Algal primary production in a dredged sludge disposal site

Abstract

Abstract In this report, the CODMn amount produced in the stabilization pond of a dredged sludge disposal site was estimated and discussed. In the AGP (Algal Growth Potential) test of the effluent from the stabilization pond, Skeletonema costatum and Chlorella sp. grew to the cell density of 350,000 (cells)mL−1 (p‐CODMn. 2.1 mgL−1) and 240,000 (cells)mL−1 (p‐CODMn, 10.0 mgL−1), respectively. It was found also these values were increased by addition of the solution of materials from benthal mud and treated wastewater from Site 1 (aerated lagoon). The calculated amount of CODMn produced in the stabilization pond was highest in spring, ranging from 6.8 to 172.7 ton(month)−1. Most of the CODMn amount produced was precipitated, degraded and taken up by Zooplankton in the stabilization pond, and 0.9 to 5.6 ton(month)−1 as p‐CODMn and 4.0 to 6.2 ton(month)−1 as sol. CODMn were discharged. The amount of sol. COD discharged was almost constant throughout the year, which indicated that the CODMn amount lost from th...