ABSTRACT:In this study, Polypropylene (PP) plastics waste with various concentrations of 0.5%, 0.8%, and 1% were investigated to substitute bitumen's mass. The mixing of plastics and asphalt was conducted by wet method, which added PP plastic into the asphalt when being heated so it produced a homogeneous mixture. Then, AC-WC mixture was made with bitumen contents of 5%, 5.5%, 6%, 6.5%, and 7%. Each mixture was carried out in triplicate for every plastic's concentrations. Five parameters of mixtures were tested by Marshall Method, as follows: VIM, VMA, VFA, stability, and flow. Then, all the parameters were plotted in bar chart to determine an OBC (optimum bitumen content). Changes in rheological properties after the addition of PP plastics occurs which indicates the increasing of viscosity, softening point, flash point, and the decreasing of density, penetration and solubility. Based on Marshall Test, the OBC for asphalt pen 60/70 was 5.4% while the OBC with PP plastic content of 0.5%, 0.8% and 1%, consecutively, were 5.41%, 5.43% and 5.45%. Despite the increasing of OBC, this substitution of bitumen to plastics has some advantages such as increasing stability and remaining strength index (RSI), reducing plastic waste generation and asphalt cost. However, it has disadvantages such as it consumes more energy and it increases gas emission.
Conventional active sludge is the technology that is usedcommonly in wastewater treatment. However, this technology has thedisadvantage, its relatively low settling speed causing a large landrequirement. One technology that can be used to overcome this deficiencyis aerobic granular. In this study aerobic granular is formed in acontinuous flow system of airlift reactor with a 12 (twelve) hourshydraulic retention time. Aeration is carried out for 24 hours at a rate of 2liters per minute (lpm). The height variation of top clearance (ht) is usedto determine its effect on the aerobic granular formation. The ht variationused is 15 cm, 20 cm, and 30 cm. The height of top clearance at the airliftreactor affects the circulation and superficial gas velocity which thenaffect the hydrodynamic shear force. The larger the hydrodynamic shearforce, the better the granular quality will be. The granular quality isdetermined based on physical characteristics including Sludge VolumeIndex (SVI), sludge density index (SDI), settling velocity, size, and aspectratio. The result shows that the height of top clearance affects the granularquality that formed. However, the effect is not linear. The non-linearity ofthe relationship between the top clearance height and granular formationcan be due to the sizeable superficial gas velocity and biomass washout. The ht variation that provides the best granular quality is achieved at 15cm, followed by 30 cm, and finally 20 cm. The ht variation of 15 cmreaches an optimum result with the value of SVI is 50 ml/g, settlingvelocity 39,4 m/hour, SDI 2.02 g/ml, size 3.5 mm, the aspect ratio of 0.86, and organic removal efficiency reaches 87.2%.
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