Spent bleaching earth as soil conditioner or spent bleaching earth recovery for a total environmental solution to the palm oil refinery

Bleaching earth is used in the bleaching process of physical refining of palm oil to remove colour, phospholipids, residue gums, oxidized products and any trace metals from the oil. These coloured pigments are trapped and absorbed in the bleaching earth, thus transforming the originally whitish earth to dark grey and is, from then, named spent bleaching earth (SBE). SBE is considered as an industrial by-product as there is hardly any practical application for it. Large quantity of SBE is commonly disposed off in landfills, which poses potential hazards to the environment. New economical ways in utilizing it is sought to eliminate the problem arises from its disposal.This paper presents a study on the possibility of developing a soil conditioner using enhanced SBE (ESBE) as the base material. The study indicated that certain attributes in the ESBE could be of advantages for it to provide a remedy for soil improvement. Analyses conducted to investigate the chemical, physical and biological properties of the ESBE were water holding capacity, cation exchange capacity, nutrient and elemental content, oil content, fattyacid compositions, pH, particle size, surface area and beneficial microorganism (microbial activity). It was discovered that the ESBE contains some important essential nutrients like nitrogen, phosphorus, potassium, calcium, magnesium, manganese, zinc, iron, boron and copper which promote plant growth. The presence of about 18-20% residue oil is believed to exhibit good water holding capacity and slow release (if water once it is mixed with soil. TheESBE is able to hold 20 ml of water per 100 g of dried sample while the soil mixed with SBE can hold 50 ml of water. The small scale field evaluation & efficacy testing on plant growth was conducted on red lady finger (Abelmoschus esculentus) using the ESBE as soil amendment. Two types ofsoil with three planting pots each were set up using a mixture of the ESBE and soil over the control (soil without the ESBE). Several analyses were performed to determine the plant growth (growth rate and yield data) by determining the variousparameters affecting the overall increased (composite) standing biomass such as plant height, number of leaves,fresh weight, dry weight and shoot-root ratio. The results which was subjected to statistical analysis using t-Test showed that the use of ESBE in the plant trial was significant (P value lower than 0.05) in terms of its shoot growth.