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Research background. Lovastatin is a well-known drug used to reduce hypercholesterolaemia. However, the cost of lovastatin production is still high. Therefore, alternative low-cost carbon sources for the production of lovastatin are desirable.Experimental approach. Four different agricultural wastes, namely corn trunks, rice husks, wild sugarcane, and soya bean sludge, were tested separately as substrates to produce lovastatin using a new fungal strain, Aspergillus sclerotiorum PSU-RSPG 178, under both submerged and solid-state fermentation (SSF).Results and conclusions. Of these substrates and cultivation systems, soya bean sludge gave the highest lovastatin yield on dry mass basis of 0.04 mg/g after 14 days of SSF at 25 °C. Therefore, the soya bean sludge was separately supplemented with glucose, wheat flour, trace elements, palm oil, urea and molasses. The addition of the palm oil enhanced the lovastatin yield to 0.99 mg/g. In addition, the optimum conditions, which gave a lovastatin yield of (20±2) mg/g after 18 days of SSF, were soya bean sludge containing 80 % moisture (dry basis) at a ratio of soya bean sludge (g) to mycelial agar plugs of 1:4, and a ratio of soya bean sludge (g) to palm oil (mL) of 1:2. Besides, the lovastatin yields obtained from SSF using fresh or dry soya bean sludge were not significantly different.Novelty and scientific contribution. We conclude that A. sclerotiorum PSU-RSPG 178 has a good potential as an alternative strain for producing lovastatin using soya bean sludge supplemented with palm oil as a carbon source.

A crucial property of fibrous packaging paper for food is water resistance, while strength properties are also important. To improve these properties, several bio-coating solutions were applied as coatings on paper made of pineapple leaf pulp. The effects of beeswax, chitosan, shellac, alginate/gellan gum and beeswax–chitosan (1% chitosan+4%glycerol+30%beeswax) solutions on pineapple leaf pulp paper were assessed in relation to making biodegradable paper plates. The cooking time (120–180 min) of chemical pulping and the dose of pulp by moist weight (200, 250, and 300 g) to a paper frame (40 × 40 cm2) were also studied on making the paper samples. The papers were tested for their physical and mechanical properties. The optimal cooking time and dose of pulp by moist weight found were 180 min and 300 g of pulp per frame, respectively. The bio-coatings increased average grammage and thickness of paper, but gave density reduction from that of uncoated paper. Coating paper with beeswax–chitosan solution gave the longest absorbency time, followed in rank order by alginate/gellan gum, chitosan, beeswax and shellac. The maximum 5.9 kN/m2 tensile strength was found for paper coated with beeswax–chitosan solution before hot pressing. On comparing papers bio-coated before or after hot pressing, no difference was found in the degradable time with NaAlg/gellan coating, while such difference was observed with beeswax-chitosan coating. The results suggest beeswax–chitosan solution as the best among the alternatives tested, for coating paper to make biodegradable plates.

The potential of waste coffee grounds (WCG) as a non-edible feedstock for biodiesel production was evaluated in term of extraction and esterification of waste coffee grounds oil (WCGO). The effect of liquid-solid extraction parameters such as the type and volume of solvent, the extraction time and temperature, and mixing speed were thoroughly investigated. The highest yield of oil extracted from WCGO was 15.47 wt% obtained at a hexane to WCG ratio of 9:1 (v/w) with a mixing speed of 200 rpm and an extraction duration of 5 min at room temperature. An esterification reaction was conducted as a pre-treatment step to reduce the concentration of free fatty acid (FFA), optimized by response surface methodology (RSM) combined with a central composite design (CCD). The results indicated that all the parameters including the methanol (MeOH) to FFA molar ratio, quantity of catalyst, reaction time and temperature were significant for %FFA removal. In the esterification step, the FFA conversion was 95% at the predicted optimization condition which corresponded to the experimental data. Therefore, the results of this study support the utilization of WCGO as a source of non-edible oil feedstock for biodiesel production.

Ammonium-enriched skim latex serum - used for absorption of contaminating ammonia gas - when composted with other rubber tree wastes, is promising as a good compost. The objective of this research was to utilize ammonium-enriched skim latex serum (S) as a raw composting ingredient after being combined with para sawdust (W1) and para rubber leaves (W2). Several ratios of S, W1 and W2 were experimented in a 15L composting vessel to determine the most effective compost. The best ratio was found to be 3:1:3 by weight at 12-day retention. The modified 30 L composting reactor employed with the derived optimum mixing conditions yielded N, P and K of 2.40, 1.51 and 14.84 %w/w. The growth of Brassica alboglabra after application of this compost combined with a chemical fertilizer generated the highest fresh weight (4.48 g/plant). Thus, compost from these wastes could be used as a fertilizer and logically should contribute to cost saving of waste disposal.

The aim of this study was to investigate the effect of microwave pretreatment on the properties of particleboard made from para rubber wood sawdust with the addition of polyhydroxyalkanoates (PHAs). Para wood sawdust was pretreated with microwaves at different wattages (400, 600 and 800 W) and pretreatment times (5, 10 and 15 min) before being mixed with 10 wt. % of pure PHAs and 10 wt. % freeze-dried cells which contained 46.90% wt. % PHA, in order to make particleboard. The physical and mechanical properties of the particleboard panels obtained were also tested based on the Japanese Industrial Standards A 5098 for particleboard (JIS A5908) including modulus of rupture (MOR), internal bonding (IB), water absorption (WA) and thickness swelling (TS). The results showed that only panel made from 10 wt. % freeze-dried cells and treated with 400 watts for 5 min passed the minimum requirement of IB (1.62 ± 0.06 MPa) and nearly passed that of MOR (7.86 ± 0.67 MPa) but not passed that of WA (40.09 ± 6.53%) and TS (34.69 ± 5.43%). The panels without the addition of PHA cannot test WA and TS values because the panels dispersed immediately when submerged in water. The MOR of panels decreased with increasing wattages and pretreatment time. The wattage and pretreatment time of microwave had little effect on the WA and TS. Based on this study, microwave treatment is an appropriate method for the pretreatment of materials and PHAs can be promoted as potential additives for making particleboard.

Polyhydroxyalkanoates (PHAs) can be used to replace petrochemical plastics in many applications. However, their production has limitation due to production cost. This research was conducted using alternative carbon source from waste to synthesize PHAs by Cupriavidus necator H16. In this study, PHAs were produced from used cooking oil (UCO) and compared with production PHAs from palm oil. Two UCO storage times (4 and 10 weeks) and three UCO concentrations (10, 20 and 30 g/L) were used to determine the most optimum condition for PHA synthesis. The best optimum condition for PHA synthesis was cultivated in the medium containing 30 g/L of UCO at 4 weeks storage. The cell dry weight (CDW) and PHA content were 5.26±0.61 g/L and 27.36±2.04 wt. %, respectively. These results were similar to cell cultivation using 20 g/L palm oil and 1% of fructose (5.93±0.33 g/L of CDW and 26.96±6.14 wt. % of PHA contents). In addition, PHA content from the culture with 10 g/L of UCO stored for 10 weeks was higher than PHA content from the culture with 20 and 30 g/L of UCO. Thus, it can be concluded that UCO could be used in PHA production.

Different concentrations of palm oil and urea were used in a preliminary experiment conducted in a shake-flask to determine the optimum conditions for the biosynthesis of polyhydroxyalkanoates (PHA). The best concentration was found to be 10 g/L palm oil and 0.54 g/L urea which produced the highest concentration of PHA (8.11 g/L). A 13 L bioreactor was employed using a fed-batch fermentation with the derived optimum conditions and yielded a PHA concentration of 97 g/L. The melting temperature and thermal degradation temperature of PHA were determined to be 173 °C and 254 °C, respectively. The PHA was applied as a binder to make particleboard from para-rubber-wood flakes which were pretreated with microwaves and steam before being mixed with PHA, and control panels were also manufactured from un-pretreated flakes and without the addition of PHA. The mechanical and physical properties of the panels were determined including the modulus of rupture (MOR), internal bond strength (IB), water absorption, and thickness swelling according to the Japanese Industrial Standard for particleboard (JIS A 5908, 2003). The result showed that none of the panels produced met all the minimum requirements for Type 8 Particleboard of Japanese Industrial Standard JIS A 5908. The MOR of the control panel passed the JIS A 5908 standard for MOR (> 8.00 MPa) but did not meet the IB requirement (>0.15 MPa). The addition of PHA as a binder in proportions of 15, 20 and 30 wt% in the control panel enhanced the IB to 0.18, 0.19. 0.22 MPa, respectively. However none of the other parameters of these boards met the relevant JIS A 5908 standard. The pretreatment process was also unable to enhance the properties of the particleboard but that using PHA as a binder instead of urea formaldehyde was able to meet the relevant internal bonding standard for particleboard manufactured from para-rubber-wood flakes which are a waste product in the furniture industry.