Combined Treatment Of An Organic Chemical Water
By Activated Sludge Followed by Activated Carbon
EDWARD S.K. CHIAN, Associate Professor
YUEH CHANG, Graduate Student
FOPPE B. DE WALLE, Research Assistant Professor
Department of Civil Engineering
University of Illinois
Urbana, Illinois 61801
W.B. ROSE, Engineer
Daily Associates Engineers, Inc.
Champaign, Illinois 61820
INTRODUCTION
Pretreated lagoon effluent of an organic chemical industry manufacturing household
aerosol products was added to an activated sludge unit receiving municipal sewage to
evaluate the effect of the combined municipal and industrial waste on the performance of
the unit. The effluent of the activated sludge unit was further treated by activated carbon in
the presence of biological growth.
The organic chemical industry manufacturing 150 x IO6 units per year of aerosols,
liquid packaging of household products, chemical specialities, cosmetics, pharmaceuticals
and foods, produces a 50 percent probability waste stream of approximately 60,000 gpd (1).
Eleven analyses of 24-hour composite samples of the waste stream showed an average BOD
of 3,400 mg/1, a COD of 6,000 and a BOD/ COD ratio of 0.57 indicating that the majority of
the organics is biodegradable (1).
The waste consists for a large part of petroleum distillates (kerosenes), alcohols (is-
opropyl and ethyl alcohol), chlorinated solvents (methylene chloride and chlorothene),
aromatic compounds (benzene, toluene and xylene), and glycols, all subject to a variable
degree of biological decomposition (2). Ground water polluted by slags and residues from a
zinc extraction and processing industry, previously located at the same site, infiltrated to
some extent into the industrial sewers and added several heavy metals such as zinc and iron
to the waste stream (1).
LAGOON TREATMENT OF THE INDUSTRIAL WASTE
The industrial waste stream is passed through an aerated lagoon having a 5-day
detention time. As the BOD:N:P weight ratio of the raw waste was 566:4:1, N and P were
added to the aerated lagoon to improve the nutrient balance. After the aerated lagoon, the
waste enters an anaerobic lagoon in which a slow biological degradation occurs. After a
nine-month holding period, for example, the BOD decreased from approximately 3,000 to
966