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8.1 Wastewater characteristics (Topic a)

Unfortunately there is lack of sufficient data available to assess typical characteristics of wastewater produced in the Region. However the following information has been obtained.

8.1.1 Domestic wastewater

The Kinoya wastewater treatment plant in Suva, Fiji, caters for a population of 85,000. Incoming BOD and suspended solids (SS) are approximately 450mg/L and 290mg/L with final effluent at 20-45mg/L and 30-60mg/L respectively. Average dry weather flows are in the order of 270 litres per person per day (l/p/d) while peak wet weather flows are 550 l/p/d. In American Samoa two primary treatment plants treat domestic sewage only, and have a combined average daily discharge of 8160m³ with 2600 house and business connections. Average influent for the two plants (in October 1998) shows that BOD and SS were 70mg/L and 50mg/L respectively. Average effluent quality from the two plants, during the same period, was BOD at 30mg/L and SS at 17mg/L. The sewage has been descried as "weak" due to leaking faucets and running toilets. This is reflected in an estimated average flow of 520 l/p/d, which is similar to the peak wet weather flow of the Kinoya treatment plant in Fiji.

No specific information could be found on other wastewater characteristics such as nitrogen and phosphorus concentrations.However a South Pacific Regional Environment Programme (SPREP) publication Land-Based Pollutants Inventory for the South Pacific Region, (see References) has estimated waste loads from domestic wastewater per year that enters the environment as shown in Table 8.1 below. These were based on each country's estimated population, using various methods of treatment and an estimated concentration for each characteristic (ie BOD, SS, N, and P)

8.1.2 Industrial wastewater

Most operators of Regional wastewater treatment plants indicated that industrial wastes were not allowed into their collection systems. It would be naive to think that illegal connections did not exist. Major industries in the Regions include edible oils, sugar refining, fish canning and beer brewing. Most industrial operations provide some sort of treatment and disposal systems, but again there is little information available plus a lack of discharge monitoring. Potential economic opportunities exist with expanding industry growth along with increased industrial waste types and volumes that will have to be dealt with to protect the environment. More control over discharges will need to be exercised by government authorities to minimise adverse effects to the environment.

Mining activities exist in PNG, New Caledonia, Nauru, Fiji, Solomon Islands and Vanuatu all produce wastewater that requires treatment and are potentially dangerous to the environment. Each mining operation would have its own treatment facilities. The disposal of mining wastewater has not been considered in this report.

The SPREP publication also provides estimated waste loads from industrial wastewater within the Region as shown in Table 8.2.

8.1.3 Stormwater disposal

There does not appear to be any combined wastewater and stormwater collection systems in the Region. Apart from the larger urban centres in the Region, stormwater collection and disposals systems do not exist. Normally stormwater would follow natural or man-made surface water channels to the sea or just left to seep into the surrounding ground. Stormwater that falls on roofs could be used for domestic water supplies in many SIDS or discharged into the surrounding ground. Potential exists to use stormwater to recharge groundwater aquifers or freshwater lenses that are used for water supply purposes. Instead of directing stormwater to the nearest outlet, the rainwater could be infiltrated into the ground by soakage wells or ponds. Photo 8.1 shows a stormwater disposal well use in Guam.

However, it is expected that some stormwater would enter wastewater sewer systems through old and poorly constructed pipes, and through illegal connections. An example of this would be the difference in the dry (270 l/p/d) and wet (550 l/p/d) weather flows for Fiji�s Kinoya treatment plant as noted in section 8.1.1 above.

Photo 8.1: Stormwater disposal well in Guam

8.1.4 Cultural influences

The most drastic influence on wastewater disposal methods would have been that imposed by Western society on the indigenous people by those countries that colonised the Pacific Region. Prior to this intervention I would have imagined that waste disposal was a simple matter managed by families and villages. It was Western society that introduced systems that collected and concentrated large volumes of waste to be discharged at point sources, into the sea or rivers causing pollution of marine and freshwater resources. Many of these systems failed to be sustainable due to lack of resources and local inputs into operation, maintenance and understanding of the systems. (See Case Study 1) Photo 8.2 shows a community toilet in Tarawa, Kiribati that has not been maintained.

Photo 8.2: Community toilet in Tarawa, Kiribati that lacks daily maintenance

8.1.5 Environment and public health

Tables 8.1 and 8.2 indicate the order of pollutants that are discharged into Pacific SIDS environment each year. Approximately 80% of the pollutants enters the coastal marine zone. This very important zone that provides food and recreation for both SIDS residents and tourists is under attack from both land-based and on-the-water pollution. The attributes that attract tourists (sandy beaches, excellent diving and fishing) are being threatened by increasing algal blooms, dying coral and decreasing numbers of marine life. Bathing and eating seafood from polluted coastal waters puts public health at risk as well.

In many atolls freshwater lenses, that have traditionally been used as a source of water, are now being polluted by poor wastewater disposal practices and by increasing population densities of both people and animals. At times people are forced to use polluted water sources thus increasing the risk of poor public health. In many SIDS, local health centres consistently treat a large number of water borne related diseases.

Improved wastewater disposal planning, management and systems would definitely have a positive impact on the environment and improve the general health of SIDS residents.

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