Abstract

Muhammad Aqeel Ashraf¹*, Mohd. Jamil Maah¹ and Ismail Yusoff²

This research provided an approach for designing a constructed wetland system for treatment of tin-contaminated wastewater from mining catchment – a system that is known to provide a more economical treatment than the conventional system. Initially, physic-chemical characteristics and concentration of heavy metals in the soil and ponds were evaluated. It was found that the soil and water quality of 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 consisted of five mined out ponds in the catchment, each pond arranged in series with a 48-hr hydraulic retention time. . The 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. Waterproof baffles in each wetland compartment serve to increase the flow path of the water, thereby increasing the potential for sulphate retention. On site a computer (ACS Pentium PC) connected to the pumps regulates the flow of tailings water through the systems. The wetland compartment of each system is filled with approximately 50cm depth of a mixture of the cattle manure as (25%) and municipal waste compost (75%) as substrate. This mixture was chosen because literature shows that it combined 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 25cm 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 introduce for mining waste water treatment in Malaysia.

Water quality; heavy metals; soil; water; constructed wetland; wastewater treatment; anaerobic system

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