Solar photocatalytic treatment of greywater, collected from a residential apartment, was performed in the study using nitrogen-doped TiO₂ (NP-TiO₂) coated on gravels. XRD pattern displayed dominance of the anatase phase of NP-TiO₂. Morphological analysis by SEM images indicated the improved porous structure of NP-TiO₂ with an average particle size of 109.11 nm with a size range of 91–120 nm. Elemental analysis confirmed the formation of NP-TiO₂ by the doping of N into the P-25 structure, and UV–visible spectroscopy results showed improvement in visible light absorption. The efficacy of greywater treatment was evaluated in terms of the degradation of organics, nutrients, surfactants and benzophenone (BP). Solar photocatalytic degradation resulted in significant removal of organics (total organic carbon, TOC removal of 93.7%), with a degradation rate of 0.393 h⁻¹. A maximum of 50% TKN removal efficiency was achieved with photocatalytic oxidation to nitrate. Furthermore, the nitrate removal efficiency of 43% was observed due to the photocatalytic reduction. The maximum removal efficiency of phosphate, surfactant and BP was 55, 75, and 98.5%, respectively. Besides, toxicity in terms of bioluminescence inhibition (for 30 min incubation) showed a reduction from 13.6 to 4% for the treated greywater. The non-specific hydroxyl radical attack, demethylation, and bond cleavage between the carbonyl group and benzene ring carrying hydroxyl and methoxy groups were the dominant mechanism of BP degradation. The catalyst reusability test showed ~0.7% and ~1.5% decrease in TOC and BP removal efficiencies, respectively, after three consecutive cycles.

在研究中，使用涂在砾石上的氮掺杂TiO ₂（NP-TiO ₂）对从住宅公寓收集的灰水进行了太阳能光催化处理。XRD图谱显示出NP-TiO ₂的锐钛矿相占优势。SEM图像的形态分析表明，NP-TiO _2的多孔结构得到改善，平均粒径为109.11 nm，粒径范围为91–120 nm。元素分析证实了NP-TiO ₂的形成通过将N掺杂到P-25结构中，紫外可见光谱结果显示可见光吸收有所改善。根据有机物，营养物，表面活性剂和二苯甲酮（BP）的降解情况评估了灰水处理的功效。太阳光催化降解导致大量去除有机物（有机碳总量，TOC去除率为93.7％），降解速率为0.393 h ^-1。通过光催化氧化为硝酸盐，最大可去除TKN 50％。此外，由于光催化还原，观察到硝酸盐去除效率为43％。磷酸盐，表面活性剂和BP的最大去除率分别为55％，75％和98.5％。此外，就生物发光抑制（孵育30分钟）而言，处理后的灰水的毒性从13.6％降低至4％。BP降解的主要机理是非特异性羟基自由基的攻击，去甲基化以及羰基与带有羟基和甲氧基的苯环之间的键断裂。催化剂可重复使用性测试显示，在连续三个循环后，TOC和BP去除效率分别降低了约0.7％和约1.5％。