School of Civil Engineering, Chang'an University, Xi'an 710054, China E-mail:
PetroChina Changqing Oilfield Company Associated Gas Comprehensive Utilization Project Department, Xi'an 710018, China.
Water Sci Technol. 2021 Mar;83(5):1108-1117. doi: 10.2166/wst.2021.054.
It is difficult to adjust the pH of oil acidized wastewater rich in Ca, thus hindering the polyacrylamide (PAM) flocculation. This study aims at accelerating the flocculation process by introducing CO into the water to induce the formation of CaCO nuclei. The order in which CO and NaOH were added affected the floc structures. Compared with CO-NaOH-PAM, the flocs of NaOH-CO-PAM were more compact and more CaCO crystals were formed. The aqueous Ca involved in the reaction reached 20%, and CO utilization was enhanced. The settling time was shortened by half (from 20 to 3 min), and NaOH consumption was reduced by one-tenth (from 0.03 to 0.003 mol), hence significantly reducing the costs. Due to the higher settling rate and shorter contact time, the NaOH-CO-PAM flocs adsorbed less so that the residual oil was 124 mg·L, while in the case of CO-NaOH-PAM it was 88 mg·L. As a promising coagulation aid, CO can also be used to mineralize pollutants in wastewater.
酸化油废水富含 Ca，其 pH 值难以调节，从而阻碍了聚丙烯酰胺（PAM）的絮凝。本研究旨在通过向水中引入 CO 来诱导 CaCO3 核的形成，从而加速絮凝过程。CO 和 NaOH 的加入顺序影响絮体结构。与 CO-NaOH-PAM 相比，NaOH-CO-PAM 的絮体更致密，形成更多的 CaCO3 晶体。参与反应的水中 Ca 含量达到 20%，CO 的利用率提高。沉降时间缩短了一半（从 20 分钟缩短至 3 分钟），NaOH 消耗减少了十分之一（从 0.03 摩尔减少至 0.003 摩尔），从而显著降低了成本。由于沉降速率更高且接触时间更短，NaOH-CO-PAM 絮体吸附的油更少，残留油为 124mg·L，而 CO-NaOH-PAM 的残留油为 88mg·L。作为一种很有前途的混凝助剂，CO 还可以用于矿化废水中的污染物。
