogen removal of the municipal secondary effluent using PHAs as solid carbon sources

Polyhydroxyalkanoates (PHAs) pellets, which were taken from a denitrification biofilter with sustained-release carbon source materials, were used to investigate the effects of microbes and nitrate on the organic carbon release rate of PHAs and the effects of temperature, pH and NO3--N concentration on the denitrification rates. The results indicated that the total organic carbon (TOC) release rates of original PHAs and those with biofilm attached were determined to be 0.030 and 0.053mg/(g·d) in the deionized water, respectively, which were much lower than that of 0.533mg/(g·d) in simultaneous presence of microbes and nitrate (30mg/L of NO3--N concentration). The effects of temperature and pH on denitrification rates were significant. When influent NO3--N concentration was 50mg/L, the maximum denitrification rates achieved to 0.067mg/(g·h) at 30℃ in the temperature range of 15 to 35℃, and to 0.061mg/(g·h) at pH7.8 in the pH range of 6.0 to 9.0. The relationship between denitrification rates and NO3--N concentrations appeared to be in good agreement with Monod Equation, and the maximum denitrification rate and the saturation constant were 4.74mgNO3--N/(gSS·h) and 56.6mg/L, respectively.