waste materials
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Abstract Geopolymer concrete is concrete that uses environmentally friendly materials, using fly ash from waste materials from the coal industry as a substitute for cement. To produce geopolymer concrete, an alkaline activator is required, with a mixture of Sodium Hydroxide and Sodium Silicate. This research is an experimental study to determine the effect of variations in the concentration of sodium hydroxide (NaOH) 8 Mol, 10 Mol, 12 Mol, and 14 Mol on the compressive strength of geopolymer concrete. Mortar Geopolymer uses a mixture of 1: 3 for the ratio of fly ash and sand, 2.5: 0.45 for the ratio of sodium silicate and sodium hydroxide as an alkaline solution. The specimens used a cube mold having dimension 5 cm x 5 cm x 5 cm, then tested at 7 days and 28 days. The test resulted that concentration of NaOH 12 Mol obtained the maximum compressive strength of geopolymer concrete, that is 38.54 MPa. At concentrations of 12 Mol NaOH and exceeding 12M, the compressive strength of geopolymer concrete decreased.

Abstract In this study, we investigated the proline and protease production of different bacteria in several organic waste materials. Our aim was to produce proline and protease economically in waste that is abundantly available while reducing its environmental impact. 5 ml of different organic waste materials (OWW: Olive waste water; N.B: Nutrient Broth; EW: Eggshell; PBS: PBS buffer; PLW: Peach leaf wastes; TCW: Turkish coffee wastes; TWW: Tea waste water; WCW: Waste cheese whey; WFO: Waste frying oil) were placed in 10 ml grow tubes, inoculated and incubated for 24 h. Phosphate-buffered saline and 10% solutions of different organic wastes were added. These cultures were subsequently incubated at 37°C for 24 h. Cells were harvested at 24 h for L-proline assay. 1 ml of culture was transferred by pipette into an Eppendorf tube and centrifuged at 14,000 rpm for 20 min at room temperature. Cellular debris was removed by centrifuge and the supernatant was used for proline activity assays. Protease activity was determined using a modified method with casein as the substrate. We found that proline and protease can easily be produced economically using Turkish coffee wastes (TCW), Waste cheese whey (WCW) and Olive waste water (OWW) organic waste. We believe that this study will result in similar research leading to the economical use of these waste materials thus reducing their impact on the environment.

Most of the waste materials recycled for the production of new construction materials are by-products of various manufacturing processes, such as the aggregate washing process. Recycling such materials is of paramount importance since it could reduce the adverse environmental impacts resulting from landfilling. Various studies have attempted to recycle different types of waste materials and by-products into concrete paving blocks. However, the availability of literature on concrete paving blocks containing waste silt is quite scarce. Thus, the current paper focuses on mix design optimization and production of concrete paving blocks containing high amounts of waste silt resulting from the aggregate production process. Using the mixture Design of Experiments (DOE), 12 sets of concrete paving blocks with different aggregate blends were produced to optimize the mix design. Once the final mix design was achieved, the physical and mechanical properties of the concrete paving blocks were investigated following the EN 1338 standard. Shape and dimension measurements and various tests, including water absorption, tensile splitting strength, abrasion resistance, and slip/skid resistance were conducted on the experimental concrete paving samples. Overall, the produced concrete paving blocks showed promising properties for future applications in pedestrian walking paths.