Abstract

This research provides an approach for designing a constructed wetland system for treatment of tin contaminated wastewater from mining catchment. Initially, physico-chemical characteristics and concentration of heavy metals in the soil and ponds were evaluated. It was found that the soil and water quality of the area is highly degraded. This study will help for the design of the wetland for wastewater treatment. Design of wetland was mostly based on the review of scientific literature, theoretical modelling and verification of performance via a pilot system. The wetland system comprises of three compartments in series: an ‘inflow’ pond receiving untreated tailings water overflowing into a wetland compartment which in turn overflows into an ‘outflow’ pond receiving the now treated water. Waterproofbaffles in each wetland compartment serve to increase the flow path of the water, thereby increasing the potential for sulphate retention. On site a computer connected to the pumps regulates the flow of tailings water through the systems. The wetland compartment of each system is filled with approximately 50 cm depth of a mixture of the cattle manure as (25%) and municipal waste compost (75%) as substrate. This mixture has good permeability with optimal growth of plants.Additionally 30 tonnes of limestone will be deposited at the far end of the wetland to facilitate final pH adjustment if it should be required. At the bottom of the inflow and outflow ponds in each system, a layer of about 25 cm of a 1:6 mixture of cattle manure and municipal compost is deposited to provide a substrate for the invertebrate species that spontaneously inhabit the systems. The planting density chosen is based on similar research on constructed wetlands. Proposed anaerobic wetland is first of its kind introduced for mining waste water treatment in Malaysia.

Key words: Water quality, heavy metals, soil, water, constructed wetland, wastewater treatment, anaerobic system.