The greenhouse represents our first experience with indoor treatment systems. It is, therefore, designed for flexible operation making use of interchangeable parts. The aquatic plants and soil mixtures chosen for the greenhouse as a final purifying stage will be determined based on the “coarse to fine principle”.

Aquatic plants are typically adapted to smaller concentrations (fine) of nutrients than are wetland plants, and therefore come at the end of the treatment process. Upland plants typically have higher nutrient requirements (coarse). This follows the natural model of water moving from land to marsh to open water. Treatment in the constructed ecosystem follows the same model.

Tropical vegetation will be used within the modular planter boxes because of its potential adaptation to low nutrient environments.

The “soil filter media” within the boxes will permit the evaluation of different solid waste materials as water cleaning mediums. We will continue to study the effectiveness of crushed brick for cleaning water. Crushed brick is a solid waste by-product of an extensive local industry, and its use as a wastewater management material provides an opportunity for recycling of this resource.

Experiments to be conducted with different materials in the six chambers of the greenhouse planter boxes will provide an important, albeit limited, comparison of materials.