Compressive and flexural strength of concrete with 30% Crushed Concrete Waste Aggregates (CCWA) and 70% Natural Aggregates (NA) / Mohd Baihaqi Kamaruzzan

Technology in concrete has been developing in many ways to enhance the quality and properties of concrete. From this technology, a lot of concrete were produced and give some impact to the environment such as reduction of raw material, addition in concrete waste, the addition of a waste disposal area for concrete. One of the waste products from construction industry is cube concrete. Cubes concrete have a potential as a course aggregate in fresh concrete. Furthermore, in the future, the amounts of nature aggregate will deficits. This research was carrying out to review the material properties of concrete which the concrete was produced from the crushed concrete waste aggregate (30% of CCWA) and natural aggregate (70% of NA) and to determine the compressive and flexure strength of the concrete. There are two test have been done in order to get compressive strength and flexural strength, which is compression test and flexural test. From the result, at days of 28th we can see that the compressive strength of concrete which mix with 30% crushed concrete waste aggregate (CCWA) and 70% natural aggregate (NA) is lower compared to plain concrete or control concrete

Effect of water parameters on the behaviour of Indo-Pacific humpback and Irrawaddy dolphins in Cowie Bay, Sabah, Malaysia

Many dolphin species around the world are found generally in coastal areas and may be affected by water parameters. Of particular attention are two species of dolphin inhabiting the Cowie Bay on the eastern coast of Sabah; the Indo-Pacific Humpback (Sousa chinensis) and Irrawaddy (Orcaella brevirostris) dolphins. The objective of this study is to determine effects of water parameters (sea surface temperature (SST), salinity and turbidity) on the behaviour (feeding, socializing and travelling) of the two dolphin species. A boat-based survey was conducted monthly from April 2008 to March 2009 (one year) during spring and neap tides. There were 47 surveys conducted for both species. Irrawaddy dolphins were found in 43 surveys (91.5%). The feeding and socializing behaviour of Irrawaddy dolphins were positively correlated with SST and negatively correlated with turbidity. None of the water parameters affected dolphins’ travelling behaviour. The behaviour of the Irrawaddy dolphin was not correlated with salinity. Indo-Pacific humpback dolphins were found only in 41 surveys (87.2%) where its behaviour did not correlate with any water parameters. The socio-economic activities such as logging, agriculture and fisheries highly contribute to suspended sediment and also contribute to high water turbidity in the bay. These are possible causes for the changing of water parameters and may affect the food chain of vast marine life including dolphins. As a recommendation, those activities should be controlled and an the application of sustainable development practices in order to sustain the dolphin population in the bay

A novel study on the effect of rapid biofloc as pellet feed on the survival rate and water quality of mud crab, Scylla olivacea culture

In order to promote the optimum survival rate of mud crab, Scylla sp., in crablet culture, green technology approaches must be developed to increase the yield of mud crab production. The application of biofloc in Scylla sp. culture was proven successful in promoting a good crablet performance and sustaining a good water quality condition. Therefore, due to its importance, this study aimed to determine the survival rates of Scylla olivacea crablets cultured in tanks, fed with pelleted rapid biofloc aggregates. Three feeding trials were conducted consisting of commercial pellet (CP), rapid biofloc pellets (BP) and a mix of rapid biofloc pellets with commercial pellets (BP+CP) and were cultured up to 13 weeks of culture periods. The mud crab crablets were fed twice a day, while water exchanges were only conducted once per week. The survival rates were calculated at the end of the culture period while water quality parameters were regularly monitored. Overall, our findings showed that the survival rate in the BP+CP treatment was the highest with 30%, while 23.3% and 10% in CP and BP treatment, respectively. The water parameter was in optimum range in CP, BP and BP+ CP treatment tanks where pH ranged from 8.19 to 8.26, temperature between 26.68°C to 26.69°C and salinity between 32.17ppt to 33.16 ppt. Ammonium, NH4 + was below an optimum range with, 0.18mg/L in BP treatment and 0.21 mg/L in BP+CP as compared to CP. Meanwhile, nitrite, NO2 - was identified below 1mg/L which ranged between 0.07 and 0.08 mg/L. Therefore, it can be concluded that combination of commercial and pelleted rapid biofloc aggregates have the potential capability to increase the survival rate of mud crab crablet culture while sustaining good water quality parameters and nutrient level

Study on the implementation of different biofloc sedimentable solids in improving the water quality and survival rate of mud crab, Scylla paramamosain larvae culture

Microbial communities in biofloc technology (BFT) are responsible in minimalize water exchange and producing microbial proteins that are beneficial as a supplementals diet for mud crab, Scylla paramamosain larvae culture. Therefore, a study was conducted to determine the effect of bacterial communities in different sedimentable solids in order to improve the water quality and survival rate of S. paramamosain larvae culture. The results successfully identified that the number of pathogenic bacteria, Vibrio spp. decreased when the heterotrophic bacteria thrived in treatment tank with 4 ml/L sedimentable solids. The group of heterotrophic bacteria were able to adapt in developing their population while effectively uptake the ammonium and nitrite components. The ammonium and nitrite level in treatment tank depleting at an early stage of the experiment, and constantly low until the end of experiments (ammonium <0.20 mg/L, nitrite <0.10 mg/L). The survival rates of S. paramamosain larvae in both control and treatment tanks were identified <2.0%, however, sedimentable solids of 2 ml/L was identified suitable to be applied in crab larvae culture as it can help to reach megalopa stages within 17 days of culture period. Overall, it can be concluded that bacteria communities in biofloc are able to regulate nutrients load and maintaining water quality and also help in increased survival rate and development performance in the low sedimentable solids of biofloc culture treatment. Therefore, sedimentable solids of 2 ml/L is suggested to be potentially applied in S. paramamosain larvae cultures from this research finding