Tag: compost

Composting at Home

Author: Claire Wayner ’22

Stuck at home and tired of your garbage can getting stinky? A full 22% of your trash (or more) is likely food, and food waste doesn’t smell too great after a couple of days. There’s an easy and environmentally friendly solution to the odor – start composting! 

By breaking down the food in combination with leaves and water, the process yields a rich, nutrient-filled soil additive called compost that can be used in your home garden beds or gifted to your neighbors (here is an article on the benefits of compost for your garden). Composting at home is really easy to start up and doesn’t require a ton of resources. My family has been composting since I was in middle school, and since then, we’ve learned a lot of helpful tips which I’ll share with you below.

During the day, we collect our food scraps indoors in an old yogurt container in the fridge to prevent it from smelling up our kitchen counter. We then empty the scraps into our outdoor composter whenever the indoor container is full. Our outdoor composter is a tumbling, elevated version which we keep in our backyard. It’s definitely worth the investment to buy a model like the one we have because it keeps food scraps contained and elevated (to prevent us from attracting unwanted pests like rats, as we live in a city) and also makes it easier to regularly turn the compost (moving the scraps around is important to promote breakdown and aeration). You don’t need a shiny new container to start composting, however. In a pinch, you can build your own out of anything from milk crates to recycled lumber. 

Home compost collected in an old yogurt cup
Photo Credits: Claire Wayner

Keep in mind that you can’t compost all of your food scraps at home – things like dairy, meat, prepared foods/dishes, and disposables marked as “compostable” should stay out of your home compost, as they won’t break down unless put in a more industrialized composting environment like Princeton’s S.C.R.A.P. Lab. Stick to things like fruit and vegetable scraps, eggshells, coffee grounds, or clippings from your yard (raked leaves in the fall are great!). Try to get your ratio of “greens” (e.g., grass clippings, fruit and vegetable scraps) to “browns” (e.g., leaves, eggshells) right.

There are plenty of tutorials online on how to get started (check out this one from NPR). If you live in a dense city and can’t easily set up a compost bin, there are always countertop composters for apartments, or you could check to see if your municipality offers curbside composting pickup (ShareWaste has a great directory of where to drop off your compost if you can’t use it in your home).

Elevated, tumbling outdoor composter
Photo Credits: Claire Wayner

By starting to compost, you can make a big difference. Most greenhouse gas emissions from landfills come from the breakdown of food. Composting can reduce these greenhouse gas emissions and give us a usable product at the end of it. 

Bringing Together Algae, Food, and Compost

Author: Wesley Wiggins ’21

In the Fall 2019 semester, I worked on a project which incorporated the S.C.R.A.P. Lab (our campus composter, fondly known as Scrappy) for my class ENE321: Resource Recovery for a Circular Economy taught by Civil and Environmental Engineering Professor Z. Jason Ren. This class discussed the topic of a circular economy which is the idea that resources should be reused and repurposed instead of how our linear economy simply puts items into waste. Our final project for this course was to create a business idea and pitch for a company that incorporates elements of the circular economy, and when I first heard of this idea my mind immediately turned to compost. 

Composting takes food scraps and uses it to create a soil additive that enriches the earth which can assist in growing new food and/or keeping the environment healthy. My team also wanted to incorporate a new element and produce something from compost. Through our research, we learned that the process of composting emits biogenic CO2 and we wanted to repurpose that gas and produce something new. Our minds turned to the process of photosynthesis in which water and carbon dioxide contribute to building organic matter so we wanted to find a product that we could grow easily and then sell to consumers. This is when we came across the algae species, Arthrospira maxima and Arthrospira platensis more commonly known as Spirulina.

Spirulina (Arthrospira platensis and Arthrospira maxima) contains 55-70% protein by dry weight, as well as high amino acid content and nutrients. It grows best in environments with high CO2 concentrations, a high pH, and high temperatures.

Spirulina are a globally cultivated algae species for food production because of their high protein content and nutritional value. We decided that the nutritious algae would be an excellent food product to sell as our business product and the only thing left to decide was how to grow the spirulina. We decided that the best way to grow them and incorporate the compost would be to use a photobioreactor which is a closed system that would allow us to control the inputs and outputs of the spirulina growth mixture. We could also take the CO2 from an industrial composter like Scrappy and feed it into our photobioreactor to cultivate the spirulina.

After settling on an idea, my team had to settle on a company name and company roles. The members of my team were myself as the Chief Technological Officer, Jivahn Moradian ‘20 as the Chief Financial Officer, and Gabby D’Arcangelo ‘21 as the Chief Executive Officer. When deciding on a name we wanted something that represented both the algae and the use of carbon dioxide from the composter. So the name we settled on was AlgaeHG or AlGHG. The GHG in the title is short for Greenhouse gases which we are using to create our product in the form of CO2.

Gabby D’Arcangelo ‘21, Wesley Wiggins ’21, and Jivahn Moradian ‘20 (from left to right) presenting the AlgaeHG business pitch and presentation in ENE321: Resource Recovery for a Circular Economy.
Photo Credits: Professor Z. Jason Ren

Though the company was created for a class project, the three of us had quite a fun time brainstorming the science, engineering, finances, and algae puns for our little class project. And we were thankful to Gina Talt and the S.C.R.A.P. Lab for letting Gabby and Jivahn visit the Lab during my shift, and for all of the other assistance, we were able to receive.