16s rRNA seqs - biochar amended activated sludge community

In this study, we investigated the effects of biochar amendment on nitrification in sequencing batch reactors seeded with activated sludge. Biochar-amended reactors exhibited improved nitrification and were enriched for AOB compared to control reactors, as determined via qPCR analysis.Six bench-scale (0.81L) air lift sequencing batch reactors (SBRs) were inoculated with activated sludge collected from the aerobic react stage of a full scale SBR at Brainerd Wastewater Treatment Facility in Brainerd, MN. Reactors operated on an 8-hour cycle consisting of 10 minutes settling, 7 min effluent removal, 5.75 min influent fill, and 7.62h aerobic react. Volumetric turnover in reactors was 50% per operational cycle.Reactors were fed a synthetic wastewater (SWW) influent made to target 200mg/L chemical oxygen demand (COD) and 35 mg N/L of ammonia, and amended with SL-10 Trace Elements.Duplicate SBRs (BC1, BC2) were each amended with 3 g biochar (particle sizes 0.5-2 mm). Two additional reactors (DX1, DX2) were amended with Supelite(TM) DAX-8, a granular polymethacrylate reverse phase resin material. DAX-8 has similar particle size and surface area properties as the biochar used in this study. Biochar particles mesh size 10-35 and DAX-8 particles mesh size 40-60. Biochar particles surface area 231 m2/g and DAX-8 particles surface area 140 m2/g. The addition of particles to reactors may aid in sludge retention via enhanced settleability and by providing additional surface area for microbial biofilm growth. Unlike biochar, DAX-8 was not found to substantially sorb ammonia. Thus, DAX-8 amended reactors are meant to control for the effects of increased surface area and enhanced settleability of biomass carriers on nitrification. DAX-8 reactors received 5 g of DAX-8 particles, which provided the same surface area as the 3g biochar provided to biochar reactors (695.4 m2/reactor). Two control reactors (C1, C2) were set up without addition of a carrier material and contained only activated sludge.The effects of biochar amendment on activated sludge microbial community was assessed by performing 16s rRNA amplicon sequencing analysis on samples from biochar amended, DAX-8 amended, and control reactors.

本研究探究了生物炭投加对以活性污泥（activated sludge）为接种污泥的序批式反应器（sequencing batch reactor, SBR）硝化作用的影响。经定量聚合酶链反应（qPCR）分析可知，相较于对照组反应器，投加生物炭的反应器硝化性能更佳，且氨氧化细菌（ammonia-oxidizing bacteria, AOB）丰度更高。本实验共设置6台台架规模（有效容积0.81L）的气提式序批式反应器，接种污泥取自美国明尼苏达州布雷纳德市布雷纳德污水处理厂全尺寸序批式反应器的好氧反应段。反应器运行周期为8小时，具体流程包括：10分钟静置沉降、7分钟排水、5.75分钟进水以及7.62小时好氧反应。每个运行周期的水体置换率为50%。反应器进水采用合成废水（synthetic wastewater, SWW），预设化学需氧量（chemical oxygen demand, COD）为200mg/L、氨氮浓度为35mg N/L，同时添加SL-10微量元素营养液。其中两组平行反应器（BC1、BC2）各投加3g粒径范围为0.5~2mm的生物炭。另外两组平行反应器（DX1、DX2）投加Supelite™ DAX-8，这是一种颗粒状聚甲基丙烯酸酯反相树脂材料。DAX-8的粒径与比表面积参数与本实验所用生物炭相近：生物炭粒径为10~35目，DAX-8粒径为40~60目；生物炭比表面积为231 m²/g，DAX-8比表面积为140 m²/g。向反应器中投加颗粒载体可通过提升污泥沉降性能、为微生物生物膜生长提供额外附着表面积，从而辅助污泥截留。与生物炭不同，未发现DAX-8可显著吸附氨氮。因此，投加DAX-8的反应器用于控制载体比表面积提升与污泥沉降性能改善对硝化作用的影响。DAX-8反应器投加5g该树脂颗粒，使其总比表面积与投加3g生物炭的生物炭反应器一致（695.4 m²/反应器）。另外设置两组空白对照组（C1、C2），仅接种活性污泥，未投加任何载体材料。本研究通过对投加生物炭反应器、投加DAX-8反应器以及对照组反应器的样品进行16S rRNA扩增子测序分析，评估了生物炭投加对活性污泥微生物群落的影响。