(33f) Recycling & Garbage - a Separations & Materials Challenge

The field of recycling and garbage is largely overlooked by the Chemical Engineering community and has been the realm of mechanical, civil and even electrical engineers. But there is much to learn and apply in terms of Chemical Engineering from this field. Some surprising facts is that 99.9% of the separations at recycling facilities are done by machines - using the densities and shapes of materials to perform the separation. There are also major opportunities to increase the profit in garbage and recycling through better separation techniques and innovative material applications.

San Francisco has the goal of not sending anything to the landfill by 2020 - only 4 years away. Right now, they are currently around a 70% diversion rate. As the deadline approaches, innovations in this field cannot be just limited to the realm of mechanical engineering. For instance, in the past 10 years, composting technology has increased the amount of materials which are able to be composted. First only yard trimmings were accepted, then food scraps, now San Francisco is able to accept food stained paper products. The ultimate goal of composting is â??anything which was a plant.â?

The garbage stream is also seeing innovations. Earlier this year, San Francisco adopted an organic press, which squeezes all the liquids from the garbage with a hydraulic press. Liquid from the process is sent to a biogas plant to convert into methane & then electricity.

On the recycling side, more materials and separation advances are required to keep the recycling industry afloat.

Currently, the driving force for places where recycling makes sense is areas with not a large amount of space - therefore landfill tipping rates (the cost to dump at a landfill) increase. The Pacific Northwest is home to the highest tipping fee in the nation ($142/ton) and land rich Texas has the lowest at $5/ton. Recycling programs therefore follow the incentives of the state they reside. Diversion from the landfill makes economic sense when instead of paying $40/ton (Bay Area price), separating and giving away material for free. The $40 gap is saved but no profit is made.

The real profit from recycling comes from one material - aluminum. It accounts for 2% of the weight of the recyclate but 40% of the revenue. And paper and plastic are shipped overseas to be manufactured. Advances in material separations and new applications of recycled material is required to make recycling a truly sustainable business model.

Glass is the major loser of recycling. It is such a heavy material so the cost of transportation and disposal is very high. Additionally, remanufacturing options are limited - making new glass bottles is much cheaper than using recycled glass. New, business-sustainable applications of glass are required to make recycling of glass not a losing proposition. Companies are putting recycled glass into concrete and pavement - which is good - but these are not high margin applications. So, glass needs to be and is heavily subsidized by the State of California - which charges a fee to distributors (and then end customers) for glass products.

These opportunities in the garbage and recycling industries are ripe for the chemical engineering community. The focus must turn towards novel applications of materials and advanced chemical separation techniques â?? both well within the chemical engineering realm.