412
Alcalde et al.
1 Introduction
1.1 General
The growing demand for waters and increasing environmental awareness
stimulates intensive efforts towards improving the treatment and reuse of effluent.
Adequate wastewater treatment and reuse is of ultimate importance primarily in
arid regions. Optimal effluent reuse depends to a large extent on the content of
pathogens (bacteria, viruses and parasites) in the effluent and the related impact on
the soil, plants that human or animal consume. The potential transmission of
infectious diseases by pathogenic agents is the most common concern associated
with non-potable reuse of treated municipal wastewater. (Shuval et ai., 1986;
Crook, 1998). The content of nutrients and the other constituents in the effluent
might have adverse effects on agricultural productivity, both on a short and a longrange time scale. Long range effects are primarily related to dissolved solids
accumulation in the soil, plants and the ground water.
Consequently, research has to focus simultaneously on several areas related to
increase the availability of waters in isolated regions. That includes advanced
irrigation technologies along with improved treatment of domestic, industrial and
agricultural wastes, obtaining effluent quality with minimal health and
environmental risks (Oron et ai., 1990; Oron et ai., 1995). Waste Stabilization
Ponds (WSP) is one of the most appropriate extensive wastewater treatment
methods to reduce pathogens. However, there is still a risk of contamination of
crops and soil irrigated with this kind of effluent.
The purpose of this work was to examine the fate of microbial indicators of
fecal pollution (fecal coliforms, phages F+ and somatic coliphages) in a combined
system ofWSP and Waste Stabilization Reservoirs (WSR).
1.2 Waste Stabilization Ponds
Waste stabilization ponds (WSP) are widespread employed all over the world,
particularly in developing countries located in tropical climates where sufficient
land is normally available and the temperature is more favorable for their
operation. The treatment exploits the physical and biochemical interactions that
occur naturally in aquatic systems involving both algae and bacteria (Mara, 1976).
The operation and maintenance is simple and manageable with low skilled
personnel. Because of this, the cost ofWSP systems is generally low compared to
other wastewater treatment processes. In addition, WSP are not very sensitive to
organic shock loads (Mayo, 1989).
One of the main properties of WSP is their high efficiency in removing
pathogenic microorganisms, whereas in contrast all other treatment processes are
very inefficient at this and require a tertiary treatment process to achieve the same
results (Feachem et aI., 1983).
Alcalde et al.
1 Introduction
1.1 General
The growing demand for waters and increasing environmental awareness
stimulates intensive efforts towards improving the treatment and reuse of effluent.
Adequate wastewater treatment and reuse is of ultimate importance primarily in
arid regions. Optimal effluent reuse depends to a large extent on the content of
pathogens (bacteria, viruses and parasites) in the effluent and the related impact on
the soil, plants that human or animal consume. The potential transmission of
infectious diseases by pathogenic agents is the most common concern associated
with non-potable reuse of treated municipal wastewater. (Shuval et ai., 1986;
Crook, 1998). The content of nutrients and the other constituents in the effluent
might have adverse effects on agricultural productivity, both on a short and a longrange time scale. Long range effects are primarily related to dissolved solids
accumulation in the soil, plants and the ground water.
Consequently, research has to focus simultaneously on several areas related to
increase the availability of waters in isolated regions. That includes advanced
irrigation technologies along with improved treatment of domestic, industrial and
agricultural wastes, obtaining effluent quality with minimal health and
environmental risks (Oron et ai., 1990; Oron et ai., 1995). Waste Stabilization
Ponds (WSP) is one of the most appropriate extensive wastewater treatment
methods to reduce pathogens. However, there is still a risk of contamination of
crops and soil irrigated with this kind of effluent.
The purpose of this work was to examine the fate of microbial indicators of
fecal pollution (fecal coliforms, phages F+ and somatic coliphages) in a combined
system ofWSP and Waste Stabilization Reservoirs (WSR).
1.2 Waste Stabilization Ponds
Waste stabilization ponds (WSP) are widespread employed all over the world,
particularly in developing countries located in tropical climates where sufficient
land is normally available and the temperature is more favorable for their
operation. The treatment exploits the physical and biochemical interactions that
occur naturally in aquatic systems involving both algae and bacteria (Mara, 1976).
The operation and maintenance is simple and manageable with low skilled
personnel. Because of this, the cost ofWSP systems is generally low compared to
other wastewater treatment processes. In addition, WSP are not very sensitive to
organic shock loads (Mayo, 1989).
One of the main properties of WSP is their high efficiency in removing
pathogenic microorganisms, whereas in contrast all other treatment processes are
very inefficient at this and require a tertiary treatment process to achieve the same
results (Feachem et aI., 1983).