基于互联网大数据的成都餐饮源细颗粒物排放空间分配研究

餐饮过程排放的废气正成为大城市大气污染的重要来源之一.根据成都市2013年排放清单更新的研究成果,综合运用本地化的餐饮排放因子、排放活动水平的调查成果和成都市统计年鉴的统计数据等信息,对成都市餐饮源的PM_(2.5)排放总量进行了估算,其结果为4740 t·a~(-1).为了对区域的餐饮废气排放进行空间分配,本文抓取了互联网兴趣点POI信息.通过这些信息,对成都市的社会餐饮、学校食堂餐饮和家庭餐饮的空间来源进行了表征,对成都市生活源中餐饮污染物排放的空间分布规律进行了探索,并提出了新的餐饮源高分辨空间分配方法.结果表明,基于POI空间分配的2013年成都餐饮源单位面积年排放强度均值为0.29 t·km~(-2)·a~(-1),主城区均值为3.47 t·km~(-2)·a~(-1),全市的排放量分布区间为0~35.7 t·km~(-2)·a~(-1).互联网POI信息可以作为研究城市餐饮源空间分布的重要数据来源,在实际应用上更适于表征社会餐饮点源污染.     

成都市道路移动源减排对空气质量的短期影响

近年来随着经济社会的高速发展,我国的空气污染问题日渐突出.管控污染源以减少污染物排放是改善空气质量的主要手段,且其效率如何会极大地影响空气质量的改善效果.但通常情况下,单一减排手段的实施对空气质量的改善的实际贡献往往在短时间内较难做出客观评价.本研究借助新冠疫情期间以道路移动源为主的各类污染源排放短期内大量下降的机会,通过疫情管控措施实施前后交通条件和空气质量的对比,分析道路移动源减排对空气质量改善的短期影响.结果表明,实施管控措施后,城市范围内道路交通条件明显改善,拥堵路段基本消失.受此影响,各类主要污染物浓度出现不同程度的下降,其中,受道路移动源贡献较大的NO₂浓度下降比例达40%~60%,PM_2.5因受气象条件影响较大而下降幅度较小.结合实时的交通数据估算其相应的尾气排放结果表明,疫情期间道路移动源排放的NO_x、HC、CO分别下降59.7%、59.9%和58.8%.本研究对于分析短时间内急速减排等应急措施对环境改善的效果,以及削减污染物排放对空气质量改善的潜力有重要的实际参考价值.     

2015年中国地区大气甲烷排放估计及空间分布

CH₄是仅次于CO₂的重要温室气体,也是重要的化学活性气体.定量估算我国甲烷的排放量及分析其空间分布特征,对于控制温室气体排放,减缓温室效应具有重要意义.本文以2015年中国官方统计年鉴资料为基础,利用IPCC排放清单指南、国内外排放因子研究结果及动力学模型方法,从能源活动（煤炭开采和油气系统）、农业活动（反刍动物、稻田排放和秸秆露天燃烧）、自然源排放（自然湿地和植被排放）、废弃物处理（固体废弃物、工业污水和生活污水）和人工湿地等几个主要方面,对中国地区的CH₄排放进行定量估计.结果表明：中国地区2015年CH₄排放总量为61.59 Tg,其中以农业活动和能源活动为主要排放源,排放量分别达到20.42 Tg和20.39 Tg,占总排放量比例分别约为33.2%和33.1%.CH₄自然源考虑了植被和自然湿地排放,排放量为11.77 Tg,占比为19.1%;废弃物处理产生的CH₄排放量为8.64 Tg,占比为14.0%;人工湿地排放量为0.37 Tg,占比为0.6%.从空间分布来看,CH₄排放具有较明显的不均匀性,大值区主要集中在华北、西南及东南地区,而西北地区的排放量则相对较低,主要与各地的资源环境、人口密度和经济情况密切相关.     

中国农业机械的使用特征及其尾气排放的时空分布

我国农业机械保有量巨大且其尾气排放不容忽视.了解其使用特征、分析其尾气排放的时空分布,对提高非道路机械尾气排放清单准确性、制定减排政策具有重要意义.本研究通过实际调研获取我国农业机械的活动水平,并在此基础上分析其活动水平与机械类型、车龄、分布地区之间的关系,以此量化其使用特征;使用BP神经网络的方法预测我国2020—2025年农业机械保有量,结合调研的活动水平和收集的排放因子数据,估算我国2020—2025年农业机械尾气污染物排放清单;基于各省份农业机械保有量、活动水平的差异,探讨我国农业机械尾气排放的空间分布.研究结果表明：①我国农业机械的使用因机械类型、车龄、分布地区等因素的影响存在较大的变化性.农业机械的年均工作时间可在217~1721 h·a^-1之间变化,单台机械年均耗油量可在0.2~10.5 t·a^-1之间变化.②据本研究预测,2020年后,我国农业机械保有量将持续增长,受排放标准提升、老旧机械淘汰等减排措施的影响,其尾气排放呈下降趋势,到2025年,农业机械CO、HC、NO_x和PM_2.5排放将比2020年下降0.1%~26.2%.③与地区的农业机械保有量密切相关,河南、山东、安徽的农业机械尾气排放量最大.与春季相比,秋季各省份农业机械尾气排放更为显著.     

基于遥感资料的中国东部地区植被VOCs排放强度研究

本研究充分基于遥感资料获取中国东部地区叶面积指数和叶生物量的最新信息,并广泛调研了植被VOCs排放因子的最新研究进展,以2008—2010年的植被和气象的平均状态为背景,基于MEGAN排放模型,研究了中国东部地区植被VOCs(BVOCs)排放的时空分布特征.结果表明,我国东部地区BVOCs年排放总量为11.3×106t(以C计,下同),其中异戊二烯(ISOP)、单萜烯(MON)和其它VOC(OVOC)质量分数(下同),分别为44.9%、31.5%、23.6%.BVOCs排放呈现明显的季节变化特征,春、夏、秋、冬4个季节分别占全年的11.2%、71.8%、14.1%和3.0%.空间分布上,排放高值区主要分布于大小兴安岭、长白山脉、秦岭大巴山脉、东南丘陵、海南等植被茂密的区域,年均排放强度一般在1500～6000kg·km-·2a-1之间,福建、广东、江西、浙江、湖南、湖北等省份BVOCs的排放总量与平均排放强度均较高.本研究所得到的高时空分辨率的BVOCs排放清单,可以为区域环境与气候的数值模拟研究提供基础.     

阳泉市2017年基于交通流量的机动车排放清单

通过van Aerde速度-流量模型模拟和交通流量调查获取了阳泉市路网的车流量、车型构成和车速基础数据,利用自下而上的方法,基于实际交通流量数据、机动车排放因子和路段,构建了阳泉市道路机动车排放清单,并分析了机动车污染物排放特征。结果表明:2017年阳泉市道路机动车排放的CO、HC、NO_x、PM分别为4.56×10⁴、0.96×10⁴、1.76×10⁴、0.024×10⁴ t。按道路类型划分,高速公路(含城市快速路)机动车污染物排放量较大,CO、HC、NO_x、PM排放量分别占排放总量的48.4%、48.9%、40.0%和34.3%;按车辆类型划分,小型客车是CO、HC排放的主要贡献者,重型货车是NO_x、PM排放的主要贡献者;按排放阶段划分,国4机动车排放的CO和HC占比较高,国3机动车排放的NO_x和PM占比较高;按区县划分,污染物排放量最大的为盂县,其次是平定县和郊区。机动车在道路上的实际排放量与道路类型、道路所属行政区域及车辆类型密切相关。     

Comprehensive evaluation method of urban air quality statistics based on environmental monitoring data and its application

Air quality monitoring is effective for timely understanding of the current air quality status of a region or city. Currently, the huge volume of environmental monitoring data, which has reasonable real-time performance, provides strong support for in-depth analysis of air pollution characteristics and causes. However, in the era of big data, to meet current demands for fine management of the atmospheric environment, it is important to explore the characteristics and causes of air pollution from multiple aspects for comprehensive and scientific evaluation of air quality. This study reviewed and summarized air quality evaluation methods on the basis of environmental monitoring data statistics during the 13th Five-Year Plan period, and evaluated the level of air pollution in the Beijing–Tianjin–Hebei region and its surrounding areas (i.e., the “2+26” region) during the period of the three-year action plan to fight air pollution. We suggest that air quality should be comprehensively, deeply, and scientifically evaluated from the aspects of air pollution characteristics, causes, and influences of meteorological conditions and anthropogenic emissions. It is also suggested that a three-year moving average be introduced as one of the evaluation indexes of long-term change of pollutants. Additionally, both temporal and spatial differences should be considered when removing confounding meteorological factors.     

Data quality evaluation and calibration of on-road remote sensing systems based on exhaust plumes

In recent years, with rapid increases in the number of vehicles in China, the contribution of vehicle exhaust emissions to air pollution has become increasingly prominent. To achieve the precise control of emissions, on-road remote sensing (RS) technology has been developed and applied for law enforcement and supervision. However, data quality is still an existing issue affecting the development and application of RS. In this study, the RS data from a cross-road RS system used at a single site (from 2012 to 2015) were collected, the data screening process was reviewed, the issues with data quality were summarized, a new method of data screening and calibration was proposed, and the effectiveness of the improved data quality control methods was finally evaluated. The results showed that this method reduces the skewness and kurtosis of the data distribution by up to nearly 67%, which restores the actual characteristics of exhaust diffusion and is conducive to the identification of actual clean and high-emission vehicles. The annual variability of emission factors of nitric oxide decreases by 60% – on average – eliminating the annual drift of fleet emissions and improving data reliability.     

昆明市高速公路机动车温室气体排放清单及时空性分布特征

为研究昆明市高速公路机动车的CO、CO₂、N₂O、CH₄温室气体排放清单,使用2021年昆明市高速公路客车交通流量数据、机动车GPS信息数据获得了高速公路网上的车型构成、车流量等基础数据,应用本土化修正后MOVES模型计算了昆明市高速公路的机动车CO、CO₂、N₂O、CH₄排放因子。基于实际交通流量数据、温室气体排放因子和昆明市高速公路实际道路信息,构建了昆明市高速公路机动车温室气体排放清单,并对其排放特征以及空间分布特征进行分析。结果表明：昆明市2021年高速公路机动车CO、CO₂、N₂O和CH₄的排放量分别为20 337.1、2 575 677.1、33.8和72.9 t,总计CO₂当量为2 626 212.5 t。按排放标准划分,国Ⅳ排放标准的机动车是4种温室气体排放的主要贡献车型;按车辆类型划分,小型客车是CO、CO₂、N₂O排放的主要贡献车型,大型客车是CH₄排放的主要贡献车型;按燃料类型划分,汽油车是CO、CO₂、N₂O的主要贡献车型,柴油车是CH₄排放的主要贡献车型。昆明市高速公路机动车温室气体排放时间分布特征为排放强度与不同时间段的交通流量呈正相关,在24 h内呈现双高峰变化;空间分布特征为排放强度与路网密度和区域交通流量密切相关,路网密度较高和交通流量较高的区域排放强度较高。

     

Significant influences of TiO2 crystal structures on NO2 and HONO emissions from the nitrates photolysis

The emissions of NO₂ and HONO from the KNO₃ photolysis in the presence of TiO₂ were measured using a round-shape reactor coupled to a NO_x analyzer. TiO₂ played important roles in the emission flux density of NO₂ (R_NO2) and HONO (R_HONO), depending on crystal structures and mass ratios of TiO₂. R_NO2 and R_HONO significantly decreased with increasing the rutile and anatase mass ratios from 0 to 8 and 0.5 wt.%, respectively. Nevertheless, with further increasing the anatase mass ratio to 8 wt.%, there was an increase in R_NO2 and R_HONO. R_NO2 on KNO₃/TiO₂/SiO₂ had positive correlation with the KNO₃ mass (1–20 wt.%), irradiation intensity (80–400 W/m²) and temperature (278–308 K), while it had the maximum value at the relative humidity (RH) of 55%. R_HONO on KNO₃/TiO₂/SiO₂ slightly varied with the KNO₃ mass and temperature, whereas it increased with the irradiation intensity and RH. In addition, the mechanism for NO₂ and HONO emissions from the nitrates photolysis and atmospheric implications were discussed.     

基于遥感数据的秸秆焚烧源排放清单及时空分布特征

分析秸秆焚烧事件引起的空气污染状况,常使用CMAQ、NAQPMS、WRF-CHEM等模型进行空气质量模拟,而污染源排放清单是模拟模型的关键输入.为满足模型清单输入要求,以2014年5月7日四川盆地内发生的一次由油菜秸秆焚烧引起的重污染事件为例,采用排放因子法进行污染物年排放量估算,结合卫星火点数据、土地利用数据对其进行空间特征分析,并使用Bluesky CONSUME模型估算了污染物的烟羽抬升,结合激光雷达获取了气溶胶消光系数以分析其时间特征.结果表明:以2013年为基准年,全年区域内CO、NO_x、SO₂、PM_2.5、PM₁₀及NMVOC（非甲烷挥发性有机化合物）的年排放量分别为5 791.022、193.842、43.268、574.602、1 495.350和1 495.350 t,成都市、德阳市、绵阳市、眉山市、资阳市各污染物排放量占比分别为13.90%、22.39%、31.81%、12.11%、19.79%.各污染物排放量均在地面层呈3个大值中心、2个空值带的分布趋势.采用环境1B卫星和MODIS火点数据结合提取焚烧火点分析发现,5月7日四川盆地内5个城市均存在不同程度的秸秆焚烧情况.经空间分配后发现,此次排放的重点在德阳市及绵阳市南部,污染物排放量最大值出现在德阳市中部,成都市秸秆焚烧火点最少,污染物排放量也最小.受当天大气边界层高度的影响,污染物垂直分布主要集中在35 m以下,并在30 m左右形成污染物极大层.另外,受秸秆焚烧管制影响,在16:00-翌日04:00排放量呈逐渐上升趋势,09:00-16:00排放量较少.研究显示,秸秆焚烧源排放清单与前人研究结果较为一致,排放清单的烟羽抬升结果与气溶胶消光系数的垂直分布较为吻合.      

Origins of black carbon from anthropogenic emissions and open biomass burning transported to Xishuangbanna, Southwest China

Black carbon (BC) has importance regarding aerosol composition, radiative balance, and human exposure. This study adopted a backward-trajectory approach to quantify the origins of BC from anthropogenic emissions ($\mathrm{B}{\mathrm{C}}_{\text{An}}$) and open biomass burning ($\mathrm{B}{\mathrm{C}}_{\text{BB}}$) transported to Xishuangbanna in 2017. Haze months, between haze and clean months, and clean months in Xishuangbanna were defined according to daily PM_2.5 concentrations of >75, 35–75, and <35 µg/m³, respectively. Results showed that the transport efficiency density (TED) of BC transported to Xishuangbanna was controlled by the prevailing winds in different seasons. The yearly contributions to the effective emission intensity of $\mathrm{B}{\mathrm{C}}_{\text{An}}$ and $\mathrm{B}{\mathrm{C}}_{\text{BB}}$ transported to Xishuangbanna were 52% and 48%, respectively. However, when haze occurred in Xishuangbanna, the average $\mathrm{B}{\mathrm{C}}_{\text{An}}$ and $\mathrm{B}{\mathrm{C}}_{\text{BB}}$ contributions were 23% and 77%, respectively. This suggests that open biomass burning (BB) becomes the dominant source in haze months. Myanmar, India, and Laos were the dominant source regions of BC transported to Xishuangbanna during haze months, accounting for 59%, 18%, and 13% of the total, respectively. Furthermore, India was identified as the most important source regions of $\mathrm{B}{\mathrm{C}}_{\text{An}}$ transported to Xishuangbanna in haze months, accounting for 14%. The two countries making the greatest contributions to $\mathrm{B}{\mathrm{C}}_{\text{BB}}$ transported to Xishuangbanna were Myanmar and Laos in haze months, accounting for 55% and 13%, respectively. BC emissions from Xishuangbanna had minimal effects on the results of the present study. It is suggested that open BB in Myanmar and Laos, and anthropogenic emissions in India were responsible for poor air quality in Xishuangbanna.     

基于实际飞行数据的首都机场飞机发动机日排放清单估算方法研究

根据航班实际飞行数据估算机场飞机主发动机排放量,可以提升机场排放清单编制的准确度.基于北京首都机场某日运行数据和国内1326架次航班的机载飞行数据(QAR数据),研究了基于飞行数据的机场飞机主发动机排放清单制定方法.采用一阶近似3.0(FOA3.0)方法补充国际民航组织发动机排放数据库颗粒物基准排放指数,结合QAR数据,应用波音燃油流量法2(BFFM2)估算了实际飞行条件下污染物排放指数,编制了首都机场该日飞机主发动机排放清单,分析了首都机场航班排放特征.在此基础上,探讨了结合实际数据本地化的着陆和起飞循环,以期为机场飞机主发动机排放量的快速准确核算提供新的思路.结果发现,该日航班主发动机HC、CO、NO_x和PM_(2.5)排放量分别为933.9、10967.8、14703.5和85.5 kg,较标准LTO循环估算结果的偏差分别为15.6%、13.2%、-29.1%和-18.9%.NO_x排放主要集中在起飞和爬升阶段,占其排放总量的68.0%;HC和CO排放主要集中在滑行和慢车阶段,分别占其排放总量的90.0%和88.0%;PM_(2.5)在各飞行阶段的排放较为平均.对于单位LTO循环,航班滑行过程中平均排队等候(地速为零)时间为7.7 min,产生的HC、CO、NO_x和PM_(2.5)分别占总滑行阶段对应污染物排放量的26.3%、27.5%、25.7%和27.5%,这一部分排放量有望通过场面运行优化进一步控制.     

Turnover of dissolved organic carbon fuels nocturnal CO2 emissions from a headwater catchment reservoir, Southeastern China: Effects of ecosystem metabolism on source partitioning of CO2 emissions

Dam reservoirs in headwater catchments, as critical zones for their proximity to terrestrial sources, play important roles in dissolved organic carbon (DOC) cycling. However, the effects of ecosystem metabolism (EM) on DOC cycling are not well known. Here, in-situ diurnal and monthly observations were conducted to measure EM (including gross primary production (GPP), ecosystem respiration (ER) and heterotrophic respiration (HR)), DOC turnover and CO₂ emissions in a headwater catchment reservoir in Southeastern China in 2020. Our study showed the nocturnal CO₂ emission rate was about twice as high as in daytime, and was strongly driven by EM. The values for DOC turnover velocity ranged from 0.10 to 1.59 m/day, and the average DOC turnover rate was 0.13 day⁻¹, with the average removal efficiency of 12%. The contribution of respired DOC to daily CO₂ emissions ranged from 17% to 61%. The accumulated efficiencies were estimated to be 13% for the selected 15 reservoirs throughout the Changjiang River network, corresponding to about 0.34 Tg C/year of the respired DOC. The modified CO₂ flux was 0.75 Tg C/year, and respired DOC accounted for about 45% of total emitted CO₂ from the 15 larger reservoirs. Our research emphasizes the necessity of incorporating the effects of EM into studies of reservoir DOC removal and CO₂ emissions.     

Size distribution and chemical characteristics of particles from crop residue open burning in North China

Crop residue open burning is an important emission source of ambient particles in China. This study analyzed the particle emission characteristics of crop residue open burning through combustion experiments with a novel open combustion simulation device using three typical crop straws in north China (corn, wheat, and rice). Particle samples size ranging from 0.006–9.890 µm were collected by an Electrical Low Pressure Impactor plus, a high size-resolution instrument capable of dividing particles into 14 size stages. The size distributions of organic carbon (OC), elemental carbon (EC), water-soluble ions, and elements were analyzed, and source chemical profiles were constructed for PM_0.1, PM₁, PM_2.5, and PM₁₀. The number concentration of particles was concentrated in the Aiken nuclei mode (0.006–0.054 µm), accounting for 75% of the total number, whereas the mass concentration was concentrated in the accumulation mode (0.054–0.949 µm), accounting for 85.43% of the mass loading. OC, EC, Cl^?, and K(include total K and water-soluble K) were the major chemical components of the particles, whose mass percentage distributions differed from those of other components. These five main components exhibited a bell-shaped size distribution in the 0.006–9.890 µm range, whereas the other components exhibited a U-shaped distribution. Among the chemical profiles for PM_0.1–PM₁₀, OC was the most important component at 10–30%, followed by EC at 2%–8%. The proportions of K⁺, Cl^?, and K varied substantially in different experimental groups, ranging from 0–15%, and K⁺ and Cl^? were significantly correlated (r = 0.878, α = 0.000).     

A remote sensing system of vehicle emissions based on tunable diode laser technology

As being an effective real-time method of monitoring vehicle emissions on-road, a remote sensing system based on the tunable diode laser （TDL） technology was presented, and the key technologies were discussed. A field test in Guangzhou（Guangdong, China） was performed and was found that the factors, such as slope, instantaneous speed and acceleration, had significant influence on the detectable rate of the system. Based on the results, the proposal choice of testing site was presented.     

基于"3S"的南京市大气污染源清单网格化空间分配研究

基于GIS、RS、GPS集成技术,依据南京市10大类大气污染源排放和空间分布特征,采用合适的空间分配方法,根据各排放源的相关权重分配因子,构建了南京市2015年大气污染源排放清单1 km×1 km的网格化空间数据库,并基于GIS平台叠加显示形成了2015年南京市大气污染源1 km×1 km空间分布图.结果表明,此次空间分配结果与南京市GDP、路网、人口、农业等相关分布特征相互吻合,说明本研究网格化空间分配方法较为合理可靠,可满足后续空气质量模拟的需求.     

Protonated acetone ion chemical ionization time-of-flight mass spectrometry for real-time measurement of atmospheric ammonia

Ammonia (NH₃) is ubiquitous in the atmosphere, it can affect the formation of secondary aerosols and particulate matter, and cause soil eutrophication through sedimentation. Currently, the use of radioactive primary reagent ion source and the humidity interference on the sensitivity and stability are the two major issues faced by chemical ionization mass spectrometer (CIMS) in the analysis of atmospheric ammonia. In this work, a vacuum ultraviolet (VUV) Kr lamp was used to replace the radioactive source, and acetone was ionized under atmospheric pressure to obtain protonated acetone reagent ions to ionize ammonia. The ionization source is designed as a separated three-zone structure, and even 90 vol.% high-humidity samples can still be directly analyzed with a sensitivity of sub-ppbv. A signal normalization processing method was designed, and with this new method, the quantitative relative standard deviation (RSD) of the instrument was decreased from 17.5% to 9.1%, and the coefficient of determination was increased from 0.8340 to 0.9856. The humidity correction parameters of the instrument were calculated from different humidity, and the ammonia concentrations obtained under different humidity were converted to its concentration under zero humidity condition with these correction parameters. The analytical time for a single sample is only 60 sec, and the limit of detection (LOD) was 8.59 pptv (signal-to-noise ratio S/N = 3). The ambient measurement made in Qingdao, China, in January 2021 with this newly designed CIMS, showed that the concentration of ammonia ranged from 1 to 130 ppbv.     

Vertical aerosol data assimilation technology and application based on satellite and ground lidar: A review and outlook

Observations and numerical models are mainly used to investigate the spatiotemporal distribution and vertical structure characteristics of aerosols to understand aerosol pollution and its effects. However, the limitations of observations and the uncertainties of numerical models bias aerosol calculations and predictions. Data assimilation combines observations and numerical models to improve the accuracy of the initial, analytical fields of models and promote the development of atmospheric aerosol pollution research. Numerous studies have been conducted to integrate multi-source data, such as aerosol optical depth and aerosol extinction coefficient profile, into various chemical transport models using various data assimilation algorithms and have achieved good assimilation results. The definition of data assimilation and the main algorithms will be briefly presented, and the progress of aerosol assimilation according to two types of aerosol data, namely, aerosol optical depth and extinction coefficient, will be presented. The application of vertical aerosol data assimilation, as well as the future trends and challenges of aerosol data assimilation, will be further analysed.     

Influence of MBBR carrier geometrical properties and biofilm thickness restraint on biofilm properties, effluent particle size distribution, settling velocity distribution, and settling behaviour

The relatively poor settling characteristics of particles produced in moving bed biofilm reactor (MBBR) outline the importance of developing a fundamental understanding of the characterization and settleability of MBBR-produced solids. The influence of carrier geometric properties and different levels of biofilm thickness on biofilm characteristics, solids production, particle size distribution (PSD), and particle settling velocity distribution (PSVD) is evaluated in this study. The analytical ViCAs method is applied to the MBBR effluent to assess the distribution of particle settling velocities. This method is combined with microscopy imaging to relate particle size distribution to settling velocity. Three conventionally loaded MBBR systems are studied at a similar loading rate of 6.0 g/(m² •day) and with different carrier types. The AnoxK™ K5 carrier, a commonly used carrier, is compared to so-called thickness-restraint carriers, AnoxK™ Z-carriers that are newly designed carriers to limit the biofilm thickness. Moreover, two levels of biofilm thickness, 200 μm and 400 μm, are studied using AnoxK™ Z-200 and Z-400 carriers. Statistical analysis confirms that K5 carriers demonstrated a significantly different biofilm mass, thickness, and density, in addition to distinct trends in PSD and PSVD in comparison with Z-carriers. However, in comparison of thickness-restraint carriers, Z-200 carrier results did not vary significantly compared to the Z-400 carrier. The K5 carriers showed the lowest production of suspended solids (0.7 ± 0.3 g-TSS/day), thickest biofilm (281.1 ± 8.7 µm) and lowest biofilm density (65.0 ± 1.5 kg/m³). The K5 effluent solids also showed enhanced settling behaviour, consisting of larger particles with faster settling velocities.