This research was conducted to formulate plant growing medium from activated sludge of a coal-fired power plant wastewater treatment system. Experimental procedure was divided to 3 steps; 1) the physical properties development, 2) chemical development and 3) planting test.
Initiated with the physical properties, 4 local materials as rice husk, sawdust, bagasse and coconut fiber were selected to reform sludge properties. Mixed the mentioned materials with sludge as various ratio. Depending on water absorption and bulk density, it was indicated the rice husk and sawdust were mostly appropriated to adjust sludge properties. Additionally, ratio of sludge (SL): sawdust (SD): rice husk (RH) was analyzed also found the ratio of SL:SD:RH equaled 5:1:1 was practically suited for physical properties due to the water absorption and bulk density values which equaled 43.2±0.01% and 0.353±0.07 g/cm3 respectively.
Subsequently, the improvement of chemical properties of growing medium was proceeded, 2 easily methods as mixing and mung bean composting with sludge were compared. Results were represented that, sludge composted with mung bean had highly values of Available-N as NH4+-N. On the contrary, the properties of growing medium improved by both methods, it was not detected NO3_N but similarly found the Available-P and organic matter. However, the Available-K level detected from sludge composted by mung bean was more than sludge admixed dominantly.
For plant testing experiment, the result was revealed the plant could alive in growing medium well indicated from the quantity of leaf and stalk height of bird chili and tomato planted in growing medium were higher than planted in loamy soil significantly (P<0.05).
Eventually, it was summarized SL:SD:RH equaled 5:1:1 composted sludge with mung bean might be more appropriated to use as growing medium.