The influence of the dosing quantity of activated carbon on the
COD removal efficiency in wastewater was determined at a fixed
adsorption time of 20min by adding different amounts of activated
carbon into 100 ml coking wastewater at 25 ◦C It can be seen in Fig. 2 that as the dosing quantity of activated carbon
increased, the removal efficiency of activated carbon for COD
in coking wastewater increased gradually. When the dosing quantity
of activated carbon was 9 g/100 ml, however, the COD removal
efficiency reached amaximum. Past this point, increasing amounts
of activated carbon in the system no longer caused any apparent
change. These results can be explained that with the increase of
the amount of activated carbon as well as of the provided adsorption
surface area in the wastewater, the content of chemicals in the
wastewater reduced. When the chemicals in the wastewater were
below a certain concentration, continuing to increase the amount
of activated carbon no longer exerted an influence on the removal
of chemicals in the wastewater. In addition, when the wastewater
was adsorbed at this dosing quantity of activated carbon, the COD
values of the wastewater reached 130.2mgL−1. The optimal dosing
quantity of activated carbon was therefore determined to be
9 g/100 ml coking wastewater.