Technische Universität Darmstadt, Fachgebiet Abwassertechnik, 64287 Darmstadt, Germany.
Water Sci Technol. 2010;61(5):1173-81. doi: 10.2166/wst.2010.059.
Water reuse for agricultural irrigation can contribute to the conservation of valuable water resources and opens the possibility to reuse the wastewater's nutrients (N and P) at the same time. As irrigation is usually limited to vegetation periods, effluent requirements for treated wastewater may vary seasonally. A process concept for wastewater treatment with variable operation modes for the seasonal production of nutrient-rich irrigation water and nutrient-poor discharge water is proposed. It is shown that a two-step process consisting of organics removal followed by biological aerated filters (biofilters) for nitrogen removal is a promising combination which allows a flexible and seasonally varied operation with a fast re-start of biological nitrification after shut-down periods. To date, there is no commonly accepted practice amongst operators to take biofilters out of service for periods of time while - at the same time - maintaining biological activity to enable a quick start-up. This paper shows that during shut-down periods the activity drop rate is the smallest if the filter bed is maintained flooded and without aeration; then a very quick re-start is possible.
农业灌溉的水再利用有助于节约宝贵的水资源，并为同时再利用废水的养分（N 和 P）开辟了可能性。由于灌溉通常仅限于植被期，因此处理后的废水的排放要求可能会随季节而变化。提出了一种具有可变操作模式的废水处理工艺概念，用于季节性生产富营养灌溉水和贫营养排放水。结果表明，由有机物去除和随后的生物曝气滤池（生物滤池）进行氮去除的两步工艺是一种很有前途的组合，可实现灵活的季节性操作，并可在停机后快速重新开始生物硝化。迄今为止，操作人员没有普遍接受的做法，即在不停止生物活性的情况下将生物滤池停机一段时间，以实现快速启动。本文表明，如果滤床保持充满水且不曝气，则在停机期间，滤床的活性下降率最小；然后可以快速重新启动。
