City’s Wastewater Infrastructure Upgrades

August 5, 2021 | 0 Comments

The City of Hamilton announced that it “will invest in major upgrades to the City’s wastewater infrastructure that will prevent approximately 1,210 litres of ‘solids’ per day from entering the ocean.”

A spokesperson said, “The City has plans to purchase two fine-mesh screening machines which will be installed at the Front Street Wastewater Treatment Plant and will remove approximately 40 per cent of suspended solids from the City’s wastewater.

The City’s New filtration system: Salsnes Filter SF 6000

City Invests In Wastewater Infrastructure Upgrades Bermuda Aug 2021 1

“The implementation of this two-stage screening system will also lead to a significant reduction in the amount of macro and micro plastics entering the ocean at the South Shore outfall. These plastics can enter the sewer system through incorrect disposal of plastic materials, through the use of personal care products containing micro-beads, and through the laundering of clothing containing plastic fibers, such as polyester.

“The City will also commence a peracetic acid [PAA] disinfection process on the wastewater prior to it being expelled through the Seabright outfall; this will significantly reduce the levels of bacteria in the effluent, thus further safeguarding the quality of our bathing water which is already within regulatory standards.

“PAA is a clear, colourless liquid, with a pH of less than 1 with non-toxic byproducts, making it safe for the environment with essentially no harm to coral reefs or aquatic life. It has been used at numerous wastewater facilities in coastal areas in Europe for protecting water quality used by recreationalists. As the use of PAA disinfection can be costly, it will only be carried out during bathing season, from April through October.”

New City wastewater screens will stop a ‘dumpster of solids a day’ from entering outfall. City Engineer Patrick Cooper is pictured with a dumpster of comparable size.

City Invests In Wastewater Infrastructure Upgrades Bermuda Aug 2021

“The City of Hamilton and the surrounding area has been serviced by a community sewerage system, discharging to the ocean off the South Shore, for over 100 years,” explained City Engineer Patrick Cooper.

“Over that period of time, several upgrades have been made to improve the system. Most recently, in 2015 the City carried out a refurbishment of the existing wastewater filtering screens from 6mm to 3mm perforated plates, preventing any solids more than 3mm in size from being discharged from the outfall.

“This was partly in response to the infrequent but unpleasant appearance of ‘greaseballs’ washing ashore on beaches near the outfall during that time, caused by rare and short-lived seasonal conditions [such as abnormal winds and currents].

“The two new screens we will install are even more restrictive against solids, preventing anything over 0.35mm from passing through them; there will be no bits or lumps, just liquid, which will further decrease the incidence of greaseballs forming along South Shore.

“Once we get these new screens installed, they will prevent 1,210 liters of solids per day [based on a 40% solids capture rate using an average annual flow rate] from going into the outfall; this is essentially a large dumpster of solids a day.”

“The City of Hamilton implemented its Fats, Oils and Grease [FOG] Policy in 2014 which requires commercial good establishments to properly dispose of their FOG and install grease traps which are regularly checked by Government and City officials. The Government of Bermuda then implemented related health regulations in 2017 based on the City’s policy.

Mr. Cooper said the FOG Policy had led to a major improvement in the amount of grease reaching the Front Street Wastewater Treatment Plant: “Prior to implementing the FOG Policy, we were removing grease from the plant four times a week; now, we only have to remove grease once every two weeks. The City collects approximately 5 tons [or 10,000 gallons] of waste cooking oil per week.”

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