Membrane filtration with rapid pretreatment using adsorbent of submicron particle size

将生产厂家提供的普通粉末活性碳粉碎，使其颗粒尺寸小于1μm，我们称之为超细粉末活性碳(S)。研究了S-PAC与普通PAC相比，在吸附去除天然有机物(NOM)和土豆素(霉土气味和气味成分)方面的优势。间歇吸附动力学试验和管流反应器试验表明，S-聚合氯化铝能快速吸附水样中的硝酸铵。投加S-PAC后，NOM浓度迅速下降，在接触时间为5 S时达到一个可实际去除的平台期。接下来，采用小试和中试装置研究了S-PAC吸附作为微滤(MF)的前处理工艺。使用S-PAC可显著缩短微滤前吸附预处理的滞留时间。S滞留时间为2.4时，微球渗透液中的硝普钠浓度与滞留15min时的浓度相同。S-聚合氯化铝的投加量也比常规聚合氯化铝减少了1/4。投药顺序为：聚合氯化铝>混凝剂>微滤，对有机物的去除效果略好于混凝剂>聚合氯化铝>微滤，说明聚合氯化铝颗粒的絮凝作用在一定程度上阻碍了吸附在聚合氯化铝颗粒中的吸附。用这种S-PAC进行吸附预处理，脱除土豆素的效率比普通PAC要高得多。在更短的接触时间和更低的剂量下实现了去除。S-PAC还有利于减弱物理反冲洗和化学清洗之间的跨膜压升。在膜过滤前投加S-PAC没有观察到膜污染效应。

Normal manufacturer-supplied powdered activated carbon (PAC) was pulverized to reduce the PAC particle size to less than 1 μm; we call the pulverized PAC super-powdered activated carbon (S-PAC). Advantages of S-PAC over normal PAC, mainly in terms of adsorptive removal of natural organic matter (NOM) and geosmin (musty-earthy taste and odor compund), were studied. Batch adsorption kinetic tests and tubular flow reactor tests revealed that S-PAC rapidly adsorbed NOM from water samples. NOM concentration rapidly decreased after S-PAC addition and reached a plateau of practically attainable removal in a contact time of 5 s. Next, S-PAC adsorption as a pretreatment for microfiltration (MF) was studied by using laboratory-scale and bench-scale pilot plants. Use of S-PAC could decrease significantly the detention time for adsorption pretreatment before MF. A detention time of 2.4 s yielded the same NOM concentration in the MF permeate as a detention of 15 min. Use of S-PAC could also decrease the dosage compared with normal PAC by a factor of 1/4. The dosing sequence, PAC followed by coagulant and then MF, showed slightly better NOM removal than the sequence, coagulant followed by PAC and then MF, suggesting that flocculation of PAC particles somewhat hinders adsorbate uptake into PAC particles. Adsorption pretreatment by using this S-PAC removed the geosmin with vastly greater efficiency than by normal PAC. Removal was attained in a much shorter contact time and at a much lower dosage. The S-PAC was also beneficial in attenuating the trans-membrane pressure rises that occurred between both physical backwashings and chemical cleanings. No membrane fouling effect was observed as a result of S-PAC addition before MF.