ABSTRACT

Most of nitrogen emissions can be ascribed to agro-industrial activities. Since digestate produced by fermentation of agro-industrial residues can be difficult to dispose of due to its high ammonium content, advanced technical- and cost-effective technologies must be developed and applied in order to significantly reduce its impact on the environment. In this study, aerobic granules were successfully cultivated in a granular sludge sequencing batch reactor (GSBR) fed with the ammonium-rich (approx. 2500 mg L⁻¹) effluent of a 3-stage anaerobic digester treating agro-industrial residues. The peculiar characteristics of such wastewater required a 2-step operating strategy aimed at the selection of nitrifying biomass (Step 1) and the formation of aerobic granular sludge (Step 2). During Step 1, nitrifying biomass selection was achieved by properly regulating the cycle length: ${\mathrm{N}\mathrm{H}}_4^{+}\text{-}\mathrm{N}$ removal rates progressively increased from 42 to 109 mg_N L⁻¹d⁻¹, and a corresponding increase in ${\mathrm{N}\mathrm{H}}_4^{+}\text{-}\mathrm{N}$ specific removal rates from 8 to 24 mg_N g_VSS⁻¹d⁻¹ was also observed. During Step 2, the increase in selective pressures (i.e. minimum settling velocity and volumetric organic loading rate) led to the formation of compact (average diameter, 1.02 ± 0.43 mm) and well-settling granules (SVI₅, 28.6 ± 3.8 mL g_TSS⁻¹), which were able to remove up to 89 ± 2% of organic matter (as COD), 79 ± 3% of ${\mathrm{N}\mathrm{H}}_4^{+}\text{-}\mathrm{N}$ and 59 ± 4% of nitrogen (as a sum of ${\mathrm{N}\mathrm{H}}_4^{+}\text{-}\mathrm{N}$, ${\mathrm{N}\mathrm{O}}_2^{\text{–}}\text{-}\mathrm{N}$ and ${\mathrm{N}\mathrm{O}}_3^{\text{–}}\text{-}\mathrm{N}$). The 2-step operating strategy played a key role in biomass selection and subsequent granule formation and maintenance in the GSBR, and may be successfully adopted for the treatment of different ammonium-rich wastewaters.

摘要

大多数氮排放可归因于农工业活动。由于农业工业残留物发酵产生的消化物由于铵含量高而难以处理，因此必须开发和应用先进的技术和具有成本效益的技术，以显着减少其对环境的影响。在这项研究中，好氧颗粒在颗粒污泥序批式反应器 (GSBR) 中成功培养，其中加入了富含铵（约 2500 mg L ^-1) 处理农业工业残留物的 3 级厌氧消化器的流出物。这种废水的特殊特性需要一个两步操作策略，旨在选择硝化生物质（步骤 1）和好氧颗粒污泥的形成（步骤 2）。在步骤 1 中，通过适当调节循环长度来实现硝化生物质选择：${\mathrm{N}\mathrm{H}}_4^{+}\text{——}\mathrm{N}$去除率从 42 mg _N L ^-1 d ^-1逐渐增加到 109 mg _N L ^-1 d ^-1，并相应增加${\mathrm{N}\mathrm{H}}_4^{+}\text{——}\mathrm{N}$还观察到从 8 到 24 mg _N g _VSS ^-1 d ^{-1 的}特定去除率。在步骤2期间，增加的选择压力导致紧凑的形成（即，最小建立速度和体积有机负荷率）（平均直径，1.02±0.43毫米），以及沉降的颗粒（SVI ₅，28.6±3.8毫升克_TSS ⁻¹ )，能够去除高达 89 ± 2% 的有机物（作为 COD），79 ± 3%${\mathrm{N}\mathrm{H}}_4^{+}\text{——}\mathrm{N}$ 和 59 ± 4% 的氮（作为总和 ${\mathrm{N}\mathrm{H}}_4^{+}\text{——}\mathrm{N}$, ${\mathrm{N}\mathrm{哦}}_2^{\text{——}}\text{——}\mathrm{N}$ 和 ${\mathrm{N}\mathrm{哦}}_3^{\text{——}}\text{——}\mathrm{N}$）。两步操作策略在 GSBR 中的生物质选择和随后的颗粒形成和维护中发挥了关键作用，可成功用于处理不同的富铵废水。