Oil palm is the one of the most popular oil crop in many regions of the world and it plays an important role as a component of animal feed and as a cooking material in an industrial sector. However, every ton of oil produced generates tons of effluent and this cannot be released to the environment directly as it causes environmental pollution due to its high biological and chemical oxygen demand. Therefore, an experiment was conducted to investigate the potential use of oil palm decanter cake as an ingredient to prepare a low cost ration for 36 cross bred pigs (Land race* Large white) using complete randomized statistical design. Four different ration such as 1:1 poultry offal and decanter cake (T1), 3:1 poultry offal and decanter cake (T2), commercial ration (T3) and mixed feed (poultry offal, decanter cake, rice bran and beer pulp; T4) were fed to pigs during growing stage. Growth performances; daily intake (DI), daily weight gain (DWG) and feed conversion ratio (FCR) were determined during the experiment and carcass quality parameters; carcass depth, carcass length, back fat thickness (BFT) and dressing percentage were measured at the end of the experiment.

Results demonstrated that the daily intake was highest (4.2 ± 0.15 kg/day) in pigs fed with T4 ration compared to the other rations due to nutrient imbalance with deficient residue composition. Although commercial ration shown that lowest intake and FCR (1.99 kg/day and 3.57 ± 0.27) together with highest weight gain (562.5 ± 44 g/day) mainly due to proper nutrient balance. Live weight, carcass weight and carcass depth of the pigs fed with T1, T2, and T3 rations were significantly different (P < 0.05) than T4 which have the lowest value (81 ± 5.17 kg, 62.33 ± 4.64 kg and 33.33 ± 0.67 cm). However, carcass length of the animals was not significantly different (P < 0.05) between fourtreatment because the length mainly depends on genetic factors. Pigs fed with commercial ration shown that highest back fat thickness of 4.47 ± 0.39 cm. Since, there is no significant difference (P < 0.05) of the BFT among the treatments.

The results suggest that, in spite of the DWG and high FCR observed with T1 and T2, the carcass characteristics are not different as compared with pigs fed with commercial ration. Therefore, the results of this study conformed that decanter cake could be used as a substitute in pig rations to reduce the cost and also to utilize by product of oil palm effluent to minimize environmental pollution.

R A U J Marapana and R T Seresinghe
Department of Animal Science, University of Ruhuna, Sri Lanka.

From Proceedings of the International Forestry and Environment Symposium 2006 of the Department of Forestry and Environment Science, University of Sri Jayewardenepura, Nugegoda, Sri Lanka (22-23 December, 2006, Wadduwa, Sri Lanka)

One of the major burning problems in urban areas is the disposal of sewage water, which degrades the environment, and as well as creates health hazards to human beings. One opening to this bottleneck is that this sewage water could be diverted for irrigation purpose especially for afforestation purpose. Sewage water provides nutrients and using it for irrigation has been found to enrich soil, improve uptake of plants and ameliorate degraded soils. It was found that sewage water irrigated tree species recorded maximum height and basal diameter when compared to bore well water irrigation. It showed that it boosted the growth of tree species. Hence the utilization of sewage water as irrigation water for tree crops is the one of best option for increasing biomass and protecting environment deterioration from deforestation of land and water by sewage water.

In this context, a field experiment was conducted at sewage farm and the following tree species viz., Eucalyptus tereticornis, Tectona grandis, Casuarina equisetifolia, Azadirachta indica and Acacia nilotica were planted and irrigated with sewage water at 2 weeks interval. The same 5 species were also planted near the sewage farm and irrigated with bore well water. The growth parameters viz., height and basal diameter were recorded at periodical interval. The results revealed that the height and basal diameter of all the five selected tree species were higher under sewage water irrigation when compared to bore well water irrigation. The results inferred that at 3 MAP, the percent increase in height and basal diameter respectively was 15 % and 18 % for Casuarina equisetifolia, 39 % and 20 % for Tectona grandis, 17 % for Acacia nilotica, 24 % and 20 % for Azadirachta indica, 23 % and 18 % for Eucalyptus tereticornis over bore well water irrigation. At 6 MAP, the percent in height and basal diameter was 7 % each for Casuarina equisetifolia, 13 % and 6 % for Tectona grandis, 13 % and 6% for Acacia nilotica, 15 % and 9 % for Azadirachta indica, 14 % and 12 % for Eucalyptus tereticornis under sewage water irrigation over bore well water irrigation. At 9 MAP, the increase in height and basal diameter was 8 % each for Casuarina equisetifolia, 9 % and 6 % for Tectona grandis, 12 % and 9 % for Acacia nilotica, 10 % and 4 % for Azadirachta indica, 21 % and 11 % for Eucalyptus tereticornis over bore well water irrigation. At 12 MAP, increase in height and basal diameter was 7 % and 4 % for Casuarina equisetifolia, 7 % and 4 % for Tectona grandis, 6 % and 4 % for Acacia nilotica, 47 % and 4 % for Azadirachta indica, 8 % and 7 % for Eucalyptus tereticornis over bore well water irrigation. At 15 MAP under sewage water irrigation, the percent increase was 4% each for Casuarina equisetifolia, 5 % and 3 % for Tectona grandis, 6 % and 5 % for Acacia nilotica, 7 % and 5 % for Azadirachta indica, 10 % and 8 % for Eucalyptus tereticornis over bore well water irrigation.

From the study, it was found that sewage water can be better used for raising tree plantation on relatively unfertile wastelands through afforestation, urban forestry plantation, social forestry plantation to safeguard the planet earth from global warming, severe drought, adverse climatic condition, pollution etc.

M P Divya, K Srinivasan and M G Rao
Forest College and Research Institute, Tamil Nadu Agricultural University, India

From Proceedings of the International Forestry and Environment Symposium 2006 of the Department of Forestry and Environment Science, University of Sri Jayewardenepura, Nugegoda, Sri Lanka (22-23 December, 2006, Wadduwa, Sri Lanka)

The effectiveness of seven locally available natural organic materials as oil spill sorbents was tested. The study specifically focused on determining, the behaviour of loose material on a layer of oil, oil sorption capacity of different types of materials and the viability of using them under actual field conditions. The seven natural organic materials were chosen based on their availability and cost. The amount of oil sorption by each was determined by the gravimetric method and the rate of sorption was determined. A commercially available synthetic oil sorbent, polyurethane, was used as the positive control. Out of the seven natural organic materials tested, human hair was found to be the most effective sorbent. Compared to the positive control, Polyurethane, there was no significant difference with respect to the oil sorption capacity of human hair. Therefore, all the subsequent experiments were carried out using human hair only. As hair has a tendency to sink in sea water after oil sorption, hair was compacted in to pillows to facilitate the recovery after sorption. First, the affect of the pillow thickness on the oil sorption capacity was tested. Oil sorption capacity increased significantly as the thickness of the pillow increased and a thickness of 1cm was found to yield the most efficient sorption. Then sorption capacity of oil by pillows was compared on a sea water oil interphase, only on oil and oil on sand. No significant difference was detected in the oil sorption capacity of hair filled pillows under these three conditions. Finally, a field trial was conducted where pillows were developed up to the size of commercially available synthetic pillows and placed on an artificially created oil spill and tested the oil sorption capacity under actual field conditions. A total of four pillows were used for the field trial and the pillows were removed at different time intervals after placing it on the artificial oil slick. The results of this experiment were not conclusive as amount of oil absorbed by all four pillows did not reach the expected value calculated based on results obtained during laboratory experiments, due to several shortcomings in the experimental design. The results of this study clearly demonstrate that human hair can be used as an effective oil sorption material. As waste human hair is cheap and readily available, it is a much more viable alternative to expensive synthetic organic material available in the market.

L A C S Piyadasa, D K Weerakoon and S W K Kotagama
Department of Zoology, University of Colombo, Sri Lanka

Dumping of sewage sludge in the outer of cities leads to silting of nearby tanks, polluting the lands and also air they burn, which is a burning problem in urban areas. This sewage sludge is rich in nutrients and their use has been found to improve the physical condition of the soil as well as increase productivity of green biomass. As it contains heavy metals it threatens the human life by way of entering into food chain. Hence, the best possible alternative is to utilize the sewage sludge as a potting media for raising tree seedlings in tree nursery especially timber, energy and industrial wood species. An experiment with an objective of utilizing sewage sludge as a potting media for tree nursery was conducted at Tamil Nadu Agricultural University, Mettupalayam with different potting media mixtures as treatments viz., T1 – Soil + Sand + FYM (1:1:1 ratio); T2 – Soil +Sand + Raw Sewage Sludge (1:1:1 ratio); T3 – Soil + Sand + 2 weeks Composted Sewage Sludge (1:1:1 ratio); T4 – Soil + Sand + 4 weeks Composted Sewage Sludge (1:1:1 ratio); T5 – Raw Sewage Sludge alone; T6 – Two weeks Composted Sewage Sludge alone and T7 – Four weeks Composted Sewage Sludge alone. Eucalyptus tereticornis, Tectona grandis, Azadirachta indica, Casuarina equisetifolia and Acacia nilotica were them grown in polythene bags containing the above potting media. Plant height and collar diameter at two intervals viz., 3 months and 6 months after transplanting and drymatter production at 300 DAT were recorded. The results revealed that the plant height of the E. tereticornis and T. grandis at 3 months after transplanting was significantly higher in T6 whereas the plant height of the other three tree species viz., C. equisetifloia, A. indica and Acacia nilotica was significantly higher in T3. At 6 months after transplanting the plant height of all the tree species significantly higher in T4, T3, T5, T4 and T4 respectively. At 10 months after transplanting E. tereicornis, T. grandis and C. equisetifolia recorded the maximum dry matter in T5 whereas A. indica and A. nilotica recorded maximum dry matter in T7 and T2. Though the sewage sludge is having sufficient major nutrients, it has heavy metals especially, lead, chromium, nickel and cadmium. In this context, the nutrients and heavy metals present in the potting media were analyzed at initial and 300 DAT of seedlings. The results showed that the potting media have considerable quantity of major nutrients and heavy metals also. But the tree seedlings have absorbed the heavy metals from the potting media to some extent. Hence, sewage sludge which has toxic substances or heavy metals could be used as a potting media for raising tree seedlings especially energy, industrial and timber species as they do not affect the food chain. It is concluded that Sewage sludge is an effective substitute to farm yard manure and could be used as a potting media in forest nursery on a large scale.

M P Divya, K Srinivasan and M G Rao
Forest College and Research Institute, Tamil Nadu Agricultural University, India

Wastewater management, including treatment, is vital to protect human health and prevent the contamination of lakes and rivers; but for most developing countries this solution is prohibitively expensive. In such cases, applying wastewater to agricultural lands is a more economical alternative and more ecologically sound than uncontrolled dumping of municipal effluents into lakes and streams, as it offers a form of land based treatment. In rural and peri-urban areas of many developing countries, the use of sewage and wastewater for irrigation is common practice. This is often due to water scarcity but even in areas where other water sources exist, small farmers may choose wastewater because of its high nutrient content, which reduces the need for expensive chemical fertilizers. The use of wastewater in agriculture is thus a form of nutrient and water recycling; and this often reduces downstream environmental impacts on soil and water resources. The outcome of this is improved livelihoods, food security and nutrition for many urban low income households. Despite these benefits uncontrolled use of wastewater may be associated with significant negative human health impacts due to the pathogens contained in the wastewater. Sri Lanka is no exception to this situation and yet wastewater agriculture in Sri Lanka is much less studied than in other countries and is happening unnoticed at present. The objective of this paper is to explore the wastewater use in agriculture in the city of Kurunegala and to suggest the way forward to better wastewater management and reuse.

P Dissanayake and A Clemett,
International Water Management Institute, Colombo, Sri Lanka

Paddy-husk (PH) based deep litter system is the most popular poultry management system in Sri Lanka. Physio-chemical properties of PH make it an ideal litter material for poultry keeping. Since PH is increasingly been demanded by other industries, availability of PH for poultry industry has been restricted from recent years. Objective of the present study was to screen the physio-chemical properties of some commonly available agro-industrial by-products, to be used as alternative litter materials for poultry. Physio-chemical properties such as dry matter (DM), bulk density (BD), pH, water absorbability (WA) and water releasing capacity (WRC) of seven alternatives such as rice straw (RS), coir dust (CD), wood shawing;WS, saw dust;SD, tree litter;TL, shredded paper;SP and refused tea;RT)) were determined and, compared with the respective values of PH. The experiment followed a completely randomized design. The DM % of the alternatives tested ranged from 91% (SD) to 92% (SP). DM contents of WS and RT were statistically similar to that of PH. However, none of the material had either too low or too high DM levels to be disqualified as a litter material. pH values of the tested materials were statistically similar and were slightly acidic (mean 6.27; range 6.1-6.5). PH had the highest BD (0.09g/cm3). The BDs of CD, SD and RT, though were lower than PH, the values were not significantly different from that of PH. WA was also statistically different between the materials. CD had the highest (1101%) WA while RT showed lowest (70%) WA. SD, SP and TL showed statistically similar WA as PH. Materials showed a great variability (from 7.7% for SD to 26.7% for RS) in relation to WRC. PH had 13.6% WRC within 24 hrs. RT had the closest WRC capacity (17.9%) to PH. Materials such as RS, TS, WS and SP showed as high as 25% WRC. When materials were compared for the parameters tested against those of PH, RS and WS were similar to PH only in relation to two parameters. Being comparable with PH for four parameters, SD was identified as the best alternative for PH. CD, TL, SP and RT were comparable with PH in relation to three parameters. Since CD had excessive WA (1101%) and very low WRC it can not be recommended further studies. This study concludes that physio-chemical properties of SD, TL, SP and RT are comparable with PH. Field studies involving live poultry are warranted to determine how birds perform and behave when raised on these litter materials.

N S B M Atapattu, D Senaratne and N D C Sirisena
Departement of Animal Science, University of Ruhuna, Sri Lanka.

In recent years, the demand for coir dust has increased as it is widely used as a growth medium in soil less culture. Since it is low in nutrients, when mixed with vermicompost, will provide a better growth medium for plant establishment. Therefore, this study was carried out to evaluate the properties of different vermicompost and coir dust mixtures. Tomato was used as the test plant and four different media compositions were tested with and without nutrient supplement. Media properties including chemical (N, P, K, Ca, and Mg levels, pH and Electrical conductivity [EC]) and physical properties (Bulk density, Field capacity and drying pattern) were measured in the time period.

Nutrient levels, pH, EC, bulk density, and drying rates were found to be decreased and only field capacity increased with increasing the proportion of coir dust. According to the result obtained, vermicompost alone can be used as a plant growth medium. But poor porosity and aeration of vermicompost limit the root growth and lowered the water holding capacity. Therefore, medium with 75% vermicompost and 25% coir dust is more suitable than vermicompost alone. Medium with 50% vermicompost and 50% coir dust has better physical properties, but nutrient level is not sufficient to support plant growth. Therefore nutrient supplement is needed to use it as growing medium.

B W N Priyadarshani1, S Senarathne2, N A K de Silva2 and W G D Lakmini1
1 Department Crop Science, University of Ruhuna,
2 Agronomy Division, Coconut Research Institute, Lunuwilla, Sri Lanaka

From Proceedings of the International Forestry and Environment Symposium 2006 of the Department of Forestry and Environment Science, University of Sri Jayewardenepura, Nugegoda, Sri Lanka

Chitin is the second most abundant carbon biopolymer on earth, next to cellulose. It is the major constituent in the exo-skeleton of crustacean water animals such as shrimps, crabs etc. Shrimp waste is a major cause for environmental pollution in shrimp cultivating areas such as Puttalam. Current annual shrimp production in Sri Lanka is about 4000 MT and the shrimp waste produced is about 1200 MT. This shrimp waste at present is discharged into environment or buried without any treatment, thereby causing serious environmental pollution problems.

Chitosan, which can be obtained from chitin by chemical treatment, is a polysaccharide of very high economic importance with a wide range of industrial applications. If Sri Lanka can convert its shrimp waste in to chitosan, it can be a major foreign exchange earner, in addition to solving the problem of environmental pollution caused by shrimp waste.

A method for the production of chitosan from shrimp waste using dried papaya milk (DPM) has been developed (Sri Lanka Patent No 13544, 2005). It involves the treatment of demineralised (with 4% HCl) shrimp waste with DPM followed by deproteinization with 3% NaOH and deacetylation with 50% NaOH. The use of DPM brings about a 25% reduction in the amount of NaOH, which is known to cause environmental pollution problems. Typically, the degree of deacetylation (DD) of resulting chitosan was 66% comparable to DD of conventional methods. Moisture content (11.2%) and ash content (0.69%) of resulting chitosan were also comparable to those obtained by 100% chemical methods.

P A J Yapa, A Silva and W T P S K Senarath
Department of Botany, University of Sri Jayewardenepura, Sri Lanka.

The main objective of this study is to develop a porous flexible rubber pipe utilizing the rubber crumb and recycled polyethylene for micro irrigation system to maintain under ground moisture content.

The research work was mainly based on the formula development and the process development. Initially number of formulations based on the plastic binder and vulcanized rubber powder (rubber crumb) and their blends were used. After selecting some useful formulas, process development was carried out based on the temperature settings of the extruder barrels and the mixing characteristics of the blends.

Flexible porous pipe products based on the developed formulas were tested on range of application requirements such as strength properties (tensile & tear strengths), resistance properties (UV, ESCR, chemical resistances), water discharge rate through its wall, pressure existence, durability and density of the product. Results obtained were evaluated to select the most suitable compound composition for porous pipes that yields the best compromise of processability parameters and performance characteristics.

After careful examination of performance applications and quality aspects of the selected product, a process was developed for commercial implementation with a competitive price. As the final product contains fairly high percentage of recycled rubber (rubber crumb) it is going to be one of the major solution for growth of the amount of wasted tire in the environment. The product based on the developed compound composition is fully implemented in commercial scale and expected to introduce to local market and also in foreign market.

N Dayaratna and S Liyanage
Department of Chemistry, University of Sri Jayewardenepura, Sri Lanka.