Removal of pharmaceuticals by powdered activated carbon adsorption: Effect of particle size and point of addition

摘要

Endocrine disrupting chemicals, anti-microbial compounds, and other pharmaceuticallyrnactive compounds, are ubiquitous in wastewater treatment plant effluents and in drinkingrnwater sources that are impacted by wastewater discharges. Powdered activated carbon (PAC)rnadsorption is one water treatment process that can effectively remove pharmaceuticals, butrnlittle information is available on factors that affect pharmaceutical removal by PAC.rnObjectives of this research were to evaluate 1) the effectiveness of different PAC types (coalrnbased, wood based, lignite based) for pharmaceutical removal; 2) the effect of PAC particlernsize (as-received PAC and submicrometer-sized PAC or S-PAC) on pharmaceutical uptakernrates; 3) the effect of solution pH on pharmaceutical removal; 4) the effect of coagulantrnaddition on PAC effectiveness; 5) the effect of different PAC addition points onrnpharmaceutical removal. Batch kinetic tests and jar tests were completed with sixrnpharmaceuticals [bezafibrate (BZF), diclofenac (DCF), ibuprofen (IBP), metoclopramidern(MCP), sulfamethoxazole (SMX), trimethoprim (TMP)]. Removal of the weak acid SMXrnincreased with decreasing pH and removal of the weak base TMP increased with increasingrnpH. Pharmaceutical uptake rates obtained with S-PAC were considerably faster than thosernobtained with as-received PAC. Timing of PAC addition affected pharmaceutical removal andrnfinished water turbidity. The presence of aluminum hydroxide floc interfered with TMPrnremoval, especially when PAC was added together with coagulant. When PAC was addedrnduring the flocculation stage, settled water turbidity was higher than when PAC was addedrneither prior to or together with alum.