【作者】 周芳；

【导师】 夏素兰；

【作者基本信息】 四川大学 ， 化学工程， 2004， 硕士

【摘要】 钻井废水是石油与天然气开采与勘探过程中产生的污染物。钻井废水具有色度高、悬浮物浓度高、CODcr含量高、含有一定量的油的复杂性和多变性的水质特点,以及钻井作业的分散性和流动性的行业特点。针对该废水的特点和井场可实施的条件,本课题采用酸化-中和-混凝-氧化组合的处理方法,在较宽的水质范围进行了钻井废水处理的实验研究,探讨了以粉煤渣作吸附剂对废水作进一步处理的可行性,并对上述各处理过程的机理进行了分析。实验结果表明:⑴ 酸化可有效降低钻井废水的CODcr值和悬浮物含量,同时酸化有较好的破乳作用,pH值越低,反应速度越快,废水的悬浮物及油的脱除率越高,CODcr值和色度下降越大;酸化后的中和处理不会使酸化后的沉淀物重新分散,且中和剂的加入可进一步加深废水的处理。在本实验水质条件下,酸化pH值调至2时,废水的CODcr值由1086~10900 mg/l降至211~1399mg/l,脱除率为80.6~87.3%;悬浮物由1.8×103~2.3×104 mg/l降至30~579mg/l,脱除率为97.5~98.6%;色度由1.5×103~2.1×104倍降至50~600倍,脱除率为95.0~97.8%;油含量由71~680 mg/l降至13~150mg/l,脱除率为78.0~86.6%;中和pH值调至9时,上述指标均有一定的下降,CODcr值降至99～1267mg/l,脱除率为9.44~53.1%;悬浮物降至221mg/l以下,脱除率大于61.8%;色度降至10~350倍,脱除率为41.7~80.0%;油含量降至3~90mg/l,脱除率为40.0~76.9%。⑵ 对CODcr值及悬浮物含量较高的钻井废水,酸化-中和处理是非常必要的,处理后废水的粘度下降,有利于后续的混凝处理,且混凝处理剂用量也可大大减少,混凝<WP=3>效果有显著提高。⑶ 混凝处理可与酸化-中和在同一池中进行,通过筛选实验得出,PFS与PAC均是较理想的钻井废水混凝处理剂,在适当的工艺条件和加量下可大幅降低钻井废水的CODcr、色度及悬浮物含量。当钻井废水含渣率小于6%时,可不使用助凝剂PAM,在沉降池中停留时间应为15~20min;含渣率在10%左右的废水需用助凝剂PAM加速悬浮物的沉降,停留时间应在20~25min以上;含渣率在15%以上的钻井废水应采用离心机进行分离。⑷ 对混凝处理后尚未达标的上清液,采用Fenton试剂催化氧化可有效降低其CODcr值。当所取上清水样的CODcr值为747mg/l时,在H2O2/Fe2+摩尔比为8.7:1,加量分别为1.6ml/l和0.5g/l下,氧化3h后,CODcr的去除率为54%。⑸ 静态实验测得所取粉煤渣对CODcr的吸附容量为8.3mg/g。对CODcr值为341mg/l的Fenton氧化处理后的上清水样的吸附实验结果显示,要满足达标排水,粉煤渣的用量为25g/l。⑹ CaO具有较好的破乳作用。当CaO加量大于1.0 g/l时,漂浮油层明显增加即油的脱除率增加,且CaO与PAC和PFS凝聚破乳具有协同增效作用。依据实验研究结果,本文提出了可随原水水质和出水要求而进行组合的处理技术方案,给出了各过程的主要工艺控制参数。在研究基础上,初步完成了钻井废水井场处理装置的工艺流程设计及主要设备的工艺设计,这对钻井废水的井场处理有着实际的应用意义。更多还原

【Abstract】 The drilling wastewater is one of the main pollutants produced in Oil & Gas drilling fields. It has the water quality characteristics of changeability and complexity of component, and it also has the characteristics of dispersing and movability of drilling operation. Usually its CODcr, chroma and suspended solids are higher than those regulated in standard, and it also contains oil component. According to the characteristics of the drilling wastewater and the implementary conditions in the well, experimental studies on drilling wastewater treatment have been made by a combined method of acidification, neutralization, coagulation and oxidation under various conditions, then the feasibility of the further treatment with cinder used as adsorption has been discussed, and the mechanism of the major process have also been studied.Experimental results show: ⑴Acidification can reduce the CODcr value and the content of suspended solids, and it also can play a good role in demulsification. Neutralization can improve the treatment. Under the experimental conditions, when pH is been adjusted to 2, its CODcr value has been reduced from 1086~10900 mg/l to 211~1399mg/l, whose removal rate is 80.6~87.3%, its content of suspended solids has been reduced from 1.8×103~2.3×104 mg/l to 30~579mg/l with the removal rate of 97.5~98.6%, And the chroma and oil elimination is 95.0~97.8% and 78.0~86.6% respectively. When pH is adjusted to 9, its CODcr value has been lowered by 99～1267mg/l. The oil elimination is 41.7~80.0%. And over 61.8% suspended solids and <WP=5>40.0~76.9% oil can be removed. ⑵The acidification and neutralization process is effective on the drilling wastewater treatment of high CODcr and suspended solids. And the viscosity has been decreased after the treatment, which helps to the coagulation. And the dosage of flocculants may be reduced greatly. ⑶Coagulation, acidification and neutralization can be done in the same tank. The selection of the flocculants indicates that PFS and PAC are both the perfect flocculants. The removal efficiency of suspended solids, CODcr, oil and chroma can be increased greatly following adequate technique conditions. The wastewater of sludge content <6% is mixed with proper amount of PAC only and the sedimentation proceeds in 15~20min, the wastewater of sludge content about 10% is mixed with PAC and PAM and sedimentates for 20~25min, and wastewater of sludge content 15% need be centrifuged. ⑷After coagulation treatment, those that can not come up to the national drainage standards have been oxidized by Fenton reagent. When the molar ratio of H2O2 and Fe2+ is 8.7:1,their dosage is 6ml/l and 0.5g/l, and the oxidation time reaches 3h, the CODcr removal rate can reach 54%. ⑸The adsorption capacity of cinder is 8.3mg/g in the statistic experiment. The adsorption experiment has showed that the dosage is 25g/l when the wastewater with original CODcr 341mg/l can meet the discharged criteria. ⑹CaO has good demulsification effect. When the dosage exceeds 1.0g/l, the oil removal is increased. And PAC, PFS and CaO have good synergism in coordination.Based on the results of the experimental research, a combined process that can change with the water quality and the requirements of the effluents has been proposed. And the major parameters are also provided. In the end, the elementary process design has been finished, which has practical applied meaning to the treatment of the drilling wastewater.更多还原