Sludge Watch ==> Sewage 101 - Stephen Salter - British Columbia

[Maureen Reilly]

Sewage 101



 Brennan Clarke/Victoria News
Environmental engineer Stephen Salter says sewage-treatment technology like 
the 35-year-old secondary treatment system on the Tsawout Indian Reserve is 
ancient technology, yet the Capital Regional District seems unwilling to 
explore more advanced options.

By Brennan Clarke Victoria News
Sep 29 2006
Stephen Salter stands on a sunny rock outcrop overlooking the Gulf Islands 
just north of Island View Beach, a world class vista in the background, a 
huge, bubbling vat of raw sewage in the foreground.
Located on the Tsawout Indian Reserve, the vat is the centrepiece of a 
35-year-old secondary sewage treatment plant that was transferred to the 
band in 2002.
To Salter, an environmental engineer by trade, the Tsawout facility is a 
dinosaur, an age-old relic rendered obsolete by new, eco-friendly 
technology.
"We can do much better than this," he said, noting a slight whiff of 
effluent in the air.
"Primary treatment was leading edge when it was first developed around 1900. 
Secondary treatment was developed in 1914. Modern processes would be 
entirely enclosed. In my view it's a complete waste of time."
That view isn't shared by CRD staff. A recent request for qualifications 
advertised earlier this month asked prospective sewage treatment providers 
to weigh the merits of "providing primary treatment initially, followed by 
secondary treatment in, say, 10 to 15 years, compared to providing secondary 
treatment initially."
The RFQ was the CRD's first move following Environment Minister Barry 
Penner's recent decree that the CRD revise its sewage treatment plan by June 
30.
As local politicians debate the merits of various options, Salter is 
diligently lobbying elected officials to design a system that uses "green" 
technology.
To most people, sewage is something to be flushed and forgotten.
For Salter, it's a renewable resource that can yield water for irrigation, 
grease that can be converted into bio-fuel, methane that can be burned to 
generate electricity and nitrogen-rich sludge that can be used as 
fertilizer.
"It's about changing the way we look at sewage treatment," he said. "It 
changes the community planning when you think of it as a resource."
Salter spoke to Esquimalt council last week. On Sunday, he's off on a 
fact-finding mission to Gothenburg, Sweden, home of "the very best" sewage 
treatment plant in the world. Later this fall, he'll include that 
information in addresses to other area municipalities.
The Tsawout treatment plant, about as basic as they get, isn't designed to 
recover resources. It's a holding tank containing bacteria that, when fed 
oxygen, digest the bio-solids suspended in the effluent. The sludge that 
settles to the bottom is collected, dehydrated and either trucked to the 
landfill or, if required permits are in place, spread on a farmer's field.
"The water just goes out to sea and anything else in the water goes with 
it," Salter said. "There was no resource recovery intended."
The region's only other sewage plant, opened in 2002 near Bazan Bay on the 
Saanich Peninsula, takes treatment one step further, removing 90-95 per cent 
of solids from piped-in liquid effluent.
The most common form of secondary treatment, the Bazan Bay system uses a 
primary settling pond along with an oxidation ditch where oxygen-fed 
micro-organisms process the effluent.
The well-fed organisms eventually die and fall to the bottom of the vat, 
taking most of the suspended bio-solids, heavy metals and other contaminants 
with them.
Like Tsawout, the water is then pumped into the ocean and the sludge trucked 
away.
Everywhere else in Greater Victoria, raw, unprocessed sewage is diverted 
directly into the ocean.
Environment Minister Rona Ambrose's announcement last week that Ottawa will 
not help fund anything less than secondary sewage treatment leaves little 
doubt that Bazan Bay-type system is the bare minimum for Greater Victoria.
It's what Bazan Bay doesn't do that concerns Salter. The plant doesn't 
sterilize it's water discharge, a process used in a growing number of cities 
to kill residual bacteria such as fecal coliform. Sterilization typically 
involves chlorine-based chemicals, ozone or ultraviolet light.
Once that happens, the water is fit for agricultural use.
Water reclamation may not be an issue in rainy Victoria, but in desert-bound 
San Diego it's a necessity. One of the city's sewage treatment plants 
produces 180 million gallons of perfectly good irrigation water a year, 
enough to keep all the city's park healthy and green.
"Our city imports 90 per cent of its drinking water from hundreds of miles 
away, so we recycle the water here," said Eric Wildberger, an engineer with 
San Diego's public works department.
Tertiary treatment takes the process one step further, removing dissolved 
phosphates and nitrogen from the wastewater. Nitrogen can be removed by 
using specialized bacteria that dine on the nutrients and release nitrogen 
gas.
Phosphorous is most commonly removed by using bacteria that ingest high 
concentrations of the substance. The resulting sludge makes excellent 
fertilizer.
In fresh water, nutrient-rich discharges can stimulate weed growth, cause 
harmful algae blooms and generally wreak havoc with the eco-system.
"When you're discharging into salt water like they do at Bazan Bay, that's 
not so much of an issue," Salter said.
However, Greater Victoria could look at cutting edge ways of removing 100 
per cent of heavy metals and contaminants from residual sewage sludge.
One of those is a process called "pyrolysis," a closed system that 
essentially slow-cooks the sludge, releasing methane gas that can be burned 
to generate heat or electricity.
The contaminants are left behind in a concentrated form and can then be 
disposed of without using large amounts of landfill space.
Using a similar process, the Annacis Island sewage treatment plant on the 
Lower Mainland produces enough energy to create the heat required to process 
the sludge.
"It's very close to (energy) self sufficiency," said plant manager Brian 
Hystad.
NEXT WEEK: How other municipalities have addressed their sewage treatment 
needs, using traditional methods, cutting edge technology or, more often, a 
combination of the two.

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