Achieving mainstream nitrogen removal via the nitrite pathway (NH₄⁺ → NO₂⁻ → N₂) is highly beneficial for energy neutral/positive wastewater treatment. Our previous batch assays revealed that ultrasonic treatment can suppress nitrite-oxidizing bacteria (NOB) while enhancing the activity of ammonia-oxidizing bacteria (AOB). Based on this concept, this study investigated the feasibility of applying ultrasonication to achieve the nitrite pathway in mainstream wastewater treatment. Two lab-scale sequencing batch reactors were set-up in parallel and fed with real municipal wastewater. With 100% of the sludge treated every 12 h at a treatment energy input of 0.066 kJ per mg mixed liquor suspended solids, the nitrite pathway was rapidly (within two weeks) established in the experimental reactor with stable effluent nitrite accumulation ratio (NO₂⁻/(NO₂⁻ + NO₃⁻)) of above 80% and significantly decreased NOB population. In comparison, the control reactor always possessed the conventional nitrification and denitrification pathway. Economic analysis indicated that energy consumption is too high for practical applications. However, this technology may be used in conjunction with other technologies, whereby this ultrasonic treatment can be used infrequently (e.g. once every few months) when the nitrite pathway becomes unstable.

通过亚硝酸盐途径实现主流脱氮（NH ₄ ⁺  →NO ₂ ⁻  →N ₂）对于能量中性/正性废水处理非常有益。我们以前的批次分析表明，超声波处理可以抑制亚硝酸盐氧化细菌（NOB），同时增强氨氧化细菌（AOB）的活性。基于这一概念，本研究调查了在主流废水处理中应用超声处理实现亚硝酸盐途径的可行性。并行设置了两个实验室规模的测序批处理反应器，并向其中加入了实际的城市废水。与污泥的100％处理过的每12小时以0.066的处理能量输入千焦每毫克混合液悬浮固体，以稳定的流出物亚硝酸盐积累比（NO建立在实验反应器中的亚硝酸盐途径被快速（在两周内）₂ ^- /（NO ₂ ^- + NO ₃ ^- ））的80％以上，显著降低NOB人口。相比之下，对照反应器始终拥有常规的硝化和反硝化途径。经济分析表明，能源消耗对于实际应用而言太高了。然而，该技术可以与其他技术结合使用，从而当亚硝酸盐途径变得不稳定时，可以不频繁地（例如，每几个月一次）使用这种超声处理。