UNEP Logo Appropriate Technology for Sewage Pollution Control in the Wider Caribbean Region

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Caribbean Environment Programme Technical Report #43 1998 All CEP Technical Reports

Part 2.
COUNTRY REPORTS

 

Domestic and Industrial Wastewater Treatment Techniques in Barbados

Anthony S. Headley
Deputy Chief Environmental Engineer (ag), Environmental Engineering Division
Ministry of Health and the Environment, Culloden Farm, Culloden Road, St. Michael, Barbados
Tel: 246-436-4820/6, Fax: 246-228-7103, Email: msquared@surf.com


1.0 Introduction

At present, Barbados can be defined as a small island state whose economy is in transition. The country has sustained economic growth for the last four years, life expectancy is increasing for the population while conversely, more chronic diseases are treated in the health care system. In the environmental management field, recent studies are indicating that the ground water resources are showing signs of stress from human activity both in terms of quality and quantity. The marine water quality is deteriorating which corresponds to a reduction in the diversity and abundance of coral reef systems and fisheries resources. Generally, Barbados is experiencing the problems associated with commercial, residential, economic and political development, which mirrors previous development trends displayed by the now developed world.

Since 1992, policy makers have been engaged in constant discussions on sustainable development with a systematic, controlled approach to sustainable development policy implementation. One of the main questions asked at discussions, which is relevant to all concerned stakeholders and Barbadians is, how can we preserve the quality of our environment for our enjoyment and the enjoyment of generations after us ?

Right now, you are probably wondering what does this have to do with domestic and industrial wastewater treatment. However, before one can appreciate the state and urgency of wastewater treatment and the management of treatment systems, one must appreciate the historical, existing and future perspective, the relationships between social and economic trends and the impacts these activities have on environmental quality. My presentation will provide an overview on domestic and industrial wastewater treatment in Barbados, but I will try to connect this to the sustainability development concept being advocated.


2.0 Present Wastewater Treatment Methods

2.1 History of Wastewater Treatment

Barbados is a unique geological marvel of the Caribbean. Eight-five (85%) of the land mass is Pleistocene Coral Limestone underlain by oceanic or impermeable clays. The other fifteen (15%) is composed of mainly clays, shales and sandstone and is situated in an area known as the Scotland District on the north east coastline in the parishes of St. Andrew and St. Joseph. When evaluating disposal options, the geology and hydrogeological characteristic of the soils are key factors in determining the appropriate method(s) for final disposal of wastewater. Nine soil classifications have been identified and are presented in Figure 1.

Like most other countries, pit latrines were utilised for centuries as the appropriate means for the final disposal of human faeces, gray (kitchen and bath) water and storm water. In the late fifties and early sixties, studies done by Senn and Tullstrom made certain recommendations, which are still utilised to this day.

As a result of these studies, a national zoning policy for the protection of the island's ground water reserves and the control of domestic and industrial wastewater was instituted in 1963. Table 1: The Principal Features of the Development Control Zones provides the development restrictions for domestic and industrial wastewater control. Figure 2 provides a pictorial representation of these control zones. As you can see, the entire coastal strip is designated as control zone 5 and ironically, most tourist related developments and activities occur in this zone.

Table 1: The Principal Features of the Development Control Zones

ZONE

DEFINITION OF OUTER BOUNDARY

MAXIMUM DEPTH OF SOAKAWAY PIT

DOMESTIC CONTROLS

INDUSTRIAL CONTROLS

1

 

 

 

 

2

 

 

 

3

 

 

4

 

5

300 day travel time

 

 

 

 

600 day travel time

 

 

 

5-6 year travel time

 

Extended to all high lands

Coastline

None allowed

 

 

 

 


6.5 m

 

 

 


13 m

 

 

No Limit

 

No Limit

No new housing or water connections

No changes to existing wastewater disposal except when water authority secures improvements

 

 

Septic tank of approved design, discharged to soak away pits

Separate soak away pits for toilet effluent and other domestic waste water

New premises or alterations to new existing systems must be certified by the Environmental Engineering Division (Ministry of Health and the Environment)

No storm runoff to sewage soak away pit

No new petrol or fuel oil tanks

As above for domestic wastewater disposal

Petrol or fuel oil tanks of approved leak proof design

No restrictions on domestic wastewater disposal

Petrol or fuel oil tanks of approved leak proof design

No restrictions on domestic waste water disposal

Siting of new fuel storage tanks subject to approval of water authority

No new Industrial development

 

 

 

 


All Liquid Industrial wastes to be dealt with as specified by the Water Authority

 

 

 

 

 


Maximum Soak away pit for domestic waste


2.2 Package Treatment Facilities

The Public Health Engineering Division (now the Environmental Engineering Division) originally approved most private wastewater treatment facilities approximately twenty years ago in the 1970's. These facilities were traditionally installed at tourist related establishments (hotels). Today, twenty tourist related establishments have package wastewater treatment systems, while only one known agricultural and industrial establishment have installed systems to improve the quality of their wastewater prior to sub-surface discharge.

Table 2 also indicates that based on the limited monitoring efforts (quarterly sampling) by the EED, effluent discharges are consistently of a poor to average quality. Few treatment facilities meet their BOD5 design specification, which range between 20 mg/L to 30 mg/L or comply with adopted standards for BOD5 of 25 mg/L by the EED. Of the twenty three (23) operating treatment plants, 8.7 % produce a good quality effluent while 43.5% and 26.1 % discharge effluents of average and poor quality respectively to the environment. The effluent from twenty-one percent (21.7%) of the operating plants is not monitored. These plants will be included in the sampling scheduled for 1999.

There are several reasons why effluent quality does not meet the required design specifications and discharge standards adopted by the Ministry. The main ones include:

1. there is a high probability that operators are not fully trained to operate existing sewage treatment systems;

2. operators are not totally aware of the discharge guidelines and proposed discharge requirements;

3. wastewater treatment is not viewed as a priority by most hoteliers and hence, maintenance of most plants are secondary;
        and

4. the employee turn over rate is suspected to be a contributing factor. Persons originally trained to operate the plant after it
        was installed are no longer employed by the establishment.


2.3 Central Treatment Schemes

Currently, Barbados is constructing a 44 km sewer system capturing wastewater flows (11,300 m3/day) within the 6 m contour on the south coast for treatment at the recently completed Graeme Hall primary treatment plant. The Master Plan for the West Coast Sewerage Treatment Facility was presented to Government in September 1998 for final review and comments prior to submission the Inter-American Development Bank for funding. The Bridgetown Sewerage System has been in operation since 1982 and serves Bridgetown the capital. Sewer lines extending from the Bridgetown Port Authority to Lower Bay Street however, connections to the sewers were not mandatory so some communities in Bridgetown are not connected to the system. This system discharges approximately two million gallons per day of treated wastewater to the marine environment through a long ocean outfall.


2.4 Wastewater Reuse

Wastewater recycling is a practice which is becoming increasingly popular amongst hoteliers. The water is mainly used for irrigation purposes in drip irrigation systems on golf courses and flower garden. No standards have been adopted for wastewater reuse but standards were developed and proposed for the West Coast Sewerage Treatment scheme.


3.0 Environmental Problems

Several problems can result from the lack of, or inadequate treatment of domestic and industrial wastewater. Of main concern is the deterioration in the quality of recreational marine water. Typical repercussions that are observed are: occasional fish kills at various surface water locations on the island, algae blooms, reduction and diversity of coral reef systems and reduction in the safety of the recreational marine water. Plans to perform epidemiological studies to further evaluate the risk factors associated with recreational water are being develop.

When considering the practice of wastewater reuse, what springs to mind is the increase potential for the transmission of water borne diseases and infections. The consequences are health and economic based being closely related to the sustainability of the tourism sector. It should be recognised that wastewater reuse increases the exposure pathways for human contact with infectious agents and micro-organisms. If not managed properly, represents a danger to the tourism sector and the fabric of the Barbadian economy.


4.0 Legislation

One of the legislative instruments C Barbados Water Authority Act C which governs wastewater treatment, treatment facilities and effluent disposal was drafted with the understanding that the enforcement agency would have been the Barbados Water Authority (BWA). However, the Environmental Engineering Division has adopted the regulatory role for private and public wastewater treatment systems.

The Division operates on the basis of limited legislative authority embodied in the Health Service Act, 1969. There are two main legislative tools, the Disposal of Offensive Matter 1969 and the Nuisance Regulation, 1969, which are generally used by the EED to regulate private and public wastewater treatment facilities.

A more focused legislation instrument C the Marine Pollution Control Act C which makes provisions for the establishment of standards and guidelines has been drafted. It is expected that this Act should be ratified by Parliament prior to year’s end.


5.0 Plans for Wastewater Treatment Plants

These include:

1. implementation of the Marine Pollution Bill;
2. formation of an Environmental Standards Review and Assessment Committee (ESRAC);
3. development of environmental guidelines and standards for water pollution control;
4. operator will be required to perform mandatory analyses for key performance indicators and report to the
        Ministry of Health and the Environment on plant' s performance; and
5. operators will require certification from a recognised academic institution accredited by the Ministry of
        Health and the Environment to operate a wastewater plant.

Table 3: Recommended Maximum Values For Treated Sewerage Effluent

Parameter

Maximum Value

BOD - 5

25 mg/ L

SS

30 mg/ L

Faecal Coliform

400/ 100 ml at point of discharge

Residual Chlorine

0.2 mg/ L


Table 4: Proposed Wastewater Reuse Criteria

Parameter

Value

Cane and Pasture Lands
Treatment Criteria (mg/L)
Disinfection Criteria (faecal Coliform/100 ml)
Application rate (mm/yr)
Location

 
Secondary,<20 BOD5,<20 TSS
<2,500
<800
Outside Zone 1

Golf Courses
Treatment Criteria (mg/L)
Disinfection Criteria (faecal Coliform/100 mL)
Application rate (mm/yr)

 
Tertiary < 10 BOD5,<10 TSS + N Removal
<2
<800

High Rate Irrigation
Treatment Criteria (mg/L)
Disinfection Criteria (faecal Coliform/100 mL)
Application rate (mm/yr)

 
Tertiary <10 BOD5,<10 TSS, <5 T N,<5 TP
<2
<2 to 3

Cash Crops

Tertiary <10 BOD5,<10 TSS + N Removal


Table 5: Proposed Wastewater Reuse Criteria

Parameter

Value

Suckwells to non-potable aquifers
Treatment Criteria (mg/L)
Disinfection Criteria (faecal Coliform/100mL)
Application rate (m3 effluent/m2 suckwell)

 
Secondary,<20 BOD5,<20 TSS + N Removal
<2,500
80

Irrigation Basins
Treatment Criteria (mg/L)
Disinfection Criteria (faecal Coliform/100mL)
Application rate (mm/yr)
Suckwell configuration (L:W:D)

 
Secondary,<20 BOD5,<20 TSS
<2,500
20 to 300
2:2:10

West Coast Sewerage Project
Technical Memorandum No. 11 Design Criteria/Parameters
by: Standley International Group Inc.
in association with Klohn-Crippen Consultants Ltd.
and Consulting Engineers Partnership


6.0 Conclusion

Wastewater treatment has an integral role to play in the protection and preservation of environmental resources and the general health of the population. We must all play our part in ensuring the environment is safe for our generation and generations after us. However, this role doesn't stop at the installation of a wastewater treatment system. Owners, operators and responsible government agencies must recognise that this is just the first step in a process of continuous improvement. The development planning cycle for t he installation and operation of a wastewater treatment system must make provisions to include long term operational and maintenance cost and the cost to train and retain plant operators. When these vital elements are neglected for large facilities, they become significant point pollution sources. A poorly maintained and operated treatment plant is as effective as no treatment.


References

Barbados Water Resources Study Vol. I 1978
Bridgetown Sewage Re-use
Standley Associates Engineering Ltd.
Consulting Engineering Partnership Ltd.

Barbados Water Resources Study Vol. II 1978
Introduction, Summary and Master Plan
Standley Associates Engineering Ltd.
Consulting Engineering Partnership Ltd.

Feasibility Studies on Coastal Conservation
Nearshore Benthic Communities of the West and South Coast of Barbados: Importance, Impacts, Present Status and
    Management Recommendations
Delcan 1993

Feasibility Studies on Coastal Conservation
Terrestrial Water Quality Report
Delcan 1995

Providing A Sustainable Water Supply for Barbados
Barbados Water Authority

Groundwater Pollution Risk Assessment for the Belle Public Water Supply Catchment, Barbados
Ministry of Health-Environmental Engineering Division, Bridgetown, Barbados
PAHO/WHO, Office of the Caribbean Program Coordinator (CPC), Bridgetown, Barbados
PAHO/WHO, Pan American Center for Sanitary Engineering and Environmental Sciences (CEPIS), Lima, Peru,
        British Geological Survey, Hydrogeological Group (BGS), Wallingford, Great Britain
June, 1989

Groundwater Pollution Risk Assessment for the Hampton Catchment, Barbados
Ministry of Health-Environmental Engineering Division, Bridgetown, Barbados
British Geological Survey, Hydrogeology Group (BGS), Wallingford, U.K.
Caribbean Environmental Institute (CEHI), Castries, St. Lucia
May 1991

Groundwater Pollution Risk Assessment for the Hampton Catchment, Barbados
Results of Monitoring in the Belle and Hampton catchment, 1987-1991
Ministry of Health-Environmental Engineering Division, Bridgetown, Barbados
British Geological Survey, Hydrogeology Group (BGS), Wallingford, U.K.

West Coast Sewerage Project Master Plan Report
Government of Barbados, Ministry of Public Works, Transport and Housing
Standley International Group Inc.
Klohn-Crippen Consultants Ltd.
Consulting Engineers Partnership Ltd.
May 1998

 

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Foreword   |  Editorial  |  Part 1 | Part 2  | Part 3  | Appendice 1 | Appendice 2   | Appendice 3  | Appendice 4  |  Appendice 5


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