Song Xiaosan, Yan Hairong, Shen Qingchao, Sun Wenjing, Li Ping, Wei Wenxuan
School of Environmental and Municipal Engineering, Lanzhou Jiaotong University Lanzhou 730070 China
Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University No. 88 Anning West Road Lanzhou 730070 China.
RSC Adv. 2025 May 27;15(22):17476-17490. doi: 10.1039/d5ra01783a. eCollection 2025 May 21.
In this study, the effects of the coagulant type, compounding ratio, dosage, hydraulic conditions and water temperature on the intensive coagulation process were systematically investigated for the treatment of discharge water with high turbidity and high sediment characteristics from a Yellow River water purification plant (YRWPP). Results indicated that the PFS-PDMDAAC composite coagulant achieved optimal treatment performance under the following conditions: a blending ratio of 6 : 1, a dosage of 13.65 mg L, rapid mixing at 300 rpm for 1.5 min, slow mixing at 120 rpm for 7 min, and a water temperature of 20 °C. Employing these parameters, supernatant turbidity was reduced to 46.2 NTU, the specific resistance to filtration (SRF) of the sludge was less than 0.94 × 10 m kg, and the solid content exceeded 8%, enabling direct dewatering. With the increase of the concentration of the discharged mud water, the effect of enhanced coagulation is weakened. Specifically, when the concentration was lower than 4.14%, a dosage of 13.65 mg L could be treated effectively; when the concentration was in the range of 4.14-9.12%, the dosage needed to be increased to 21 mg L; and when the concentration was more than 9.12%, it was difficult to achieve the discharge standard. Furthermore, zeta potential analysis showed that the absolute zeta potential value was the lowest when the compounding ratio was 6 : 1, and the effect of colloid destabilization was the best. According to floc morphology observation, the volume of floc increased and the structure of floc was loose and porous after enhanced coagulation, which was conducive to settling and dewatering. The analysis of the floc particle size showed that the average floc particle size increased from 38.3 μm to 238 μm at a dosage of 21 mg L, and the settling performance was significantly improved; when the dosage was more than 21 mg L, the floc particle size decreased, and the settling performance declined. This study provides technical support for the treatment and resource utilization of mud water discharged from the Yellow River water purification plant.
本研究针对黄河净水厂具有高浊高泥沙特性的排水处理，系统地研究了混凝剂类型、复配比例、投加量、水力条件及水温对强化混凝过程的影响。结果表明，在以下条件下，聚合硫酸铁-二甲基二烯丙基氯化铵（PFS-PDMDAAC）复合混凝剂实现了最佳处理性能：复配比例为6∶1，投加量为13.65 mg/L，快速搅拌转速300 rpm持续1.5 min，慢速搅拌转速120 rpm持续7 min，水温20℃。采用这些参数时，上清液浊度降至46.2 NTU，污泥的比过滤阻力（SRF）小于0.94×10 m/kg，且固体含量超过8%，可直接脱水。随着排泥水浓度的增加，强化混凝效果减弱。具体而言，当浓度低于4.14%时，13.65 mg/L的投加量可有效处理；当浓度在4.14%至9.12%范围内时，投加量需增至21 mg/L；而当浓度超过9.12%时，难以达到排放标准。此外，ζ电位分析表明，复配比例为6∶1时绝对ζ电位值最低，胶体失稳效果最佳。根据絮体形态观察，强化混凝后絮体体积增大，结构松散且多孔，有利于沉降和脱水。絮体粒径分析表明，投加量为21 mg/L时，絮体平均粒径从38.3 μm增至238 μm，沉降性能显著改善；当投加量超过21 mg/L时，絮体粒径减小，沉降性能下降。本研究为黄河净水厂排泥水的处理及资源利用提供了技术支持。
