Kitchen Best Practices: Reducing Food Solids in Waste Stream

food solids in floor sink

Grease Interceptors collect fat, oil, grease and food particles. While Fat, Oil and Grease get a lot of press and their acronym (FOG), food particles place a central role in the effectiveness of the entire drain line system. Collectively known as food solids, these small bits of rice, corn and grains settle at the bottom of the interceptors. The occurrence and amount of food solids we see in grease traps and interceptors on a daily basis has motivated B Environmental to explain why it’s in the best interests of Food Service Establishments (FSE’s) and other institutions to be aware of food solids and collect them before they go down the drain.

Proactive Maintenance

floor sink

B Environmental specializes in proactively maintaining drain lines in environmentally friendly ways. A core service is monitoring grease interceptors and/or traps, also known as Grease Retention Devices (GRD). Through this service, we’re able to tell our customers exactly how much fat, oil, grease, water and food solids are in their GRD. We recommend that our clients have their GRD’s pumped when total waste (FOG + Food Solids) make up 25% of the GRD volume. To our client’s surprise, the majority have more food solids in the GRD than FOG combined. This means food solids are the waste component that drive pump-outs, and as it turns out, food solids can be easily caught before they go down the drain but rarely are.

GRD’s catch and retain waste. FOG is harder to catch because it’s primarily “in solution” or mixed in the wastewater. Once wastewater has had time to sit and cool, the FOG will separate from the wastewater and rise to the surface. This is the primary function of the GRD. Food solids, by comparison, are easy to catch because they enter the system as a solid. They’re so easy to catch that most kitchen staff think of food solids as an annoyance. As a result, sink strainers, the tool specifically designed to catch food particles, are removed on a daily basis in almost every FSE.

Reduce Risk

With sink strainers removed, food solids can have an adverse effect the entire drain line system. The most common problems are:

  • Increased risk of backups if pump out schedules are not adjusted.
  • Food solids require high flow rates to flush through the drain line system. If food solids don’t move through the system they cause lines to drain slowly and eventually get blocked. This problem becomes more severe if the drain line has a sag or inadequate slope.
  • Pests, such as drain flies, use food solids as source of nutrients as well as a place to lay eggs.
  • GRD effectiveness decreases as food solids collect. When food solids collect in the GRD, the volume available to allow for FOG separation decreases. Over time, the water that enters the waste water system may still contain substantial FOG.
  • Municipalities charge FSE’s disposal surcharges for accepting wastewater based on water quality criteria, including Total Suspended Solids (TSS) and Biological Oxygen Demand (BOD). Food solids adversely affect both criteria and can increase what an FSE will pay for sewer waste disposal.

There are a number of things that FSE’s can do in-house to reduce the food solids load on their systems. B Environmental recommends that FSE’s first talk to staff and explain that removing sink strainers isn’t acceptable. Unfortunately, once habits are in place, it might be easier to change your staff than it is to change their habits. Regardless, it’s important to inform employees of your expectations. Additionally, we recommend metal dome-type strainers, found in floor sinks, be replaced with plastic basket strainers. The plastic strainers have smaller holes which collect smaller material.

Innovative Solutions

fine particle strainer

Additionally, B Environmental offers tools that assists in scrubbing your waste before it goes down the drain. Our Fine Particle Strainer (FPS) collects food particles, as small as coffee grounds, for disposal. Typically installed beneath the pre-rinse station, our current FPS clients average 1 to 7 lbs of food solids removed per day.

An alternative solution, which effectively enforces the use of basket strainers, is our Lock-Down Strainer that locks into the throat of floor sinks. The Lock-Down Strainer has dual purposes. The first is to create a barrier for food and non-food objects that wash into floor sinks while the primary basket strainer is removed. Second, the Lock-Down Strainer will eventually become blocked and staff will have to clean the top of the strainer by hand. Staff will learn it is more effective to utilize the basket strainer than to clear the blockage by hand, reducing food solids from entering the waste stream.

lock down strainer

FSE’s face many challenges in managing their waste stream. Proper solutions to these issues require monitoring and continual focus on best management practices.

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