Microaerobic biodegradation of high organic load wastewater by phototrophic bacteria

High organic strength artificial simulated brewery wastewater (10,000 mgl-1 COD) was used in a batch photo-bioreactor to study the effectiveness of new strain phototrophic bacteria in bioremediation of organic contaminated wastewater. In this work, effects of additions of three individual micronutrients, that is, ferrous, molybdenum and magnesium, and a mixture of micronutrient with urea on the performance of Rhodobacter sphaeroides Z08 in biodegradation of high organic load wastewater undervaried light intensities were investigated. Maximum organic contaminates reduction were 42.3% for ferrous, 36.1% for molybdenum, and 32.3% for magnesium with the corresponding biomass of 989.7, 978.8 and 888.6 mgl-1, respectively. Urea addition increased the wastewater biodegradation potential with the resultant change in carbon to nitrogen ratio (C:N) from initial 200:1 to 200:5. Binary supplement of 26 mgl-1 ferrous and 200 mgl-1 urea to the wastewater readily enhanced the bacteria activity leading to organic contaminates reduction of 67.6%, while optimum pollutants reduction was achieved when binary supplement of urea and ferrous was made under intense radiation of 4000 lumens yielding nearly 80, 48, 90 and 67% reductions of chemical oxygen demand, total phosphorus, total organic carbon and total nitrogen, respectively. In addition, analyses of the resultant biomass and the purified wastewater indicated that major inorganic constituents of the wastewater were assimilated

Prospects of using whole rice husk for the production of dense and hollow bricks

One of the main reasons for the continued increase in the deficit of affordable housing in Nigeria is the high cost of brick made from sand and ordinary Portland cement (OPC). Finding a replacement for cement to assure sustainability is crucial as the raw materials used in making cements which are naturally occurring are depleting. Rice husk was milled and sieved to reduce the size to 0.020 mm. The moisture content of the rice husk was 9.98%, bulk density was 609.61g cm-3 and the ash content was 18.74%. Rice husk was wetted for 3, 6, 9, 12, 15 and 21 h and mixed with slaked lime at the ratios of 1:1, 3:1, 2:3 and 3:2. The composite was molded in cylindrical and rectangular mold using mechanical and hydraulic press. The compressive strength (CS) (N/mm2) was tested at ages of 7, 14 and 21 days. The results show higher compressive strength in 1:1 as the bricks ages and also greater strength when wetted for 15 h. For 15 h wetting, 1:1 had CS (N/mm2) of 2.59, 6.07 and 11.23. If well optimized, rice husk can be an excellent material for brick production thereby presenting a good alternative to OPC.Key words: Hollow bricks, dense bricks, rice husk, compressive strength, molds