space
About UNEP
space
space
United Nations Environment Programme
Division of Technology, Industry and Economics
top image
space
space space space
space
space
Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

9.1 Wastewater Characteristics (Topic a)

Domestic sewage is a significant contributor to marine pollution in the Wider Caribbean Region (WCR), the area shown in figure 9.1 below which includes subregions III and IV containing the majority of countries defined as the Caribbean in this Regional Overview (CEP 1998). The Domestic sewage originates mostly from households, public facilities, and businesses. For wastes from communities where most homes and businesses have piped water, typical pollutant composition of domestic sewage is shown in table 9.1.

Table 9.1: Typical pollutant composition of domestic sewage for WCR

Pollutant Measurement (mg/L)
Total Suspended Solids (TSS) 200-300
5-day Biochemical Oxidation Demand (BOD) 200-250
Chemical Oxidation Demand (COD) 350-450
Total Nitrogen as N 25-60
Total Phosphorus as P 5-10
Oil and Grease 80-120
Source: CEP Report No. 40 1998, p8.

In unsewered areas, septic tanks are common (CEP 1998). Septic tanks accumulate solids known as septage, which must be removed every few years to ensure effective operation of the system. Typical pollutant composition of septage taken to wastewater treatment facilities is shown in table 9.2.

Table 9.2: Typical pollutant composition of septage taken to wastewater treatment facilities

Pollutant Measurement (mg/L)
TSS 10,000-25,000
5-day BOD 3,000-5,000
COD 25,000-40,000
Total Nitrogen as N 200-700
Total Phosphorus as P 100-300
Oil and Grease 2500-7500
Source: CEP Report No. 40 1998, p8.

Industrial wastewater has a wide range of pollutant concentrations. According to CEP Report No.40 "Eil refinery wastewater produces 70 percent of the entire BOD load in the Caribbean. These wastes are high in BOD, dissolved salts, odour, phenol, and sulphur compounds. Food processing industries, distilleries, and soft drink industries produce about 5 percent of the BOD load in the Caribbean. They are characterised by very high BOD concentration, suspended solids, dissolved solids, variable pH, and a high level of organic matter. Chemical industries produce about 1 percent of the entire BOD load in the WCR. Even though they have low BOD strength, wastewater from chemical industries is important because it is frequently toxic to aquatic organisms at very low concentrations. This toxicity may actually mask assessment of BOD for these wastes by killing the BOD test organisms. Pesticides and insecticides used for agriculture are the primary chemical wastes in the Caribbean. These wastes are high in organic matter and are toxic to bacteria and fish" (CEP 1998).

Table 9.3 shows typical pollutant characteristics from common industries in the WCR.

Table 9.3: Typical industrial wastewater pollutant characteristics

Industry
 
 
 
BOD
Concentration
(mg/L)
 
TSS
Concentration
(mg/L)
 
Oil & Grease
Concentration
(mg/L)
 
Metals
Present
 
 
Volatile
Compounds
Present
 
Refractory
Organics
Concentration
(mg/L)
Oil Refinery
 
100 to 300
 
100 to 250
 
200 to 3,000
 
Arsenic,
Iron
Sulphides
 
Phenols
0 to 270
Tanneries
 
 
1000-3000
 
 
4000-6000
 
 
50-850
 
 
Chromium
300-1,000
 
Sulphides
Ammonia
100-200
 
Bottling Plant 200 to 6,000 0 to 3,500        
Distillery, Molasses, or Sugar Factory 600 to 32,000
 
200 to 30,000
 
    Ammonia
5 to 400
 
 
Food Processing 100 to 7,000
 
30 to 7,000
 
       
Paper Factory 250 to 15,000 500 to 100,000   Selenium, Zinc   Phenols
0 to 800
Chemical Plant
 
500 to 20,000
 
1,000 to 170,000
 
0 to 2,000
 
 
Arsenic, Barium, Cadmium   Phenols
0 to 5,000
 
Source: CEP Report No. 40 1998, p9.

Table 9.4 presents a regional summary of pollutant loads for the Wider Caribbean Region. As shown in figure 9.1, the subregions III and IV referred to in table 9.4 represent the Caribbean Region in this Regional Overview. It can be seen from table 9.4 that industrial sources account for as much as 80 percent of the pollution load to the Wider Caribbean Basin (CEP 1998). Even though domestic sources are a relatively small part of the total current pollution load, control of pollution from domestic sources is worthy of considerable attention. This is because pollution control from domestic sources is an important element of public education about environmental and public health issues, and because human health risk arises primarily from domestic sewage.

Table 9.4: Summary Of Pollutant Loadings In The Wider Caribbean Basin In Tonnes Per Year

Parameter Subregion I Subregion II Subregion III Subregion IV Subregion V TOTAL
BOD
Domestic
Industrial
115,656
2,245,762
16,785
126,858
71,079
357,441
4,790
94,707
260,171
603,370
506,482
3,428,138
TSS
Domestic
Industrial
116,327
27,821,848
16,427
149,887
90,214
993,964
4,617
270,270
228,744
2,684,948
456,329
31,920,953
TN
Domestic
Industrial
34,070
17,234
2,419
40,526
5,239
43,265
710
37,306
86,338
211,107
128,786
349,435
TP
Domestic Industrial
19,141
17,717
1,467
4,519
5,503
12,690
531
15,171
33,475
32,537
60,117
82,634
Oil & Grease
Domestic
Industrial
41,370
640,181
2,001
8,611
6,089
128,024
504
41,227
18,975
162,608
68,939
908,701
Source: CEP Report No. 40 1998, p9.

Figure 9.1: Sub-Regions in the Wider Caribbean Region

 

      Main Menu

          

  • Brochure
  • IETC Brochure


  • International Year of Forests
  • International Year of Forests


  • World Environment Day
  • ??????


  • UNEP Campaign
  • UNite to Combat Climate Change