Industrial Pre-Treatment

Introduction

Many of the industrial and commercial activities that we operate or utilize on a regular basis can lead to the production of harmful or hazardous wastes that are classified as contaminants of concern. Substances that are classified as contaminants of concern are any substance that may be harmful to the environment, human health or are made up of high concentration wastes that require extended treatment. In order to continue operating businesses in a manner that will not negatively affect the city and surrounding environment that we call home, these wastes should be contained and disposed of in an environmentally conscious manner.

All locations in the city of Lloydminster that are/will be utilized for the purpose of industrial applications are required to be outfitted with some form of industrial pre-treatment facility. These pre-treatment facilities include Sumps, Oil/Water Separators, or settling facilities. Pre-treatment facilities are the last step to preventing contaminants from being released into the Sanitary sewer system and possibly causing disruptions or issues in the Wastewater Treatment Plant. The types of facilities that should be implemented is heavily dependent on the activities that will be conducted on location and the volumes of wastes these systems will contain.

Maintenance

The Best Operating Practice (BOP) for pre-treatment facilities are to maintain these systems on a regular schedule. In order to determine an adequate schedule, the sump systems should be monitored regularly in order to determine when these systems reach their effective full capacity. In the past operators have waited until their pre-treatment systems start causing problems before maintenance is conducted, which in many cases has already allowed contaminants to pass into the sanitary system. The rule of thumb for the effective full capacity of these systems are 25% of the depth of the system for solids accumulation and 25% of the depth of the downpipe that services the compartment crossover. For this reason the types of wastes that your facility faces the most should be taken into account when determining the length of the downpipe that would work the best for the activities conducted onsite. If your location faces primarily oily hydrocarbon wastes a longer downpipe will be able to contain more of these floating wastes before reaching its effective full capacity. On the inverse side if your facility collects larger volumes of solid and sludge wastes a shorter downpipe would be required to avoid blockages and drainage issues resulting from the accumulation of these wastes.

Most of the pre-treatment systems utilized in the city of Lloydminster have a total capacity of approximately 500 liters but can be as large as 10,000 liters or more for specialized washing facilities. Regardless of the overall capacity of these systems, there will always be a time when the systems reach their effective full capacity and require cleaning and maintenance. The recommended procedure to clean these systems is with a vacuum truck or removal equipment that can remove the floating wastes, settled solids/sludge and the water contained within the system. Removing all of the wastes from the system ensures that it can perform its duty for as long as possible between maintenance activities while also giving an opportunity to check the structural integrity of your system and perform any maintenance required on the system while empty.

The wastes removed from your systems should be disposed of appropriately according to the characteristics of the wastes. The City of Lloydminster landfill operates a wet cell for the disposal of liquid wastes that are not contaminated with oils or hydrocarbons. For the disposal of hydrocarbon contaminated wastes other disposal options should be utilized that can further remove any contaminated solids and liquids from the water and dispose of it accordingly through deep well disposal or into a class 1 landfill.

Guidelines

The City of Lloydminster Wastewater Bylaw (15-2021) requires interceptors to be installed and maintained in any locations where vehicles or equipment may be serviced, repaired, washed or fueled. These interceptors are required on all fixtures and drains that may come into contact with sand, sediment, gravel, oils and/or grease. In this way any drains that release wastewater into the city Sanitary or Storm sewer have some form of contaminant capture facility that removes wastes of concern from your facilities wastewater.

These pre-treatment systems do require regular cleaning and removal of the accumulated wastes in order to keep operating effectively. Under the Wastewater Bylaw it is required to maintain records of any maintenance activities conducted on any pre-treatment facilities in use for a minimum of two years. These records can be in the form of cleaning logs, invoices from third party companies or anything that shows the date and activities conducted to maintain the system. Maintaining these records can serve as reminders to staff of the requirements as well as showing your business’s due diligence in preventing the release of contaminants in the sanitary system.

Figure - Cross section of a traditional sump system. Shown is a two compartment sump, systems with additional compartments would include the same interior plumbing as shown below.

Most of the industrial locations within the city of Lloydminster are equipped with a sump system in shop areas that act as drainage and collection of any water that is released within the shop areas. These systems are generally pre-fabricated concrete pits with steel covers that have built in connections between two to three compartments (as seen in Figure.). In order for pre-treatment systems to effectively contain wastes of concern the system should be equipped with piping on the cross over walls that extends below the water surface. As seen in Figure 1, this piping allows collected oils and contaminants to float on the surface with solids settling to the bottom of the sump; while only the separated water is able to pass through to the following compartment. Without the proper plumbing in place, the floating wastes are the first to pass through the containment wall into the following compartments and finally the Sanitary sewer system.

Preventing Discharge

It is well known that hydrocarbons and oils can cause significant environmental damage if released directly into the environment. This is also the case for the Wastewater Treatment Plant that receives all wastewater released into the Sanitary sewer system, hydrocarbons and oily wastes can cause damages and process upsets within the plant. The Wastewater Treatment Plant that services the City of Lloydminster relies on the use of microorganisms and bacteria to treat wastewater in a ‘Bioreactor’. This Bioreactor was seeded with bacteria and microorganisms from other treatment plants to have the proper varieties required for treatment and maintains an optimal environment for these organisms to thrive. With optimal temperature, pH and aeration the populations of these organisms feed on the organic wastes in our wastewater, the greater the population the greater the volume of wastes that can be processed. Wastes of concern such as oils, hydrocarbons or chemical wastes can be extremely toxic to these organisms and drastically reduce their efficiency, which can be costly to remediate. Even excessive volumes of solids can cause process upsets that can temporarily shut down treatment trains while these solids are removed.

With the population of the City of Lloydminster and all the businesses that call Lloydminster home, every preventative measure taken will help to maintain the efficiency of the Wastewater Treatment Plant. A single liter of contaminants may not be seen as a concern, yet a single liter of these wastes from every household and business can add up to thousands of liters of contaminants in very little time. Controlling and reducing these point source releases can ensure that our Wastewater Treatment Plant can continue operating efficiently and effectively for many years to come.