Nitrification and Denitrification Activity in the Facultative Pretreatment Pond of a Sea-based Solid Waste Disposal Site

Abstract

At a sea-based solid waste disposal site where intermittent landfi ll is employed to control the concentration of nitrogenous and organic pollutants, nitrifi cation and denitrifi cation activity in the sediment and water of a facultative pretreatment pond were investigated in order to estimate the contribution of these two processes to maintaining the water quality of the pond. Empirically determined activities were evaluated by comparing them with apparent values estimated from the annual change in the concentration of nitrogenous compounds. Nitrifi cation activity in both sediment and water samples was often found to be higher than denitrifi cation activity. The contribution of nitrifi cation activity in water to that in the pond as a whole was estimated to be higher than that in sediment, while the opposite was the case with denitrifi cation activity.

Phosphate Deficiency and Its Effect on Nitrification in the Pond of a Sea-Based Solid Waste Disposal Site

“…Until 1999, a tendency was observed that concentration of T-N was clearly related to BOD and DO, which corresponded to the reclamation of the pond with garbage and sludge 1) . Since 2001, however, when all the wastes disposed of in the pond were restricted to incinerated ash, which is supposed to be less pollutant than raw garbage and sludge, T-N concentration began to show only slight seasonal shifts in summer independent of reclamation ( Fig.…”

“…1b). The base layer and the 1st layer reclamation, processes to dispose wastes in the pond, are conducted intermittently because the anaerobic conditions caused by the heavy load of pollutants in the pond water affect the biological process undesirably 1) . At the beginning in 2006, the surface areas of pretreatment pond, aerated lagoon, and control reservoir were approximately 78,800, 38,700, and 1,080 m 2 , respectively, and the corresponding volumes were approximately 630,000, 330,000, and 4,300 m 3 .…”

“…In the case of the SWDS studied, the HRT of the pond water is more than one year and dissolved oxygen (DO) is relatively high 1) while suspended solids (SS) in the pond water is as low as several g m -3 , which may be insufficient as the base for retaining nitrifying bacteria. Furukawa et al 21) , who introduced immobilized activated sludge acclimated to seawater for retaining dense nitrifying bacteria to treat ammonium in the pond water from the same SWDS as featured in the present study, found IC limitation of nitrification.…”

“…Nitrifying bacteria are susceptible to low temperature 2) . Periodical decrease in summer and increase in winter observed in total nitrogen (T-N) in the pond water indicates suppression of nitrifying activity under low temperature 1) . We have elucidated that the nitrifying activity can be maintained at low temperature when phosphate is added prior to sand and granular activated carbon (GAC) filtration in a potable water treatment plant, where phosphate is eliminated through a coagulation-sedimentation process 19) .…”

“…In the pond water of the sea-based SWDS, we have been studying; nitrifying activity is thought to be low as indicated by the relatively high concentration of nitrogen compounds, of which more than 70 % exists as ammonium nitrogen 1) . Elimination of inhibiting factors for nitrification or amendment of the cultivating condition is needed to enhance nitrogen treatment through complete nitrification.…”