Wenbo, Liu (2011)

Theme

The influence of reducing acid capacity on hydrolysis of activated sludge components

Subject

There is a multitude of biochemical and chemical reactions that are of great importance for wastewater treatment. One of the most important processes is the complex of nitrification/ denitrification in connection with the balance of calcium carbonate/carbonic acid. In this regard, nitrification reduces acid capacity, denitrification produces acid capacity. Therefore, the pH-value of the system is influenced.

This master thesis entails the operation of 2 reactors on the laboratory scale to research the influence of acid capacity and ph-value on the organic and mineral sludge components. For this reason nitrification is systematical increased whereas denitrification is restrained by intensified aeration. The connection between hydrolysis, cleaning capacity and sludge characteristics influenced by acid capacity has to be analyzed.

A detailed literature overview about the knowledge of hydrolysis influenced by reduction of pH-value has to be given as well as brought into connection with the results of the laboratory experiments.

Abstract

The effect of pH on the hydrolysis and sludge reducing of waste activated sludge (WAS) was investigated. It was observed that pH was reduced by nitrification process under the continuous aerobic supply in two barrel reactors (BR). Experimental results showed that at room temperature the sludge hydrolysis was in the following order: acidic > blank test > neutral. Between pH 5.0 and 6.5, the sludge hydrolysis decreased with the increasing pH. Calcium as a tracer of mineral component of sludge was studied. The result showed that 20 mg/l of calcium can be dissolved from the influent of raw WAS. However, the result of oxygen uptake rate (OUR) indicated that the activity of sludge decreased due to the nitrification process under the aerobic condition. Additionally, positive correlation between pH and nitrification within pH value of seven was observed.

Supervisors