电刺激条件下初始pH值对剩余污泥厌氧消化效果的影响

在厌氧消化反应器中施加0.6V电压刺激,考察初始pH值(3,5,7,9,11)对剩余污泥厌氧消化效果的影响.结果表明,当初始pH值为9、厌氧消化至32d时,污泥挥发性固体有机物去除率为38.1%,甲烷产率为224mLCH₄/g VS;同样的消化时间内,初始pH值为7的对照组,其挥发性固体有机物去除率为32.2%,甲烷产率仅为162mLCH₄/g VS.调节初始pH值可加速污泥水解酸化过程,其中pH值为11时,水解酸化效果最好,比其他pH值条件下产生更多的挥发性脂肪酸(VFAs).在产酸高峰期,初始pH值为3、11时,乙酸和丁酸是主要产物;初始pH值为5、7、9时,主要产物是乙酸和丙酸.调节初始pH值能加速氨氮的释放,且pH值为酸性(3,5)时的氨氮浓度高于碱性条件下(9,11)的浓度.

Effect of initial pH on anaerobic digestionof waste activated sludge under direct electrical stimulation

Batch tests were operated to investigate effects of initial pH (3,5,7,9,11) on anaerobic digestion of waste activated sludge under 0.6V direct electrical stimulation. Initial pH had a great influence on biogas production and VS removal efficiency. At the optimal initial pH of 9, maximum methane yield of 224mLCH₄/g VS and VS removal efficiency of 38.1% were achieved after 32days digestion. Initial pH could accelerate hydrolysis and acidification process of waste activated sludge. Alkaline environment (pH 9, 11) enhanced SCOD and VFAs concentrations in suspensions, especially at pH 11. Acetic acid and butyric acid were dominant at pH 3and 11while acetic acid and propionic acid were main products at pH 5, 7 and 9. Initial pH facilitates release of ammonium from waste activated sludge and in acidic environment ammonium was released in excess.