BIO-SURF NITRIFICATION OF
CONCENTRATED AMMONIA-BRINE WASTE
FROM AN IODINE MANUFACTURING PLANT
Charles C.-S. Chou, Manager
New Products Development
Autotrol Corporation
MUwaukee, Wisconsin 53209
T. Daicho, Process Engineer
Nippon Autotrol Kabushiki Kaisha
Tokyo, Japan
INTRODUCTION
Nippon Chemicals Company is a major producer of halogens and halogenated organics
in Japan. Its iodine plant, located in Chiba Prefecture, 100 kilometers east of Tokyo,
obtains the halogen from an iodide-rich brine. Various agricultural, medicinal and industrial
chemicals are synthesized from iodine, bromine and natural gas. The brine contains approximately 100 mg/1 sodium iodide. A blowing-out process is employed for the recovery
of iodine in which iodide is oxidized by gaseous chlorine and stripped out of the brine
liquor. Iodine is subsequently purified and crystallized as starting material for many downstream uses.
In the past, the waste brine was discharged into a river after iodine recovery. This wastewater contains salt as concentrated as sea water and has about 200 mg/1 ammonia nitrogen
[lj. There are a few iodine plants in the same area and all have discharged their wastewater
directly into the nearby river. The river has also been a source of irrigation water. The high
salinity and ammonia content of the river water during rice growing season, when the river
flow rate is low, has had adverse effect on the crop. Therefore, the iodine works had kept
the flow rate of wastewater in accordance with that of the river water, although no legal
restriction on this river was enacted as to the discharge level of ammonia and salt concentration. However, it was difficult to regulate the discharge flow due to the variation of iodine
production. Consequently, a common pipe line was laid to transport the brine waste directly
into an estuary several kilometers away on the seashore of the Pacific Ocean. As a preventive
measure, these iodine plants have worked out a discharge limit with a fishermen's union and
the prefectural government, since active fishing has been conducted at the estuary and near
the seashore. The agreement restricts ammonia nitrogen to less than 1 10 mg/1.
To meet the ammonia discharge level, Nippon Chemicals Company has conducted a
rather extensive feasibility study on several alternative treatment processes. The rotating
biological contactor (RBC), activated sludge process and an ammonia stripping system were
selected for the study. After thorough pilot testing and cost comparison, the company came
to a conclusion that the RBC was the most cost-effective process because of its lowest total
cost, minimal secondary pollution, simple operation and maintenance procedures and ease
of future expansion.
This chapter will discuss the initial pilot study, design rationale and the operating experience of the full-scale RBC treatment.
NITRIFICATION OF CONCENTRATED AMMONIA OR HIGH SALINITY WASTES
In the 1970s attention was extended to high-strength ammonia waste. Lue-Hing and his
colleagues conducted a nitrification study of digester supernatant by a 0.5-m-diameter 4-
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