Combination of Activated Carbon with Biological Wastewater Treatment at Full-Scale - Activated Carbon for Water and Wastewater Treatment - page 130

When the petrochemical wastewaters emerge mainly from the production of a
single compound such as vinyl chloride monomer, high concentrations of that
chemical are often observed in the wastewater. Vinyl chloride-containing waste-
water from a South African petrochemical company was successfully treated in a
PACT unit. High-quality wastewater was produced for reuse in production [2].
Pilot tests with a two-stage PACT system showed that the TOC of the wastewater
went down from 910 to 160mg L 1 in the first stage and further to 60mg L 1 in
the second stage. The aim was to decrease TOC below 5mg L 1 in order to comply
with reuse standards. For this purpose, a full-scale PACT system was constructed
along with UV oxidation as a post-treatment step. Although the standards for
reuse could not be achieved, the full-scale PACT system performed better than the
pilot-scale system and decreased effluent TOC to less than 20mg L 1 .
In the industrial park Renda in TaSheh Taiwan, a single-stage PACT system was
combined with WAR to treat chemical and petrochemical wastewaters. The aim
was to meet effluent standards of COD ( 80mg L 1 ) (Figure 5.2). The wastewater

had a BOD 5 /COD ratio less than 0.1, indicating very low biodegradability. In the
treatment system, the aeration tank and clarifiers were designed to handle high
levels of mixed liquor suspended solids (MLSS). The MLSS concentration in the
PACT sludge was about 22 000mg L 1 . The MLSS was made up of approximately
15% biomass, 55% carbon, and 30% ash. It was ensured that sufficient carbon was
maintained in the system to meet the stringent effluent COD and color limits.
Effluent COD values could be decreased to below 90mg L 1 while negligibly small
BOD 5 values (1-3mg L 1 ) were recorded [3].
Recycling of wastewater was investigated at a coal gasification facility in South
Africa [12]. Wastewaters at the facility stem from various oily and organic wastes
that are generated in coal gasification. For the additional removal of organic
matter, nitrification of nearly 500mg L 1 ammonia, and adsorption of recalcitrant
compounds, an activated sludge system with PAC addition was introduced

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Figure 5.2 Full-scale PACT at Renda Industrial Park (RIP) in TaSheh,
Taiwan [3]. (permission received)