ABSTRACT

Biological wastewater treatment plants (WWTPs) produce large amounts of excess sludge. One approach to reduce sludge is treatment with ozone, which promotes sludge disintegration and solubilization. Here we report the first application of ultra-fine- and micro-bubble (UFB/MB) ozonation to sludge reduction in a full-scale WWTP. UFB/MB ozonation using a spiral liquid-type UFB generator was applied to concentrated excess sludge in the storage tank instead of to return sludge. At an ozone dose of 15 mgO₃ gSS^–1, a 92% reduction in sludge accumulation rate was achieved during a 237-day ozonation period with ozonation relative to a 100-day no ozonation period without ozonation. This reduction was larger than expected, and was partly due to a 20–30% greater average concentration of suspended solids in the influent during the no ozonation period. Addition of UFB/MB ozonation to the existing activated sludge process did not reduce the water quality in the effluent. We can conclude that UFB/MB ozonation for concentrated excess sludge in the storage tank using a spiral liquid-type UFB generator remarkably reduced the ozone dose required to sludge reduction by more than half of the reported conventional ozonation (30–150 mgO₃ gSS^–1) without the negative impact on effluent water quality.

摘要

生物废水处理厂（WWTP）会产生大量的剩余污泥。减少污泥的一种方法是用臭氧处理，这会促进污泥的分解和溶解。在这里，我们报告了超细微气泡（UFB / MB）臭氧化技术在大规模污水处理厂中减少污泥的首次应用。使用螺旋液体型UFB发生器进行UFB / MB臭氧化处理，以浓缩储罐中的多余污泥，而不是返回污泥。臭氧剂量为15 mgO ₃ gSS ^–1，与不进行臭氧处理的100天无臭氧处理相比，在进行臭氧处理的237天臭氧处理期间，污泥累积速率降低了92％。这种减少幅度大于预期，部分原因是在无臭氧处理期间，进水中悬浮固体的平均浓度增加了20％至30％。在现有的活性污泥工艺中添加UFB / MB臭氧处理并不会降低废水中的水质。我们可以得出结论，使用螺旋液体型UFB发生器对储罐中的浓缩过量污泥进行UFB / MB臭氧处理，可显着减少所需的臭氧剂量，减少的污泥量是传统臭氧处理的一半（30–150 mgO ₃ gSS ^{– 1}）对废水水质没有负面影响。