Plastic Waste Segregation Machine Using Sink Float Method

ABSTRACT

Today, economic growth and changing consumption and production patterns result a rapid increase in generation of waste plastics in the world. According to studies, the world’s annual consumption of plastic materials has increased from around 5 million tonnes in the 1950s to nearly 100 million tonnes, thus twenty (20) times more plastic is produced today than 50 years ago. This is an implication of using more resources to meet the increased demand of plastic while generating more plastic waste. Having this implication, the research team designed and fabricated a machine, segregating plastics out of mix waste from CIT-University. Based on research, around 30% of the garbage collected inside the campus is plastic waste. This is essential to develop a plastic-waste separating system that would help the promotion of recycling plastics and in order to avoid environmental deterioration through reusing materials whose composition enables their recovery.

The system is composed of a feeding tank, feed crusher, and a separator tank. The process is done by separating plastics from waste materials which contain at least partially reusable elements, mainly papers, plastics metals etc. The waste materials are stirred in water through mechanical forces where large sizes are reduced. The metallic elements are separated from the suspension as heavy materials. The remaining coarse solids, in particular plastics, are mechanically separated from the suspension, and the suspended fine solids are separated from the suspension by dewatering. A method and apparatus are provided for separating mixed plastics using flotation techniques including a first stage initial washing tank for washing of incoming plastics and providing a first separation process and a separation module. The separation module includes a separation tank, a feeding section for feeding of mixed stream into the separation tank, and a collecting section for collecting of the separated mixed plastics including floaters and sinkers from the separation tank. The separation tank has no moving parts. Batch processing is replaced with generally continuous operation.

1.1     Introduction

1.1.1  Rationale of the Study

CIT-University, a prestigious school in Cebu City, is faced with an increasing rate of waste generation. It generates from 28 to 32% plastics, amounting to more or less 0.5 tons plastic of about 1 ½ tons of waste a day. The school administration needs to be able to gather all stakeholders, define their specific roles, and encourage them to do their share in the ecological management of waste. It also needs to access required resources from other local school that provide funding window for a comprehensive and integrated Solid Waste Management system. Recovery of waste plastics is relegated to the informal sector depriving the city of an abundant resource that could be converted into fuels. Policy on solid waste management is quite comprehensive, although there are no specific regulations on the utilization of plastic and its consequent waste products. Aside from this gap, other areas that should be addressed by appropriate policy are recovery, recycling and utilization of waste materials, including plastics. The Renewable Energy Act encourages waste to energy conversion and provides incentives for such infrastructure. Cebu City is blessed with a vibrant NGO community doing complementary work on community based waste management. It also has a proactive commercial and industry sector engaging in various initiatives for the environment, particularly solid waste. However, majority of household waste generators dispense their responsibility to the LGU. Their support, especially in the areas of source reduction, source segregation and primary recovery will be crucial in implementing any SWM system, program or project.

1.2.3           Scope and Limitations

The plastic waste segregator machine is designed and fabricated to separate plastic waste out of mixed waste generated from CIT-University campus. These mix wastes are composed of papers, plastics, and leaves. There is a pre-segregation process conducted first manually before the plastic waste segregation is introduced.  

After fabricating the machine, the researchers conducted several tests on the plastic waste segregator machine. The following are the lists of several observations obtained by the researchers during testing:

1.    The power generated by the motor is not sufficient due to friction losses in the system as it operates.

2.    After the operation, there is a size reduction of waste happen but of unequal sizes.

3.    The machine cannot operate a long hours of continuous operation.

4.    The actual feeding tank used is not appropriate to the desired tank design due to its irregularity of the bottom surface of the tank since the effective and efficient way is to make it plain.

5.     The motor cannot handle the required power of the cutting blades to rotate because of the presence of the water which adds resistance during operation.

6.    The diameter of the discharge pipelines is too small that cannot accommodate waste of large sizes.

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