1. INTRODUCTION
Water is an essential element for the survival of
all life. Unfortunately, while Pakistan
is blessed with adequate surface and groundwater resources, rapid population
growth, urbanization and unsustainable water consumption practices have placed
immense stress on the quality as well as the quantity of water resources in the
country. Deterioration in water quality and contamination of lakes, rivers and
groundwater aquifers has resulted in increased waterborne diseases and other
health impacts.
In Pakistan,
water remains a critical resource for sustained well-being of its citizens.
The water shortages and increasing competition for
multiple uses of water has adversely affected the quality of water,
consequently, water pollution has become a serious problem in Pakistan. It is
now established that most of the reported health problems are directly or
indirectly related to polluted water. Water is one resource that cannot be
generated it can only be preserved. Farsighted nations try to conserve each
every drop of water available to them because they are aware of the fact that
if this commodity is not prudently preserved and used, the human survival
itself would be jeopardized and future wars would be fought for its possession
and control. The only manner to conserve this resource known to man so far is
to construct dams.
1.1 BACKGROUND
Water resources of the Pakistan are diminishing and there
is very little scope of future water resources development. Unlike most of the
developing countries, Pakistan
consumes up to 98% of its fresh water resources for agriculture, however in
future, the non-agricultural water requirements will increase its share
depending mainly upon the population, leaving less water for agriculture.
Presently, the water use efficiencies in irrigated agricultural areas are among
the lowest in the world, which creates a lot of potential for water savings
provided the utilization of available resources is made with wise management.
The basis for such management is the proper estimation of the future
availabilities from different resources and their requirements by different
competitors. Fresh water is globally a scarce commodity. The optimum
utilization of water resources is utmost importance because the world as a
whole is suffering from vast water shortages. Pakistan is presently faced with
the situation that all its developed water resources are inadequate to meet the
irrigation and other water requirements, and there are no prospects of
augmenting the water availability in the near future (PWP, 2001).
Continuous population
growth with limited land and water resources has put enormous pressure on the
economy of Pakistan.
The water resources of Pakistan
are 172.7 BCM, and are characterized by a great variation. Per capita water
availability in Pakistan
has decreased from 5,000 cubic meters per annum in 1951 to 1,100. The principal
source of drinking water for the majority of people in Pakistan is
groundwater. About 80% of the Punjab has fresh
groundwater, but in Sindh, less than 30% of groundwater is fresh. In NWFP, increasing
abstraction has resulted in wells nowreaching into saline layers, and much of Baluchistan has saline groundwater.
As
per Government figures;
ü
The
Punjab has the best rural water supply amongst
the provinces. It is stated that only 7 % of the rural population depends on a
dug well or a river, canal or stream.
ü
In
Sindh, some 24% of the rural population depends on these sources.
ü
The
rural water supply situation in NWFP and Baluchistan
is worse; about 46% and 72% respectively of the rural population depend on water
from a dug well or from a river/canal/stream.
There
is clear evidence that groundwater in the country is being over-exploited, yet
tens of thousands of additional wells are being put into service every year.
There is an urgent need to develop policies and approaches for bringing water
withdrawal into balance with recharge.
A
national water quality study was carried out by the Pakistan Council for
Research in Water Resources (PCRWR) in 2001. In the first phase of the program,
covering 21 cities, all samples from four cities and half the samples from
seventeen cities indicated bacteriological contamination.
According to the Pakistan Strategic
Country Environmental Assessment Report 2006(SCEA 2006), per capita water
availability in Pakistan
has decreased from 5,000 in1951 to 1100 cubic meter per annum. The increasing
gap between water supply and demand has led to severe water shortage in almost
all sectors.As per Ministry of Environment, Draft
State of the Environment Report 2005
(SOE 2005), Pakistan
stated a population growth rate of 1.9% in 2004. The projected figures for 2010
and 2025 have reached 173 million and 221 million respectively.These estimates
suggest that the country will slip below the limit of 1000 cubic meters of
water per capita per year from 2010 onwards. The situation could get worse in
areas situated outside the Indus basin where
the annual average is already below 1000m3 per head (SOE 2005).Pakistan is
already one of the most water-stressed countries in the world, a situationwhich
is going to degrade into outright water scarcity (WB).
Here
the existing status of water quality is being presented:
2. CURRENT
SITUATION / ISSUES OF WATER IN PAKISTAN
2.1. WATER
AVAILABILITY The
stress on water resources of the country is from multiple sources. Rapid urbanization,increased
industrial activity and dependence of the agricultural sector on chemicals and
fertilizers have led to water pollution. Deterioration in water quality and
contamination of lakes, rivers and groundwater aquifers has, therefore,
resulted in increased water borne diseases and negative impacts on human
health.
Water availability on a per capita basis
has been declining at an alarming rate. It has been decreased from about 5,000
cubic meters per capita in 1951 to about 1,100 cubic meters currently, which is
just above the internationally recognized scarcity rate.
It
is projected that water availability will be less than 700 cubic meters per
capita by 2025 (Pak-SCEA 2006).The principal source of drinking water for the
majority in Pakistan
is groundwater.
Most
of the rural areas and many major cities rely on it, although some cities such
asIslamabad, Karachi, Hyderabad etc., get water from a number of other sources.About
80% of Punjab has fresh groundwater, with some saline water in the south and in
desert areas. There is also some evidence of high fluoride or arsenic content locally
in Punjab. A number of locations have also been
contaminated by industrial wastewater discharges. In Sindh, less than 30% of
groundwater is fresh. Much of theprovince is underlain by highly brackish water
and some instances of elevated fluoride levels. In NWFP, increasing abstraction
has resulted in wells now reaching into saline layers, and much of Balochistan
also has saline groundwater (Pak-SCEA2006).
As per government figures, Punjab has the best rural water supply amongst the provinces.
The vast majority of the rural population has either piped water or water from
a hand pump or motor pump. It is stated that only 7 % of the rural population depends
on a dug well or a river, canal or stream. The situation in Sindh is considerably
worse: some 24% of the rural population depend on these sources. The situation
in rural Sindh also appears to have deteriorated. The rural water supply situation
in NWFP is worse still, and is worst of all in Balochistan. In these
twoprovinces, 46% and 72% of the rural population, respectively, depend on
water from a dug well or from a river/canal/stream (SOE 2005).
Over 60% of the population gets their
drinking water from hand or motor pumps, with the figure in rural areas being
over 70%. This figure is lower in Sindh, where thegroundwater quality is
generally saline and anestimated 24% of the rural population getswater from
surface water or dug wells. Inalmost all urban centres, groundwaterquantity and
quality has deteriorated to theextent that the availability of good quality
rawwater has become a serious issue. Overabstraction has also resulted in
declininggroundwater levels (Pak-SCEA 2006).
Uncontrolled
extraction of groundwater and extended dry periods has also caused itsdepletion
and drying up of some of the sources. A study in Kirther shows that thewater
table has dropped by 3 meters per year on average. The drying up of wells has important
social consequences, particularly on the women and children responsiblefor
water collection. In Islamabad, the drop has
been 50 feet between 1986 and 2001while in Lahore the drop has been about 20 feet
between 1993 and 2001. Estimatesshow that without an artificial recharging,
groundwater in the sub basin
of Quettawould be
exhausted by 2016. (SOE 2005)
It is important to note that although,
there is a clear evidence that groundwater isbeing over-exploited, yet tens of
thousands of additional wells are being put intoservice every year. Pakistan has
now entered an era in which laissez-faire becomesan enemy rather than a friend.
There is an urgent need to develop policies
andapproaches for bringing water withdrawals into balance with recharge.
Sincemuch groundwater recharge in the Indus Basin
is from canals, this requires anintegrated approach to surface and groundwater.
There is little evidence thatgovernment and/or donors have re-engineered their
capacity and funding to deal withthis great challenge. The delay is fatal in
this situation, because the longer it takes todevelop such actions, the greater
would become the depth of the groundwater table, and the higher would be the
costs of the “equilibrium” solution. (WB, CWRAS 2005)
|
Per Capita Water Availability
|
|
Year Population (million)
|
Per Capita Availability (m3)
|
|
1951
|
34
5300
|
|
1961
|
46
3950
|
|
1971
|
65
2700
|
|
1981
|
84
2100
|
|
1991
|
115
1600
|
|
2000
|
148
1200
|
|
2013
|
207
850
|
|
2025
|
267
659
|
Source:
Draft State of Environment Report 2005
The
water shortage in the agriculture sector is another serious issue. As per
SOE2005, the shortage has been estimated at 29% for the year 2010 and 33% for
2025.
In
addition, uncontrolled harvesting of groundwater for irrigation purposes has
alsoled to severe environmental problems. Today groundwater contributes a mere
48%of the water available. The construction of private wells for irrigation has
also beenpromoted through a policy of high subsidy on electricity cost. The
hike in the cost ofelectricity in 1990s, and the development of new
technologies have led to aconsiderable increase of diesel pumps whose numbers
have grown 6 times over thelast 30 years. (SOE 2005)
3. WATER
DEMAND/CONSUMPTION
According
to the National Water Policy (NWP), at present, irrigation uses about 93%of the
water currently utilized in Pakistan.
The rest is used for supplies to urban andrural populations and industry.
However, as mentioned earlier, Pakistan's
populationis set to increase by 221 million by the year 2025, the percentage of
water required, particularly for urban water supply, is set to increase
dramatically. This will placefurther pressure on water resources which are
already deficient in meeting demandsacross all sectors (NWP).
|
Pakistan’s Water Scenario
|
|
Year
|
2004
|
2025
|
|
Availability
|
104 MAF
|
104 MAF
|
|
Requirement(including drinking water)
|
115 MAF
|
135 MAF
|
|
Overall Shortfall
|
11 MAF
|
31 MAF
|
Source:
Ten Year Perspective Development Plan 2001-11, Planning Commission
It
is observed that the expanding imbalance between supply and demand has notonly
led to water shortages but also initiated an unhealthy competition amongst
endusers, which is ultimately causing environmental degradation in the form of
persistentincrease in water logging in certain areas, decline of groundwater
levels in otherareas, intrusion of saline water into fresh groundwater
reservoirs, etc. (NWP).
4. WATER QUALITY
Domestic
waste containing household effluent and human waste is either
dischargeddirectly to a sewer system, a natural drain or water body, a nearby
field or an internalseptic tank. It is estimated that only some 8% of urban
wastewater is treated inmunicipal treatment plants. The treated wastewater
generally flows into open drains, and there are no provisions for reuse of the
treated wastewater for agriculture orother municipal uses.
Table below shows ten large urban centres of
the country, which produce more than 60% of the total urban wastewater
including household,industrial and commercial wastewater. (WB-CWRAS Paper 3,
2005)
|
City
|
Urban
Population (1998 Census)
|
Total
Wastewater Produced (million m3/y)
|
% of
Total
|
% Treated
|
Receiving
Water Body
|
|
Lahore
|
5,143,495
|
287
|
12.5
|
0.01
|
River
Ravi, irrigation canals,
vegetable
farms
|
|
Faisalabad
|
2,008,861
|
129
|
5.6
|
25.6
|
River
Ravi, RiverChenab and vegetable farms
|
|
Gujranwala
|
1,132,509
|
71
|
3.1
|
-
|
SCARP
drains, vegetable farms
|
|
Rawalpinidi
|
1,409,768
|
40
|
1.8
|
-
|
River
Soan and vegetable farms
|
|
Sheikhupura
|
870,110
|
15
|
0.7
|
-
|
SCARP drains
|
|
Multan
|
1,197,384
|
66
|
2.9
|
-
|
River Chenab,
irrigation canals and vegetable farms
|
|
Sialkot
|
713,552
|
19
|
0.8
|
-
|
River Ravi,
irrigation canals and vegetable farms
|
|
Karachi
|
9,339,023
|
604
|
26.3
|
15.9
|
Arabian
Sea
|
|
Hyderabad
|
1,166,894
|
51
|
2.2
|
34.0
|
River Indus,
irrigation canals and SCARP drains
|
|
Peshawar
|
982,816
|
52
|
2.3
|
36.2
|
Kabul River
|
|
Other
|
19,475,588
|
967
|
41.8
|
0.7
|
-
|
|
Total Urban
|
43,440,000
|
2,301
|
100.0
|
7.7
|
-
|
Source: Master
Plan for Urban Wastewater (Municipal
and Industrial) Treatment Facilities in
Pakistan. Final Report, Lahore: Engineering, Planning and Management
Consultants, 2002
Another
important aspect is that there is verylittle separation of municipal wastewater
fromindustrial effluent in Pakistan.
Both flow directly into open drains, which then flow intonearby natural water
bodies. There is noregular monitoring programme to assess thewater quality of
the surface and groundwaterbodies. There is no surface water qualitystandard in
Pakistan.
A comparison of thequality of surface water with the effluentdischarge standard
clearly demonstrates theextent of pollution in the water bodies due tothe
discharge of industrial and municipal effluent. (WB-CWRAS Paper 3, 2005).There
is also no regular monitoring of drinking water quality. A national water
qualitystudy was carried out by the Pakistan Council for Research in Water
Resources (PCRWR) in 2001. In the first phase of the programme, covering 21 cities,
all samples from four cities, and half the samples from seventeen cities
indicatedbacteriological contamination. In addition, arsenic above the WHO
limit of 10 ppbwas found in some samples collected from eight cities. The same
study alsoindicated how the uncontrolled discharge of industrial effluent has
affected surfaceand groundwater, identifying the presence of lead, chromium and
cyanide ingroundwater samples from industrial areas of Karachi, and finding the
same metals in the Malir and Lyari rivers flowing through Karachi and
discharging into the ArabianSea. A second PCRWR study was launched in 2004, and
preliminary results indicateno appreciable improvement, while a separate study
reported that in Sindh almost95% of shallow groundwater supplies are
bacteriologically contaminated (Pak-SECA2006).
Water samples collected from Karachi harbour have also
revealed the presence oftrace metals in concentrations far exceeding any other
major harbour in the World.
About
5.6 million tons of fertilizer and 70 thousand tons of pesticides (GoP, 2003)
are consumed in the country every year. Pesticide use is increasing annuallyat
a rate of about 6%. Pesticides, mostly insecticides, sprayed on the crops mix
withthe irrigation water, which leaches through the soil and enters groundwater
aquifers.In 107 samples of groundwater collected from various locations in the
countrybetween 1988 and 2000, 31 samples were found to have contamination of
pesticidesbeyond FAO/WHO safety limits. A pilot project was undertaken in 1990-91
inSamundari, Faisalabad District, over an area of 1,000 km2, to look into the
extent ofgroundwater contamination by agrochemicals. In an analysis of ten
groundwatersamples drawn from a depth of 10-15 m, seven were contaminated with
one or morepesticides (PCRWR, 1991). The study concluded that the contamination
had reachedonly the shallow aquifers; however, there were evidences that it was
graduallyreaching the deeper aquifers as well. As there has been a four-fold
increase in theuse of pesticide use in the country since 1990, the
contamination levels are likely tohave increased significantly (WB-CWRAS Paper
3, 2005).
In addition to municipal and industrial
effluents, contamination of groundwater byarsenic is also becoming a serious
problem. In Sindh and the Punjab,
approximately 36% of the population is exposed to a level of contamination
higher than 10ppb and 16% is exposed to contamination of 50ppb. (SOE 2005)Due
to impact of water shortage and accompanying pollution, many wild animals, plants,
aquatic species, birds and other forms of flora and fauna are also affected.The
biodiversity in Sindh is particularly at risk as biotic potential of many
species is starting to be diminished, and they may be lost forever if the
environmental devastation due to water shortage is not reversed or properly
controlled.(SOE 2006)
5. MAJOR WATER
SECTORS IN PAKISTAN
5.1. INDUSTRIAL
SECTOR
The
pressures on water resources due to industrial growth are quite significant and
have increased water pollution problems. According to the SOE 2005, only a marginal
number of industries conduct environmental assessments (about 5 % of national
industries). The national quality standards specifying permissible limits of wastewater
are seldom adhered to. In Pakistan,
only 1% of wastewater is treated by industries before being discharged directly
into rivers and drains. For example in NWFP, 80,000 m3 of industrial effluents
containing a very high level of pollutants are discharged every day into the
river Kabul causing observable incidence of skin diseases, decrease in
agricultural productivity and decrease in fish population (SOE 2005).
Major
industrial contributors to water pollution in Pakistan are petrochemicals, paper and
pulp, food processing, tanneries, refineries, textile and sugar industries. The
industrial sub-sectors of paper and board, sugar, textile, cement, polyester
yarn, and fertilizer produce more than 80% of the total industrial effluents
(WB-CWRAS Paper 3, 2005)
The
problem of industrial water pollution remained uncontrolled because there have been
little or no incentives for Industry to treat their effluents. Although, rules
and regulations exist but lack of implementation and absence of proper
monitoring and policing has resulted in problem persisting (WB-CWRAS Paper 8,
2005). Throughout Pakistan,
the industrial approach towards environment is the same; In Lahore, only 3 out
of some 100 industries using hazardous chemicals treat their wastewater.
Biological Oxygen Demand (BOD) levels in water courses receiving these wastes are
as high as 800mg/l and Mercury levels over 5 mg/l. Consequently hundreds of
tons of fish are killed causing a loss of millions of rupees. (WB-CWRASPaper 8,
2005)
5.2. AGRICULTURE
SECTOR
According
to the information provided in the National Water Policy (NWP), the irrigation network
of Pakistan
is the largest infrastructural enterprise accounting for approximately $ 300
billion of investment (at current rates) and contributing nearly 25% to the
country's GDP. Irrigated agriculture provides 90 % of food and fibre requirements
while "barani" (rain fed) area contributes the remaining 10 %
(NWP).At present, irrigation uses about 93% of the water currently utilized in
Pakistan. The rest is used for supplies to urban and rural populations and
industry (NWP).
In addition to the study of PCRWR on
groundwater contamination due to pesticides and fertilizers mentioned earlier
under section 2.3, another study by WAPDA on the situation of pollutants in the
drainage system of Pakistan
was conducted in April 2004. The study revealed that in Punjab
all drains were carrying saline and sodic waters due to high values of Total
Dissolved Solids (TDS) and Residual Sodium Carbonate (RSC) or Sodium Absorption
Ratio (SAR) and all of them also had very high values for Chemical Oxygen
Demand (COD) and Biological Oxygen Demand(BOD). The data for Sindh and
Balochistan showed that majority of drains had very high saline waters due to
high values of TDS and in Shahdad Kot drain this reached as high as 13,187ppm
during 2002. In addition, the COD values were higher than the permissible
limits and at some sampling points these even surpassed the high levels recorded
for Punjab and NWFP (SOE 2005).The contribution of agricultural drainage to the
overall contamination of the water resources exists but is marginal compared to
the industrial and domestic pollution.For example, in Sindh, the pollution of
water due to irrigation is only 3.21% of the total pollution (SOE 2005).
5.3. MUNICIPAL
SECTOR
Most
surface water pollution is associated with urban centres. Typically, nullahs
and storm water drains collect and carry untreated sewage which then flows into
streams, rivers and irrigation canals, resulting in widespread bacteriological
and other contamination. It has been estimated that around 2,000 million
gallons of sewage is being discharged to surface water bodies every day
(Pak-SCEA 2006).Although there are some sewerage collection systems, typically
discharging to the nearest water body, collection levels are estimated to be no
greater than 50% nationally (less than 20% in many rural areas), with only
about 10% of collected sewage effectively treated. Although treatment facilities
exist in about a dozen major cities, in some cases these have been built without
the completion of associated sewerage networks, and the plants are often either
under loaded or abandoned. In effect, only a few percent of the total wastewater
generated receives adequate treatment before discharge to the waterways.
(Pak-SCEA 2006)
6. WATER
SCARCITY & DESERTIFICATION
As
desertification takes its toll, water crises are expected tocontinue raising
ethnic and political tensions in drylands, contributing to conflicts where
water resources straddle ordelineate country borders. In some countries,
landdegradation has led to massive internal migrations, forcingwhole villages
to flee their farms for already-overcrowdedcities. 50 million people are at
risk of displacement in thenext 10 years if desertification is not checked (UNU
2007).
Implementing
sustainable land and water managementpolicies would help to overcome the
challenge of theseincreasingly extreme situations.
Water scarcity
leaves a lasting impact on soil: Desertification is land degradation in dry
lands, resultingfrom various factors including climatic variations and humanactivities.
Water scarcity is the long-term imbalancebetween available water resources and
demands.
Increasing
occurrences of water scarcity, whether natural orhuman-induced, serve to
trigger and exacerbate the effectsof desertification through direct long-term
impacts on landand soil quality, soil structure, organic matter content
andultimately on soil moisture levels. The direct physical effectsof land
degradation include the drying up of freshwaterresources, an increased
frequency of drought and sand anddust storms, and a greater occurrence of
flooding due toinadequate drainage or poor irrigation practices. Should
thistrend continue, it would bring about a sharp decline in soilnutrients,
accelerating the loss of vegetation cover. This leadsin turn to further land
and water degradation, such aspollution of surface and groundwater, siltation,
salinization, and alkalization of soils.
Poor
and unsustainable land management techniques also worsen the situation. Over
cultivation, overgrazing anddeforestation put great strain on water resources
byreducing fertile topsoil and vegetation cover, and lead togreater dependence
on irrigated cropping. Observedeffects include reduced flow in rivers that feed
large lakessuch as the Aral Sea and Lake Chad, leading to thealarmingly fast
retreat of the shorelines of these naturalreservoirs in Central Asia and Northern Africa.
(Fig: Breaking the downward spiral of Desertification through Sustainable Land and Water Resources Management; SLWRM)
The
Virtuous Circle
for SLWRM improvement starts from
Land
condition improvement
7. REMEDIAL
MEASURES FOR WATER SCARCITY
According to UNCCD (2009), desertification, land
degradation and drought have negative impact on the availability, quantity and
quality of water resources that result in water scarcity. The challenges and
threats of water scarcity to dry land populations are set to increase in
magnitude and scope. As the world’s population has swollen to well over 6
billion people, some countries have already reached the limits of their water
resources. With the existing climate change scenario, almost half the world’s
population will be living in areas of high water stress by 2030, including
between 75 million and 250 million people in Africa.
In addition, water scarcity in some arid and semi-arid places will displace
between 24 million and 700 million people (UNCCD, 2009).
8.
WATER REMEDIATION AND WASTEWATER TREATMENT SYSTEMS
According to Boari,
et al. (1997), continental natural waters are the classical source for
supplies of drinking water. Spring water is the best drinking water because of
the natural conditions which guarantee hygiene standards and generally preclude
any specific treatment. Also groundwater usually has good chemo-physical
characteristics, because bacteria and viruses are eliminated by filtration with
the movement of the water as are other polluting substances. It is impossible
to specify a precise method for treating surface waters because of the various
qualities of waters that exist. Nevertheless, a series of conventional
processes can be identified; such as screening, straining, oxidation,
clari-flocculation filtration. These can be followed by specific stages for the
removal of particular pollutants (Boari,
et al., 1997). The typical composition of natural water is given in
table, but this composition varies in different areas of the world (Berbenni, P. 1991).
Table
1: Typical composition of natural waters (Berbenni, 1991)
8.1. Natural Water Treatment Systems
One of the most common and efficient methods for
removing micro-pollutants is the process of absorption on activated carbon.
This is often combined with an ozonization process. Stripping processes are
used to remove volatile micro-pollutants such as solvents, chloride, ammonia
and sulphide. Natural lakes can be an excellent source of drinking water
supplies if the chemical, physical and biological treatment systems naturally
formed in the water mass keep the water clean (Masotti, 1996). This depends on the hydraulic and
geomorphologic characteristics of the catchment-basin (nature of the soil, the
conveyance of solids etc.); on the type of vegetation and fauna composing the
ecosystem of basin and its surroundings; and finally a point not to be
overlooked - on the anthropogenic activity which degrades the basin. The
treatment used for water of good quality is generally that illustrated in Fig
1a.
Fig
1a: Systems for treatment of lake and reservoir waters (Masotti, 1996).
Waters collected in natural lakes or artificial
reservoirs where eutrophic processes take place are characterized by low
quality. Under these conditions organic material is suspended in high
concentrations, and the growth of certain species of algae which thrive in
particular conditions, obstructs the process of rendering the water potable (Masotti, 1996). The sediment at the
bottom provides condition in which iron and manganese are readily made soluble.
If intervention to clean the waters of the lake does not have lasting effect a
more complex treatment system must be designed, such as that described in Fig
1b.
Fig
1b: Systems for treatment of lake and reservoir waters (Masotti, 1996).
8.2. Urban Wastewater Treatment Systems
Systems commonly used for treatment of urban
wastewater are constituted of primary treatment by settling, a biological
second stage, and a tertiary treatment by disinfection, in some cases following
a filtration process. Primary sedimentation is most efficient in removing
coarse solids.
Biological processes are used to convert the finely
dissolved organic materials in wastewater into flocculent settle able solids
that can be removed in sedimentation tanks.
These
processes are employed in conjunction with physical and chemical processes and
they are most efficient in removing organic substances that are either soluble
or in the colloidal size range. Disinfection is generally operated by
chlorination with Cl, or NaOC1 (Metcalf
and Eddy, 1998). The main systems for removal of solids, organic matter
and pathogens are the activated sludge process, trickling filters, aerated
lagoons, high-rate oxidation ponds, stabilization ponds (fig 2a) or aerated
lagoons (fig 2b) are most often used for small installations (Masotti, 1996).
Fig
2: Flow-sheet f or stabilization pond (a) and aerated lagoon (b) processes (Masotti, 1996).
8.2.1
Activated Sludge Process, or one of its many
modifications, is most often used for larger installations. In some cases
trickling filters are applied. Several processes have been used for activated
sludge. The most important are (Metcalf
and Eddy, 1998): tapered aeration process; modified aeration process;
continuous-flow stirred tank; step aeration process; contact stabilization
process; extended aeration process; oxidation ditch; carrousel system;
high-rate aeration process etc.
Fig
3 - Typical
simplified flowsheets for biological processes used for urban wastewater
treatment: (a) activated sludge, (b)trickling filter (Masotti, 1996).
8.2.2.
Contact-Stabilization process was developed to take advantage of the absorptive properties of activated
sludge. It has been postulated that BOD removal occurs in two stages. The first
is the absorptive phase, which requires 20 to 40 min; during this phase most of
the colloidal, finely suspended, and dissolved organics are absorbed in the
activated sludge. The second phase, oxidation, then occurs, and the absorbed
organics assimilated metabolically (Metcalf
and Eddy, 1998).
In the contact-stabilization process, the two phases
are separated and occur in different tanks. The settled wastewater is mixed
with return sludge and aerated in a contact tank for 30 to 90 minutes. The
sludge is then separated from the treated effluent by sedimentation, and the
returned sludge is aerated for 3 to 6 h in a sludge aeration tank. The
flowsheet is shown in Fig 4 The aeration volume requirements are approximately
50 percent of those of a conventional or tapered-aeration plant. It is thus
often possible to double the plant capacity of an existing conventional plant (Metcalf and Eddy, 1998).
Fig.
4 - Flowsheet
for contact stabilization activated sludge process (Metcalf and Eddy,
1998).
8.2.3. Extended-Aeration process operates in the endogenous respiration phase of the growth curve,
which necessitates a relatively low organic loading and long aeration time.
Thus it is generally applicable only to small treatment plants with capacities
of less than 3800 m3/d. This process is used extensively for prefabricated
package plants that are provided for the treatment of wastes from housing
subdivisions, isolated institutions, small community and schools. Although
separate sludge wasting generally is not provided, it may be added where the
discharge of the excess solids is objectionable.
Aerobic
digestion of the excess solids, followed by dewatering on open sand beds,
usually follows separate sludge wasting. Primary sedimentation is omitted to
simplify the sludge treatment and disposal. The oxidation ditch is essentially
extended aeration process. It is used in many small European towns and has
found a variety of different applications in the United States. A schematic
representation of an oxidation ditch with intermittent operations is shown in
Fig 5 (Canziani, 1990). It
consists of a ring-shaped channel about t1o 1.5 m deep. An aeration rotor, consisting of a modified Kessener brush, is
placed across the ditch to provide aeration and recirculation. The screened
wastewater enters the ditch, is aerated by the rotor. The cycle consists of closing the inlet valve and aerating the
wastewater, stopping the rotor and letting the content settle, and operating
both inlet and outlet valves thereby, allowing the incoming wastewater to
displace an equal volume of clarified effluent. Modifications can be made for
continuous operation.
Fig 5: Oxidation ditch
activated sludge process with intermittent operation (Canziani, 1990).
9. RECLAIMING WATER FROM MUNICIPAL EFFLUENTS
9.1. Direct Utilization of Municipal Wastewater:
The most suitable use of municipal wastewater
treatment plants effluents is agricultural irrigation. The accomplishment of
this produces numerous advantages but requires a severe analysis of the effects
on the people, soils and crops, and definition of the proper treatment process
to get required quality level. The main advantages of utilizing effluents for
irrigation uses consist in the fact that many of the substances present in
wastewater can be used as nutrients for crops, and would otherwise probably
contaminate the water body receiver, and there is the additional advantage that
less chemical fertilizers are needed (Lopez and Liberti, 1992).
The salinity
level of wastewater and the organic and inorganic toxic compound content are
usually not high enough to prevent its use for irrigation purposes.
Nevertheless, it is advisable to check on the presence of these substances. Wastewater
must be refined so that the concentration of suspended matter is brought down
to a suitable level and its pathogenic load eliminated. Simpler and less costly
alternative systems have been tested, which eliminate clari-flocculation, but
include the coagulation and flocculation and sedimentation (Lopez and Liberti,
1992).
The
disinfection processes and the removal of suspended solids are especially
important as many pathogenic agents are closely attached to solid particles or
to colloidal agglomerates in suspension. It is essential that suspended solids
are efficiently removed in order to ensure that the wastewater has been
satisfactorily disinfected. The removal of phosphorus, when required, implies
additional operating costs as the precipitation and disposal of chemical sludge
is necessary (Lopez and Liberti, 1992).
The
clari-flocculation stage, achieved through the processes of coagulation,
flocculation and sedimentation, permits the removal of solids, principally of
the organic nature, which are present in the secondary effluent. Filtration,
following sedimentation or an alternative method, is an indispensable stage as
it renders the wastewater limpid and therefore perfectly suitable for
disinfection. Moreover, this is an essential condition for the destruction of
viruses and parasites, which are extremely resistant to disinfectants.
Filtration is most commonly achieved by using homogeneous, single-layered sand
filters or the dual-media type filters, containing a mixture of sand and
anthracite, which also permit the removal of soluble organic compounds, at
moderate, rather than high, operating costs (Lopez and Libert, 1992).
The advantage
to industry of using urban wastewater should be determined in the light of a
number of certain aspects such as:the distance between the industry and the
source to wastewater supply; any cleaning treatment at the expense of the
industry; the absence of alternative water supplies; prospects of increasing
productivity in the future without the possibility of having access to further
supplies (Lopez and Libert, 1992).
9.2.
Groundwater Reclamation from Municipal Wastewater is obtained by recharging of ground water. This process prevents
depletion taking place by recovering water resource which otherwise would be
lost. The recharging of ground water with refined wastewater could become a
reality in many arid zones. Nevertheless, the viability of its application must
be analyzed in the context of each locality, which may be quite different from
the localities, where refining and recharging plants have already been
installed; and moreover the possibility of growth from the reuse of refined
sewage should be analyzed (Treweek,
1999).
Recharging
methods can be applied to both superficial and deep waters; natural water can
be used as well as purified wastewater provided that all the necessary
precautions have been taken and thorough checks carried out. If purified
wastewater is used, the processes should focus mainly on the removal of
suspended solids, the destruction of toxic solutes and on the microbiological
load.Fig 6shows the refining process for purified civil waste and the
recharging of groundwater in the Dan region, which involves addition by
infiltration in sandy ground which is partially muddy with layers of clay (Treweek, 1999). In Fig 7, the Cedar
Creek (United States)
plant where infiltration is operated in ground consisting of a mixture of sand
and gravel with clay deposits in the first layer, and diffusion is used to
reach deeper layers of extremely low permeability.
Fig 6: Lay-out of
refining process for civil waste and recharge of groundwater at theDan plan tin
Israel
(Treweek, 1999).
Fig 7: Lay-out of Cedar
Creek plant for recharge of groundwater by infiltration and aspersion of
treated urban wastewater (Treweek, 1999).
Globally, water scarcity already affects four out of
every 10 people. The situation is getting worse due to population growth,
urbanization and increased domestic and industrial water use. Most countries in
the Near East and North Africa suffer from acute water scarcity, as do
countries such as Mexico, Pakistan, South Africa, and large parts of China and
India (CWC,1988; NCIWRDP, 1999; Garg and Hassan, 2007). Now a major
international issue, climate change is expected to account for global increase
in water scarcity. Countries that already suffer from water shortages will be
hit hardest. Significantly, there will be major increases in water scarcity
even if the water impacts of climate change prove to be neutral or even
enhancing of the world’s hydrological budget (IPCC 2001, 2007).
10.
SUGGESTED REMEDIAL MEASURES
- There is an impressive array of specific management measures, both
structural and non-structural, that water managers already use routinely
to accommodate present day climate variability. These will also serve
towards adaptation to any impacts of enhanced climate variability and
climate change.
- Basin-wise assessment of per-capita water requirement using
integrated approach, in which water quality and population growth must be
accounted for.
- Recycling and re-use of waste water in a big way.
- Water harvesting and water conservation from agricultural and rural
areas as national policy.
- Inter-basin water transfer after proper feasibility analysis of all
the basins and surrounding areas including groundwater potential.
- Proper urban planning to reduce concentrated development, which
increases pollution, water demand etc., which is difficult to cope up.
- Public awareness program on impact of climate change in water
resources, coping mechanism and adaptation strategies for the
stakeholders, public etc (Ramakar, K., Sharma, D. and Neupane, B., 2008).
11. CONCLUSIONS, POSSIBLE SOLUTIONS AND THE WAY
FORWARD
The issues of water
quality and quantity in Pakistan
discussed are considered grave in nature. A number of factors need to be
highlighted and addressed in order to improve, protect and maintain the quality
of freshwater resources of the country. These factors include;
- Government Priorities: The treatment of sewage and industrial
effluents seems to be a low priority with the Government and there is a
need to bring provision of clean water back as a top priority.
- Rules and Regulations: Unregulated groundwater abstraction is the
main cause of water depletion. Unfortunately there are no clear
guidelines, rules and regulations for groundwater abstraction. In
additions, surprisingly, there are no surface water classification
standards in the country so such rules and regulations have to be
established at the earliest, for stopping groundwater abstractions.
- Water Policy: Although relevant policies like
ü
National Environment
Policy,
ü
National Water Policy
(Draft),
ü
National Drinking Water
Policy (Draft) etc.
Are in place, there is no clear strategy
devised so far to implement them. A clear and practical strategy needs to be
defined to implement these policies.
- Better water management practices - reuse, conservation etc. with financial constraints and a water
resource problem across the country, water conservation, re-use, and
industrial water recycling are areas that are considered crucial.Better
management practices should be used in agricultural sector such as
switching from high delta crops to those crops requiring less water inputs
etc.
- There should be an incentive based
public campaign emphasizing the need to conserve water at all levels.
In households, leaking taps, tank overflows, irresponsible use of potable
water for washing cars and watering lawns and plants must account for a
significant proportion of non revenue water. Water metering is a must but
with an intermittent supply of water it is of little use (PCRWR, 2005)
In conclusion, even
though water is one of the most important requirements for life and Pakistan is a
semi-arid country, water use practices in the country fall far short of the
required minimum for water conservation and water quality. In simple terms, Pakistan’s
water is drying up, and what little remains is heavily polluted. We need to
make sure that our practices change if Pakistan is to survive the next few
decades.
___________________________________________
REFERENCES/BIBLOGRAPHY
WATER
SCARCITY
Ø ‘National Water Policy (Draft)’ (2005), Ministry of Environment,
Government of Pakistan
Ø
‘Pakistan
Environmental Protection Act, 1997
Ø ‘Pakistan Water Sector Strategy’ (2002), Ministry of Water and Power, Office of the Chief Engineering Advisor/ Chairman federal Flood Commission, vol.
5
Ø Dixon, T. (1999). Environment, Scarcity and Violence. Princeton: Princeton University Press, p. 48.
Ø <http://www.asiawaterwire.net/node/243>
Ø <http://www.pakistan.gov.pk/ministries/environment-ministry/media/mtdf.htm>
Ø <http://www.usaid.gov/stories/pakistan/fp_pakistan_water.html>
Ø MTDF (2005), Medium Term Development Framework, Planning Commission,
Government of Pakistan
Ø National Environmental Policy (2005), Ministry of Environment, Government
of Pakistan
Ø NIH (2004)Survey by the ‘Network’, National Institute of
Health
Ø PCRWR (2005), ‘Water Quality
Status’ 3rd Report,
Pakistan Council of Research in Water Resources
Ø Shahid, K. (2005), ‘Drinking Water and Sanitation Sector Review of Policies and Performance
and Future Options for Improving Service Delivery Country Water Resources Assistance Strategy’, paper 8
Ø
The World Bank (2005), ‘Pakistan Country Water Resources
Assistance Strategy Water Economy:
Running Dry’.
Ø Wolfe, S. and Brooks, D. (2003). Water scarcity: An alternative view and
its implications for policy and capacity building. Natural Resources Forum 27,
p. 99-107.
Ø
Zakaria, W. (2005), ‘Water and Environmental Sustainability Country Water Resources Assistance Strategy’ paper 3
REMEDIAL
MEASURES
Ø Berbenni P. (1991). ‘Evolution of
Tertiary Treatment Requirements; California’,
Water
Environment Technology, vol.4, No. 2
Ø Boari, G., Mancini, I and Trulli, E. (1997),
Technologies for water and wastewater treatment, Options Mediterranean’s, seriesA, No. 37
Ø Canziani R., (1990), Application of
Reverse Osmosis to Wastewater Treatment, Journal WPCF,vol. 46, pp. 301-311
Ø CWC
(1988), Water resources of India,
Publication No. 30/88, Central Water Commission, New Delhi
Ø Garg,
N.K. and Hassan, Q. (2007), ‘Alarming scarcity of water in India’, Current
Science, Vol. 3, No. 7, pp.
932-941
Ø Intergovernmental
Panel on Climate Change (IPCC) (2001), Third Assessment Report (TAR): Synthesis
Report (Summary for Policymakers) 34 p., The Scientific Basis; Impacts,
Adaptation and Vulnerability (IAV) pp. 1032 <http://www.ipcc.ch>
Ø Intergovernmental
Panel on Climate Change (IPCC) (2007), Fourth Assessment Report <http://www.ipcc.ch>.
Ø Lopez, A. and Liberti, L. (1992), New
Technologies for Municipal Wastewater Treatment. Water Science and Technology, vol. 18,
No. 12, pp. 41-53
Ø Masotti L. (1996), Integrated
Biological Treatment for High Strenght Agro-Industries Wastewaters, In Proceedings of 4th
International Conference on Ecosystem for Wastewater Treatment, Yuancun
(China)
6-10 November.
Ø Metcalf and Eddy, Inc. (1998),
Wastewater
Engineering: Treatment, Disposal, Reuse., McGraw-Hill Publishing Company
Ltd., New Delhi, 2nd edition, 6th reprint.
Ø NCIWRDP
(1999), Integrated water resources development: A plan for action, Report of
the National Commission for Integrated Water Resources Development Plan,
Ministry of Water Resources, New Delhi.
Ø PCRWR
(2005), ‘Water Quality Status’ 3rd
Report by Pakistan
Council of Research in Water Resource
Ø Ramakar,
K., Sharma, D. and Neupane, B. (2008), Traditional
and Innovative Technique for Supporting the Identification and Remediation of
Water Scarcity Issues and Global Change Impact on Water Resources- An Indian
Scenario.
Ø Treweek G.P., (1999). Pre-treatment
processes for groundwater recharge. In Artificial Recharge of
Groundwater, edited by T. Asano, Butterworth Publishers, Boston.
United Nations Convention to Combat
Desertification (2009), ‘Water scarcity and desertification’, A Thematic
factsheet, series 2, <http://www.unccd.int