Module 6: Water Supply and Waste Treatment

Issues

• Natural water• Domestic water• Sewage

Occurrence of Freshwater in the Arctic

• Glaciers and ice caps hold much of Arctic’s freshwater (Greenland’s ice cap contains 10% of world’s freshwater)

• Glaciers and accumulated snow in mountain feed Arctic rivers

• Many wetlands, ponds, and lakes

• Groundwater is scarce in permafrost areas

Freshwater Cycle

Key Characteristics of Arctic Freshwater

• Drastic cycles in lakes and rivers each year– Thick or solid ice in winter high water flow in spring (can be

destructive)

• In areas dominated by vegetation, freshwater carries high concentrations of dissolved organic carbon (DOC)– E.g. humic and fulvic acids (colour the water)

• Supports an array of flora and fauna in sediment and water column (bacteria, protists, algae, micro-invertebrates)

• Essential habitat for freshwater fish (few in Arctic), anadromous fish, waterfowl, mammals

• Part of the freshwater food web that recycles carbon, nitrogen, phosphorous, and other nutrients

Overview

• Impacts on aquatic receiving environment• Import of nutrients to marine environment• Import of toxicants to marine environment• Barrier to fish migration

Mackenzie River Delta

Concepts

Acid rain• Rainfall with a pH of less than 7.0 (in

practical terms, <5.0). • Rain + Sulphur Dioxide• Same as acid deposition

Effects are a function of the pH buffering capacity of the environment.

ConceptsNutrients• As a pollutant, any element or compound, such

as phosphorous or nitrogen, that fuels abnormally high organic growth in aquatic systems (i.e. eutrophication).

• As a fertilizer, any element or compound, principally P, N, K, S, that are limited in availability, hence influence plant growth (e.g. algae) in water

Note: Can be used to precipitate pollutants in algae through long-term sedimentation.

Concepts

Effluents• The sewage or industrial liquid waste that

is released into natural water by sewage treatment plants or structures to treat industrial water (including mine water)

Receiving waters• A river, lake, ocean, etc., into which waste

water or treated effluent is discharged

Drinking Water in the North

Issues• Wells for extracting ground water is not an

option• Underground water lines in permafrost

require insulation; installation of such infrastructure is a challenge

• Reservoirs are above ground and insulated

• Quality drinking water is generally available

Sanitation of WaterInadequate sanitation may lead to:• Gastrointestinal illness• Hepatitis A• Bronchitis• Meningitis• Other bacterial infection• Skin and eye diseases

Note: lack of running water has consequences in terms of poor hygiene

Concepts

Drinking Water:

• Water intended for human consumption but which has other household uses

Best Practices

• Prevention of the contamination of water sources (lakes, rivers, streams, and groundwater sources)

• Treatment of water• Proper maintenance of water distribution

systems• Regular monitoring of drinking water• Public education and awareness (especially for

“in house” water distribution)

Waste Water

Sewage• Liquid waste from toilets, baths and showers,

kitchens, that is disposed via sewers, trucking, or on site treatment systems

Industrial Waste Water• Waste water from industries of mines. Generally

involves some on site processing

Treatment Stages

• Primary: Mechanical treatment to reduce coarse solids, sand and dirt, oils and grease

Note: Ideal as pre-treatment or for treating “surface” water (e.g. street water)

Note: Involves screening, sedimentation, skimming

Treatment Stages

• Secondary: Treatments designed to degrade biological content of sewage (e.g. human waste, food waste) through aerobic biological processes

Note: Require aeration for bacterial and protozoan activities to degrade organic compounds

Note: Effluent water and sludge are by-products

Treatment Stages• Tertiary: Advanced stages of treatment to raise

the effluent quality to the standard required before it is discharged to the receiving environment

Potential steps: Filtration, polishing, ponding (lagoons, wetlands), nutrient removal, disinfection.

Note: Industrial contaminants remain an issue.

Primary Sewage Treatment

Common Options for Secondary Sewage Treatment

Treatment Process

Description Key Features

Activated Sludge Process (ASP)

Oxygen is mechanically supplied to bacteria which feed on organic material and provide treatment

Sophisticated process – many mechanical & electrical parts, needs careful control of operator; provides high degree of treatment.

Aerated lagoons

Like lagoons but with mechanical aeration

Not very common; oxygen requirement mostly from aeration and hence more complicated and higher operational and maintenance costs.

Land Treatment (soil –aquifer treatment – SAT)

Sewage is supplied in controlled conditions to the soil

Soil matrix has quite a high capacity for treatment of normal domestic sewage, as long as capacity is not exceeded. Some pollutants, such as P, are not easily removed.

Issues for Arctic Environments

• Small communities cannot support extensive sewage treatments

• Storage tanks and transfer sites (closed to houses) are sources of contamination

• Overland treatment of raw sewage is often the only approach to treat sewage

• Nutrient loading and sewage-based contaminants are key issues

• Leaching into the marine environment

LAGOON 1 LAGOON

2

LAGOON 3

PUMP SYSTEM

OVERLAND FLOW AREA

Arviat, Nunavut

Arviat, Nunavut