Development of Low-Cost Growing Media for Spirulina using Alternative Carbon Sources

Spirulina, a blue-green microalgae is grown commercially throughout the world due to the high protein content and non-toxic features of the algal biomass. The Zarrouk’s medium which contains Na2CO3 and NaHCO3 as the carbon sources is known to be the standard medium for Spirulina cultivation. Higher purchasing cost of the carbon sources is recognised to be a limiting factor for large-scale cultivation. Low-cost alternative sources of carbon which can replace Na2CO3 and NaHCO3 in the Zarrouk’s medium has a great economic impact on the commercial production. This study aimed at assessing the growth of Spirulina in different alternative sources of carbon under different concentrations. Table sugar, cassava flour, sweet potato flour and taro flour were used as alternative sources. The Zarrouk’s medium was substituted with different levels (25%, 50%, 75% and 100%) of the solutions prepared with the alternative carbon sources. The algae were cultured at room temperature for 16 days under illumination of 4,000 Lux. The growth was assessed as optical density (OD) using a spectrophotometer at 560 nm and then converted to dry weight (g L-1).According to the results, 100% carbon in the Zarrouk’s medium could be replaced by taro flour and 50% carbon could be replaced by cassava flour. A significantly higher dry weight (1.033 g L-1) was recorded from taro flour at 100% replacement level at the end of 16-day incubation. Therefore NaHCO3 and Na2CO3 in the Zarrouk’s medium could completely be replaced by taro flour solution which substantially reduces the cost of production as well. Cassava flour solution could also be used as an effective replacement while mixing with Zarrouk’s medium into the ratio 1:1. Table sugar and sweet potato flour are found to be poor sources of carbon to replace the NaHCO3 and Na2CO3 in the Zarrouk’s medium. The results could be further confirmed by assessing the growth of Spirulina under different supplementary levels of taro and cassava flour.Keywords: carbon sources, growing media, low-cost, Spirulina, Zarrouk’s mediu

Classification of Finger Joint Timber Based on Strength Index

At present, off-cut wood pieces are dumped by sawmills as they are considered to be wastes in the wood industry. Inadequate length of sawn timber material is also reported to be a limiting factor for fully utilization of timbers. Finger joint, a method which connects two small pieces of timber together is identified as a sound technique to minimize the wastage. As there is no classification system applicable for finger joint timber in Sri Lanka, the present study focused on developing a classification system for selected 32 timber species based on their strength properties. The relationship between the strength properties and density of selected timber species was also investigated. Strength properties of finger jointed timber species were evaluated by three-point bending and compression tests according to BS 373:1957 using Universal Testing Machine (UTM-100).Factors were identified through an analysis to determine the strength index for the selected samples. The strength index values were grouped into five strength classes as very low, low, medium, high and very high. Cluster analysis was used in grouping the species with similar strength properties. Regression analysis was performed to identify the strength index of compression parallel to grain, compression perpendicular to grain, modulus of elasticity and modulus of rupture varies on density. A significant correlation (p=0.05) between the strength index and timber density was observed.Keywords: Finger joint, timber classification, universal testing machine, strengthinde

Analysis of Customer Satisfaction and Prices of Finger Jointed Wood Products

Wood is the most valuable and versatile natural raw material which use to fulfill timber requirements of people. State Timber Corporation is the prioritise leader which introduced various innovative concepts and products to public on utilisation timber in sustainable manner. Finger joint (FJ) technique is one of the most sustainable, eco-friendly and economically valuable innovative concepts for Sri Lankan furniture industry. In this technology small timber pieces which removed as waste are jointed together using glued finger joint cut and make new products. By evaluating the risk and benefits of FJ technology it will be essential to do a survey on economic values in FJ furniture. The main objective of the study is to analyse the cost and price difference of the product and consumer preference between FJ furniture and normal furniture. The two furniture items were selected which were made from finger jointed wood (STC B-FJ 0019) and normal wood (STC B-132). Both items have same design, same measurements, same material used and but different type (finger joint and Normal. A predefined questionnaire was distributed among randomly selected 50 customers who visited State Timber Corporation showrooms to measure the awareness and satisfaction on FJ furniture. People have low awareness but high satisfaction about FJ products. Customers were satisfied with price and attractiveness of FJ products and were not satisfied with strength, trust, durability and availability. FJ products were cost effective and benefited for the waste reduction in factories. Due to the finishing labour cost, unit production cost of FJ of (Rs.171.91 ft2) was higher than normal (Rs.147.88 ft2). Although it shows high cost for customers the uniqueness, attractiveness and high demand of FJ products benefited on customers and increase economical background of producers too. FJ technology is good profitable business in furniture production sector of timber industry.Keywords: Finger joint cost, Risks, Benefits, State Timber Corporatio

A Study on the Compression Strength Performance of Finger Joints in Commonly Used Timber Species in Sri Lanka

Finger joint technique is used to eliminate wood defects which weaken the strength of sawn wood plank. The variation of compression strength of seven wood species commonly used for manufacturing furniture in Sri Lanka was investigated to assess finger joint efficiencies of wood species. Stratified random sampling was applied to measure compression tests in un-jointed andfinger-jointed samples. BS 373:1957 was used as the standard for test conducted with one Softwood species Pine (Pinus caribaea) and Hardwood species; Grandis (Eucalyptus grandis), Jack (Aartocarpus heterphyllus), Kumbuk (Terminelia arjuna), Big leaf Mahogany (Swietenia macrophylla), Satin (Chloroxylon swietenia) and Teak (Tectona grandis). Two finger lengths (13 mm and 19 mm) were used and tested by Universal Testing Machine, using polyvinyl acetate adhesive. Data were analysed by using ANOVA and Duncan's Multiple Range Test at 0.05 significant level. It was observed that the highest joint efficiency was recorded in 19 mm fingerjointed specimen of Grandis followed by 13 mm finger jointed Pine specimen for compression parallel to grain. The least joint efficiency was recorded in 13 mm finger jointed specimen of Kumbuk. Strength of compression perpendicular to grain of 19 mm finger-jointed specimens showed better performance than clear specimens, except Jack and Teak. Limited availability of historical data was a constraint during the study and Sri Lankan context, little effort has so far made on finger jointed manufacturing. The results will be utilised in the commercial application of finger joint manufacturing industry and useful to the traders and planners of the timber industry.Keywords: Compression strength, Finger joint, Efficiencies, Timbe

Identifying the Strength Grade for Finger Jointed Timber Species According to BS 5268-2:2002

Off-cut wood is currently considered as waste thus is dumped by saw mills as they find no means of utilising them. Sawn timber material of furniture factories and short length of sawn timbers are also considered to be wastes in the timber industry. Finger jointing technique which interlock the end joints formed by machining a number of similar tapered symmetrical fingers are recognised in this regards as effective and sustainable means of utilisation of timber wastes. The present study was undertaken to assess the strength grade of finger jointed timber based on BS 5268-2:2002. Seven timber species which are commonly used in Sri Lanka were employed for the assessment with and without finger joints. Values of Modulus of Rupture (MOR), Modulus of Elasticity (MOE), Compression parallel to grain and Compression perpendicular to grain strength of the specimens were measured. Finger jointing was performed with constant geometry (finger length 19 mm, tip width 1 mm and finger pitch 4 mm) using polyvinyl acetate (PVA, P-SWR) adhesive at normal exposure conditions. The strength properties were evaluated by Universal Testing Machine (UTM) according to BS 373:1957. Strength classes relevant to the grade stresses were not significant for finger jointed and clear specimens of Satin, Mahogany, Jack and Grandis. Both clear and finger jointed timber specimens obtained D40 for Satin and Teak, D30 for Jack, Mahogany and Grandis. Teak shows properties similar to both D35 and D40 when used as finger jointed timber. Kumbuk was shown to change from D40 to D30 while using as finger jointed timber. Finger jointed Pine showed stress grade of C22, C24 and C27

Identifying the Strength Grade for Finger Jointed Timber Species According to BS 5268-2:2002

Finger joint technique is used in eliminating wood defects which weaken the strength of sawn wood plank. However, issues related with the strength of the joints, are still not fully investigated under Sri Lankan condition. Finger joint is performed with constant geometry (19 mm Finger Length, 1 mm Tip width and 5 mm finger pitch) using Polyvinyl acetate (PVA, P-SWR) adhesive at normal exposure conditions. The strength properties of clear and finger jointed timber are evaluated by according to BS 373:1957 by Universal Testing Machine (UTM 100 PC). The present study was undertaken to assess the strength grade for finger jointed timber with BS 5268-2:2002 according to the grade stresses at allowable limit gives comparison study of finger jointed and un-jointed seven wood species. Seven commonly used timber species in Sri Lanka were studied. Modulus of Rupture (MOR), Modulus of Elasticity (MOE), Compression Parallel to Grain and Compression Perpendicular to Grain strength values were measured without finger joint (clear) and with finger joint specimens. Strength classes relevant to the grade stresses were not changed for finger jointed and clear specimens for Satin, Mahogany, Jack and Grandis. Both clear and finger jointed timber specimens obtained D40 for Satin and Teak, D30 for Jack, Mahogany and Grandis. While they were used as finger jointed timber, Teak shows properties similar to both D35 and D40. Kumbuk has been changed from D40 to D30 while use as finger jointed timber. Finger jointed Pine shows properties of C22, C24 and C27.Keywords: Finger joint; Grade stress, Universal testing machin