Environmental Engineering

Urea Super Granule (USG) application in paddy filed is an innovative technology to reduce the nitrogen fertilizer losses in the field. The best model among the available USG applicator was selected and modified it to improve the performance. In the field test, with USG size of 2.7 gm, effective field capacities of the improved applicator and the BARI model were found 0.154 ha/hr and 0.147 ha/hr, respectively. Similarly, with USG size of 1.8 gm, the effective field capacities of improved applicator and BARI model were found 0.146 ha/hr and 0.144 ha/hr, respectively. The missing rate, holding more than one USG per cup, breakage & dust formation of BAU model were found 1.83%, 0.61% and 2.63 %, respectively in case of USG size of 2.7 gm and 1.22%, 3.05% and 1.5%, respectively in case of USG size of 1.8 gm. On the other hand, the missing rate, holding more than one USG per cup, breakage & dust formation of BARI model were found 12.8 %, 6.71% and 7.93 %, respectively, in case of USG size of 2.7 gm and 10.97%, 9.76% and 6.5 %, respectively, in case of USG size of 1.8 gm. Most of the indentified problems of BARI model have been solved and the improved version of USG applicator(BAU model)may be accepted for demonstration and dissemination in farmer field.

The study was carried out through interviewing of one hudred farmers in two villages of Mymensingh Sadar Upazila, Banglades\ during the period of Jan-May,20ll to assess the availability and utilization of energy from different sources at household level. The oornmon sourc€s of biomasses are wood, tree twigs and leaves, crop residues, jute sticks, rice huslq rice sEaw, cow dung, etc. and constitute about 60% of total energy consumption in rural households. The total €nergy consumption vras found to be (350-500) kg/month according to the sizes of family. The share of non commercial €nergy sourcers i.e. cow dung, tree leaves, rice husk, jute sticks, crop residues varied from (85-95)% and commercial sources i.e. electricity & kerosene contributed (5-l0)% energy. Energy saving technologies should be encouraged for efficient use of available biomass in the country. Biogas plants, improved cooking stoves, biomass were such efficient technologies. These technologies need to be standardized and encouraged for dissemination at nrral household levels in Bangladesh. However, many households may need financial srryport for owning these technologies. The Government along with NGOs and private sector instihrtions should initiate programs for extension and dissemination of these technologies.

The fluidized bed drying principles for drying of tea in Bangladesh is thoroughly studied. The experiments were conducted to determine the drying curve, drying time, drying constant and dynamic equilibrium moisture contents of tea at the Bangladesh Tea Research Institute. Drying of tea in a fluidized bed dryer (Kilburn Vibro Fluid Bed Dryer) takes only 20 min for drying from an initial moisture content of 69.1% to a final moisture content of 2.8%. Temperatures of drying air were recorded to be 130°C at the inlet and 90°C at the outlet. The drying constant was found to be 31.05 h -1 and the dynamic equilibrium moisture contents were in the range of 18.3 to 2.0%. Finally the principle of fluidized bed drying was compared with the principle of conventional endless chain pressure type drying.

An attempt was made to design a low cost floating house suitable for people in low lying areas such as Bangladesh. The prototype house considered for the present study has the carrying capacity of 1850 kg loads with sufficient freeboard of 30% excluding the self weights of the supporting ten airtight empty steel drums in water and having a floor area of 120 ft2. These steel drums that are locally available and provide an atmosphere to live in without the fear of losing possession during flood. The value of metacentric height (10.22 ft) of the designed house was found to be positive indicating its stability at floating condition. The angular displacement of the house due to wind action was also calculated and this floating structure would be stable up to the wind speed of about 160 km/hr. To provide sanitation a floating toilet can be hinged with the structure. It would definitely give an eco-friendly out look to the structure. For variable fencing, flooring, roofing and floating elements costs were estimated to determine the most economic feasibility. The most economic house was supposed to be made of locally available materials such as chhon and golpata. But from the engineering point of view the most stable and durable house was found to be CI- sheet and angle bar. Above all, the house made of Bamboo could be used on the basis of availability and durability. This house could be used all the round year as a permanent address for landless people and gypsies.