Recycling collection/cleaning/separation

Recycling of postconsumer plastics involves the process of collection, cleaning, separation, and then processing them into various products. These different steps will be elaborated in the following sections. 

The purity ot the scrap mainly determines the fraction of energy needed to produce metal from it, and the value of recycling. Clean copper scrap need only be remelted and cast to form recycled copper if the copper is contaminated with organic materials and other metals, more complex separation processes are needed that are similar to production from ores. It is easier to remelt the steel of a car driven in Arizona compared to one rusted by the road salt in snowy areas. Scrap that is produced as a by-product of metal processing can be easily recycled, and it can be collected from relatively few locations. There has been a strong effort to educate both householders and industrial users to separate scrap and return it to waste collectors, leading to a supply of reasonably separated scrap. 

Separate collection of plastics, sorting, cleaning and mechanical recycling. 

To get some idea of the prices to be expected for compounds produced with these approaches, we have estimated the total cost of producing 10,000 tons per annum of 1-octanol from w-octane, based on data collected for this conversion by P. oleovorans, during growth in a two-liquid-phase system containing 15% (v/v) hexadecane as a carrier phase. n-Octane is dissolved in the carrier phase to a concentration of 5-10% (v/v), converted by the P. oleovorans cells in the aqueous phase, and the product 1 -octanol dissolves in the hexadecane phase once more. Downstream processing consists of a phase separation, followed by two distillation steps. In the first step, the C8 alkane/alkanol are separated from the hexadecane, which is recycled into the bioreactor. In the second step, the w-octane is distilled off the n-octanol the octane is recycled to the bioreactor, and the octanol is collected as the desired product. This approach leads to a very clean product stream of >98% pure 1-octanol. ... 

Individual drums are provided for each product fraction. A detector monitors the separation and provides signals for controlling the injection and collection sequence. The operation of partial condensers for the dilute eluted streams presents challenges because of aerosol formations. When a valuable carrier such as nitrogen is used, it must be cleaned up and recycled. 

At this point, switch to recycle by turning valve 1 and 2 at the same time switch valve 3 to waste. We want to send the contaminated portion between peaks back through the pump head back to the column head for further separation. We continue to recycle until the detector shows we are well down on the backside of peak B. (Remember, A is tailing into B.) Change the collection flask while we are recycling to collect flask 2. Shut recycle valves 1 and 2 and switch valve 3 to collect in flask 2. Stop collecting 2 when we reach the baseline on the recorder and switch valve 3 back to waste and change to a clean collection flask 3. 

Because these temperatures are impractical, the thermochemical water-splitting cycles achieve the same result (i.e., separation of water into hydrogen and oxygen) at lower temperatures. A thermochemical water-splitting cycle is a series of chemical reactions tliat sum to the decomposition of water. To be useful, each reaction must be spontaneous and clean. Chemicals are chosen to create a closed loop where water can be fed to the process, oxygen and hydrogen gas are collected, and all other reactants are regenerated and recycled [2]. 

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