SIMULATION OF BIO-GEOCHEMICAL PROCESSES IN A COASTAL AQUIFER

Numerical models which discuss about the bio-geochemical processes which take place in coastal aquifers are still limited. Bacteria mediated reduction is one of the main causes which directly contributes to the groundwater quality of coastal aquifers. In this study a two-dimensional numerical model was developed to simulate the bacteria mediated reduction processes which are occurring in the coastal aquifers. The model was applied to a cross section of Kujyukurihama coast in Chiba prefecture, Japan, where a reduced environment has been formed. The objective of this paper is not to provide an orthodox numerical simulation practice, but to convince the numerical modellers; the possibility of the simulation of bacterial reduction processes in coastal subsurface environments. This paper provides a preliminary numerical study of the reduction of MnO 2 and Fe(OH) 3 under anaerobic bacteria mediation. Further researches are needed to improve the numerical simulations on the reduction environments in coastal aquifers

Denitrification of Secondary Wastewater Using Sawdust

This contribution is devoted to the use of sawdust as materials to improve the efficiency of removing nitrate from the secondary wastewater. Sawdust, a relatively abundant and inexpensive material is being investigated as a porous treatment media to enhance removal of contaminants from wastewater. Successful nitrate removal from secondary wastewater has been demonstrated in a laboratory experiment using columns filled with porous soil material and sawdust and/or bamboo chip served as an organic carbon source. While the availability of organic carbon is one of the most important factors that affects denitrifying activity in soil. A mathematical solute transport model was developed to predict the nitrate degradation processes through a natural filter. The model computes changes in concentration over time caused by the processes of advection, dispersion and biological reactions. Results from a laboratory soil-sawdust and soil-bamboo chip columns experiments were used to verify the simulation results of the model. This study demonstrated that denitrification using sawdust as a carbon source can effectively remove nitrate from secondary wastewater when the carbon source is limiting in the influent secondary wastewater or groundwater

Denitrification of Secondary Wastewater Using Sawdust

This contribution is devoted to the use of sawdust as materials to improve the efficiency of removing nitrate from the secondary wastewater. Sawdust, a relatively abundant and inexpensive material is being investigated as a porous treatment media to enhance removal of contaminants from wastewater. Successful nitrate removal from secondary wastewater has been demonstrated in a laboratory experiment using columns filled with porous soil material and sawdust and/or bamboo chip served as an organic carbon source. While the availability of organic carbon is one of the most important factors that affects denitrifying activity in soil. A mathematical solute transport model was developed to predict the nitrate degradation processes through a natural filter. The model computes changes in concentration over time caused by the processes of advection, dispersion and biological reactions. Results from a laboratory soil-sawdust and soil-bamboo chip columns experiments were used to verify the simulation results of the model. This study demonstrated that denitrification using sawdust as a carbon source can effectively remove nitrate from secondary wastewater when the carbon source is limiting in the influent secondary wastewater or groundwater

Numerical Study on Saltwater Instrusion in a Heterogeneous Stratified Aquifer

In a costal aquifer, saltwater intrusion is frequently observed due to an excess exploitation. There are many researches focused on the saltwater intrusion. However, there are few researches, which take into consideration the mixing processes in a stratified heterogeneous aquifer. In the present study, a laboratory experiment and numerical simulation are made in order to understand the phenomena in a stratified heterogeneous aquifer. The result of the numerical analysis agrees well with the measurement and indicates that the saltwater intrusion with the mixing process is dominated by the convection in the high permeable layer and the molecular diffusion in the low permeable layer