Membrane filtration with rapid pretreatment using adsorbent of submicron particle size

将普通厂家供应的粉状活性炭（PAC）粉碎，使PAC粒度小于1 μm；我们称其为超级粉末活性炭（S-PAC）。研究了S-PAC在吸附去除天然有机物（NOM）和土臭素（霉味和气味化合物）方面优于普通PAC的优点。间歇式吸附动力学试验和管流式反应器试验表明，S-PAC对水样中的NOM具有快速吸附作用。添加s - pac后，NOM浓度迅速下降，并在5 s的接触时间内达到实际可去除的平台。接下来，通过实验室规模和实验室规模的中试装置研究了S-PAC吸附作为微滤（MF）的预处理。使用S-PAC可显著缩短MF前吸附预处理的停留时间。2.4 s的滞留时间与15 min的滞留时间在MF渗透液中产生相同的NOM浓度。与普通PAC相比，S-PAC的使用也可以减少1/4的剂量。混凝剂→混凝剂→MF的投加顺序对NOM的去除率略好于混凝剂→PAC→MF的投加顺序，说明PAC颗粒的絮凝在一定程度上阻碍了PAC颗粒对吸附质的吸收。使用该S-PAC吸附预处理去除土臭素的效率远远高于普通PAC。在更短的接触时间和更低的剂量下实现了去除。S-PAC还有助于降低物理反冲洗和化学清洗之间的跨膜压力升高。在MF前添加S-PAC未观察到膜污染效应。

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.