By Greg Macdonald
In the spring term at Renison college there are currently only seventeen full time residents. Renison likes to complement these students with conferences and summer courses over the term to bring more people to the college. Over this past term that has included an economic development conference, a Christian nurses conference, two mathematics conferences, English as a Second Languages courses, and spring summer students working on Social Work classes. When these part time residents live at the college they too eat their meals in the Renison cafeteria. However, for this project I am going to concentrate on the food services waste in the spring term.
The Renison college kitchen and cafeteria are open during the spring term. During this term there are only seventeen full time residents, making this the most opportune time to study patterns of waste from Renison's food services. By doing the audit in the summer it is very easy to find time to talk to the kitchen staff, to collect the waste, and most importantly, to least disrupt the daily routines of the kitchen staff for the benefit of my project. I intend to collect the waste coming from the kitchen waste, and from student plates to see patterns of waste disposal in terms of physical weight, type of waste being generated, patterns of waste from day to day, as well as the compostable organic content of the waste to help determine composting feasibility.
Currently, the University of Waterloo, and Renison college have problems with their waste management systems. Budget cut backs have meant less staff and money to be able to study and enact action plans to reduce, reuse, and recycle (compost). That means that the easiest approach for the University and for Renison is to haul away organic waste to be thrown away at local landfills. Currently at Renison college all of the waste created by food services is thrown out. This is very unsustainable. The nature of landfills is that once waste is buried there is little air to reach it. That means that even organic waste can take years to break down. Opening new landfills is a costly procedure that costs millions of tax payer's money to find a suitable site. Even if the new site is deemed appropriate it is impossible to foresee all of the environmental consequences of it.
Another part of sustainablity is closing the loop. By sending our waste off campus it is keeping the system open. It is not sustainable to hope that we can continue to ship our waste elsewhere and assume that we can do this forever. The money that it costs to do this either directly in collection fees paid by Renison or by municipal taxes are all unnecessary if we can reduce that waste ourselves. The money saved can best be put to use supporting education and research, the two main functions of a University. That is why understanding where the waste is being generated, and how much of it is compostable is so important. Unless we have a good grasp on this data, any plan of action coming into place is doing so blind and destined for failure. There is no point enacting a program of waste management and have it stopped after only a short period of time due to inadequate knowledge about the system.
The Renison college food services system is divided into two interconnecting sub- systems. The first is the kitchen, and the second is the cafeteria. In the kitchen there are inputs of raw materials (fresh vegetables, meat, pre-packaged food, etc.), as well as the human inputs of the kitchen staff. In the kitchen the food is processed to prepare it for serving the students. During the processing stage waste is generated in the forms of vegetable and fruit peelings, discarding rotten food, coffee grinds, and packaging. This waste is all disposed of in a dumpster and taken to landfill. The students are the main input of the cafeteria. In the cafeteria there is an exchange of processed food from the kitchen to the students. This includes beverages, soup, salad, deserts, side dishes (usually potatoes or rice), and main dishes. The students then take this food into the dining hall for consumption. After eating the food the students take their trays to the dishwashing area, where the dishwasher scraps everything left on the plate into the garbage. This waste is also sent to the dumpster and then to the landfill.
My goal in the audit was to get the kitchen staff to separate their waste into four sections: kitchen compostables, kitchen non-compostables, student compostables, and student non-compostables. This would be possible by placing a collection bin for compostables directly beside the kitchen garbage, and another directly besides the garbage student wastes are scrapped into. This would make final analysis much easier. It is also important to note that I wanted the kitchen staff to do the separation of waste, not myself. This is mainly because one of the criteria for evaluation is how well the staff separate the waste. To ensure that the kitchen staff understood what I wanted done I had to talk to each one individually about what is compostable and what is not. To aid this I composed two signs, one for the kitchen compostables, and one for the student compostables. Once the kitchen staff were properly trained I could commence with the waste audit.
View the kitchen compostable sign
View the student compostable sign
|Number of Residents||Kitchen Compostables (kg)||Kitchen non-compostables (kg)||Student compostables (kg)||Student non-compostables (kg)|
|Tuesday, June 25/96||17||5.15||4.25||1.2||4.25|
|Thursday, June 27/96||17||1.9||4.75||1.15||3.5|
|Wednesday, July 3/96||17||1.25||6.5||1.05||5.45|
|Thursday, July 4/96||17||3.8||2.4||1.9||2.6|
|Monday, July 8/96||34||5.85||6.15||2.1||5.55|
|Wednesday, July 10/96||34||4.1||2.6||2.2||6.5|
|Monday, July 15/96||34||3.3||14.4||2.2||5.2|
|Tuesday, July 16/96||34||3.5||4.1||2.1||6.05|
The graph above shows that 39% of the waste coming from Renison's kitchen is compostable, while 61% of the waste is non-compostable by weight. This data includes all eight sample days as actual weights are not what is being measured just composting percentages. These results are very interesting as 39% is a lot of waste that could be reduced by composting. The compostable waste is made up of vegetable peelings for the salad bar, soup, and vegetable side dishes, rotten fruit, eggshells, and coffee grinds and filters. The Renison salad bar is kept fully stocked with lettuce, cucumbers, tomatoes, potato salad, carrot and celery sticks, broccoli and cauliflower, spinach, brussel sprouts, and macaroni salads. These salads must be kept full and accordingly peelings are created every day. Renison also puts out an assortment of fresh fruit such as apples, oranges, and bananas. If any of this fruit is not taken before it goes bad it was dumped into the compost bins as well. Peelings for side dishes are not as regular as Renison may peel carrots on one day for the entire week. The potato peeling machine is also only cleaned out when it is full and thus this weight is only periodically reflected in the data.
The waste that is non-compostable from the kitchen was usually non-organic in nature. This included plastic milk containers, cereal containers, and napkins. Periodically, meat that could not be used again was also thrown into this garbage. I am very pleased with the results of the kitchen audit. There was no contamination of the kitchen compostable bin, any only once were compostables thrown out accidentally. The potato peelings were once thrown into the regular garbage and due to their mushiness could not of been transferred to the compost bin. It is important to note that the staff had no problems in separating the waste. Since the compost bin was located directly by the garbage where waste is normally put it took no extra time to separate it. Another factor involved in the high compost percentage is that most leftover meat is reused into stews. Leftover vegetables are also recycled into Andy's soup of the day, and stews.
This data is also very interesting in that the percentage of compostable waste has reduced dramatically when compared to the kitchen. Only 26% of student waste is compostable, with 74% being non-compostable. This is a 13% drop in compostables. I initially expected student compostables to be easier to compost and separate. For this site the staff scrap any compostables into the compost bin and the rest into the garbage. I believe the biggest reason for this drop in percentages is the avoidance of contamination. I was very explicit with the kitchen staff that any vegetables contaminated with gravy, oils, butter, or fats be thrown into the garbage. Despite the fact that many residents don't finish all of their vegetables most of the leftover vegetables such as cooked carrots, beans, or peas are usually contaminated with sauces from the main dish. While this may seem unfortunate it is much better to get an accurate account of what should actually be composted than artificially boost that number with contaminated vegetables that would attract pests to a composter.
The student compostables thus included mostly fruit peels from breakfast and lunch. It is very easy for the staff to put a half grapefruit rind or melon rinds in the bin than to separate contaminated from compostable cooked carrots. This means that almost without exception all of the student compostables is fruit from breakfast or lunch. Non- compostables are almost entirely organic in nature. This includes any meat scrapings, dairy products, desert leftovers, and used napkins. While this result may seem initially disappointing they may actually be advantageous. Due to the ease of collecting the fruit rinds I am inclined to forget about putting out composting bins at dinner, and only collect student waste at lunch and dinner when a composting program is initiated. This is important as the staff expressed worries about not having the time to separate student waste during the fall and winter as the number of students is so increased. I also don't feel the composter would be overrun with acidic fruit as the kitchen waste is primarily vegetable in nature.
When looking at the overall results of composting percentages it is found that 34% of the waste being generated from Renison's food services is compostable. A side note on that figure is that 60% of that compostable waste is from the kitchen while 40% of the compostable waste is from the students. Again, that is due to the high contamination rate of compostables from student plates.
The graph above shows the wave pattern of compostables day to day. The results roughly show the cyclical pattern of more compostables on Tuesday and Thursday, and less compostables on Monday and Wednesday. There are many possible explanations for that change. I can hypothesis that the kitchen staff peel enough vegetables for the salad bar and side dishes for two days. That is shown in the data as I noticed an exceptional amount of vegetable peelings in the kitchen compostable bins on Thursdays. Another possible explanation is that there may of been simply less non-compostable waste on those days. This however is harder to provide reasons for as most non-compostable waste is generated randomly (i.e. whenever the milk runs out the bag is thrown out). Even patterns of the menu could affect this data. If watermelon was put out on those two days that would result in an increase of compostables in the student area. All in all there are so few sample days and so many possibilities that it is hard to pin point concrete explanations for these results.
I don't believe that either method is totally valid. I don't think it can be assumed that waste increases at a constant rate because there is a base amount of waste that is created just for keeping the salad bar stocked and that would not be reflected for each increase of 34 students. The law of exponential growth is also not exact as with only four sample periods at both 17 and 34 residents there is too much room for error. An example here is that preliminary comparisons before the last two audit days were complete showed only an increase of 15% as you go from 17 to 34 students, not 33% as indicated above.
Either way, some base conclusions can be made from the data. Using 95kg /day/ 170 residents results in 32.3kg of compostables per day (95 x .34). Using 128kg / day /170 residents results in 43.52kg of compostables per day (128 x .34). For the composting program I have planned at Renison, a 3-bin turning unit is the most appropriate choice. This type of composter is the fastest and largest of the backyard styles. It can handle up to 20kg of compostables per day. Using the results of the audit, I predict that Renison would produce more than that amount. However the data above does not reflect that approximately 30% less students eat at Renison on Fridays and on the weekend. That would result in a noticeable decrease of the average daily compostables.