الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Providing good and safe drinking-water is world-wide considered to be a fundamental political issue for public health protection, and the primary objective of drinking water treatment and distribution is to deliver to the consumer’s water that satisfy the requirements and does not constitute human health risk.
World health organization (WHO) 2004 defines safe drinking water as does not represent any significant risk to health over a lifetime of consumption, including different sensitivities that may occur between life stages
For centuries, the process of providing safe drinking-water has relied on the application of the ‘multiple barrier concept. Effective treatment barriers are essential in all treatment plants for the effective regulation of both physico-chemical and microbial integrity of water distributed to consumers. Traditionally, the barriers have included protection of water source (water used for drinking-water should originate from the highest quality source possible), coagulation, flocculation and sedimentation, filtration, disinfection and protection of the distribution system.
HACCP (Hazard Analysis and Critical Control Points) can be defined as a preventive system that helps to assure that all products reaching the consumer are safe for consumption. It can lead to the detection, the description, the prediction and the control of hazards in the drinking water.
Hazard is defined as a physical, chemical and a biological agent or a set of conditions that has a potential to cause harm in a certain period of time.
HACCP is a basic concept that underlies the water safety plans. The HACCP system can control the microbiological, chemical and physical hazards to obtain a safe drinking water. Now and due to increase of pollution of Nile River the only surface water source in Egypt drinking water authority must be think to apply HACCP system to increase water quality and control hazards these can be affect on consumers health.
The study was conducted in El-Nozha water purification plant of the Alexandria Water Company. El-Nozha water purification plant receives raw water via pipe from Al-Manshia plant which feed from private canal derived from Mahmoudia Canal before entering Alexandria urban area
The aim of the study is to assess Hazard analysis and critical control points (HACCP) in drinking water purification process and to determine hazards (Physical, chemical, and biological) in Intake, clarifiered, filtered, post-chlorinated, and reservoir water in El-Nozha water purification plant and to identify of critical control points.
The study was carried out from June 2009 to May 2010. Water samples were collected twice monthly for one year to secure 120 samples from the following sites at El-Nozha Water purification plant. Intake, decanted, filtered, post-chlorination and distribution system.
Each sample was analyzed for physical, chemical and biological to determine its criteria and specially the hazards in each step of treatment.
The results revealed that:
• Generally the drinking water produced from El-Nozha water purification plant was comply with Egyptian, WHO, and EPA guidelines in all parameters except blue green algae count which recorded (1424 U/L)
By application of HACCP system it reveled that all purification steps are CCP
1-Raw water
Raw water hazards were microbiological (TC, FC, and F.st) and chemical (Al&Mn) where these parameters not comply with international guidelines as follow,
• Total coliform count ranged between 540-30,000 CFU/100ml which not agree with WHO and European guidelines (5000 CFU/100ml) for drinking water sources also Faecal coliform ranged between 140-12,000 CFU/100ml these results not compatible with European guidelines (2,000 CFU/100ml) and Streptococcus Faecalis ranged between 20-1,300 CFU/100ml these results not compatible with European guidelines (1,000 CFU/100ml).
• Aluminum Al concentration in El-Nozha water purification plant ranged between (0.14-0.19 mg/l) which not agree with Canadian guidelines and Manganese ranged between 0.015- 0.198 mg/l with mean 0.087 mg/l that not agree with Canadian guidelines.
So this step is considered as a CCP.
2-Prechlorination
By Study results of raw water after prechlorination examined and compared it with recommended residual chlorine it noticed that the hazards were residual chlorine and as a result THMs formed during this step. The residual chlorine not compatible with UNICEF guidelines (0.1-0.5 ppm) while residual chlorine value at this step ranged between 0.2-2.4 ppm.
So this step is considered as a CCP.
3-Coagulation, flocculation, and sedimentation
A well operating clarifier should be able to produce an effluent of turbidity equal 2 NTU or less according to WHO guidelines while El-Nozha water purification plant clarifier outlet annual mean turbidity was 3.28 NTU which higher than recommended value. So turbidity is a hazard at this step of purification.
Published data indicate that this process remove between 40-99% of bacteria while the present study showed that clarification process removed between 23 - 87% of bacteria. So bacterial count is a hazard.
Studies concluded that removal of algae by conventional clarifier is 90-95 % while this study showed that algae removed only with 34-77%. So algae is a hazard in this process.
Accordingly coagulation, flocculation and sedimentation (Clarification process) is identified as a critical control point
4-Filtration
Turbidity results of water samples from filter outlet examined and compare it with recommended guidelines it was noticed that turbidity values mean was 0.51 NTU which not compatible with WHO(<0.1 NTU)guidelines and New Zealand standards(<0.3 NTU)
Percent reduction of THPC by filter was 66 % that mean log bacterial removal never reaches 1 log removal as recommended by WHO.
Algae reduction sometimes reaches to 1 log and sometimes not did. This gives indication about fluctuation in efficiency due to slow response to variables in the environmental condition changes.
Filter outlet Zooplankton count during autumn and winter months increased after filtration process while during spring it only reduced by 5.6 %.
So the hazards at this process were turbidity, THPC, algae and zooplankton Accordingly Filtration is identified as a CCP.
5-Post-chlorination (Reservoir water samples)
Residual chlorine after post chlorination not obey USEPA guidelines that caused a serious problem because viruses may be not affected by chlorine dose also Giardia and cryptosporidium. Turbidity of water increased after inter the reservoir although it disinfected by chlorine. Although the turbidity value still within limits of Egyptian, WHO, and EPA guidelines but this is an indicator of low hygiene of the reservoir.
Low % of total bacteria removal after post chlorination which ranged between (37-52 %).
By study results and compare it with disinfected water guidelines it was noticed that hazards appeared was blue green algae.
So the identified hazards at this step were:
• Residual chlorine and as a result THMs formation, total bacteria, and blue green algae.
• The storage of treated water is a CCP due to the risk of recontamination and regrowth.
Accordingly this step is considered a CCP beside storage of water also is a CCP due to afraid from the pollution and re-growth problem of storage water.
6-Distribution system
By comparing results of samples from distribution system with Egyptian drinking water guidelines, WHO. And EPA it revealed that the distribution system water was compatible in all examined parameters but not compatible toward blue green algae according to WHO and EPA specifications.
Finally it can say that El-Nozha Water purification Plant does not need to introduce new treatment methods but rather a number of procedural and operational improvements could be implemented. The purification steps all are CCPs and the created HACCP plan could be used as a supplementary system by the company for improvement.
The study show that the blue green algae is a serious problem in the final treated water, So the study recommended importance of controlling blue green algae growth by optimization of coagulant dose.
So the study recommended that:
• HACCP system must be applying in drinking water purification process to improve water quality.
• Generally Having a Water Safety Plan is positive for the reputation in which it improves understanding of risks and risk management.