1. Introduction

The district of AMBILOBE is among the 5 districts that make up the Region of DIANA, it is located of 125Km to the South of Diego Suarez. The population of AMBILOBE has about 350 000 women and men and 70% who drink and use the Mahavavy River totally. This for my research is done totally on this River, is that the water used is meets the requirements for drinking required for international standards? So this study is divided into four parts: The 1st bibliographic synthesis, the 2nd measurement results, the 3rd interpretation and discussion of these results, the 4th treatment for microbiological and we will conclude with the conclusion.

2. Bibliographic Synthesis

The general formula of water is H₂O, there are three possible structures: liquid, solid and gaseous. The dissociation in H + and in OH- represents the chemical operation of the water, the Potential of Hydrogen makes it possible to measure the separation of the two ions. The water contains several organic materials presented in dissolved forms. Water constitutes dissolved oxygen-based gases that represent the chemical composition of water. Cations can exist in water such as: Sodium, potassium, magnesium in various concentrations. Metals also like: Total iron; Lead, Copper represent in trace forms. Pollution these very dangerous in water, existence in water present a microbe. Quality standard Reference is made to the recommendation of the European Union (U E), the World Health Organization (O M S) and the Malagasy State (E M).

Norm of quality

1 - Recommendation of the WHO

2 - Recommendation of EU

3 - Recommendation of the EM

Table 1. Recommendation of the WHO

Table 2. Recommendation of the EU

Table 3. Recommendation of the EM

3. Parameters of Analysis

Dosages of iron to know the concentration of iron in the water is in the form of trace, their existence in water is very important for the calcium and magnesium content for the life of the man. Cations such as: Aluminum, Lead, Copper are lord metals their existences in drinking water is not accepted to international standards. Chlorides is a major ion contained in natural water, their presence is very important in drinking water. The concentrations of Calcium and Magnesium in drinking water are very high on all three international standards. Ammonium, Nitrate and Nitrite, their existences in water represent pollution. Title Alkalimetry (T A), Title Alkalimetry Complete (T A C), Carbonates and Bicarbonates: to know the concentration of OH- ion in water, it is the basic salt content. Organic materials such as BOD and COD can be used to estimate the amount of organic matter in the water. To know the quantity of salt dissolved in water, conductivity can be measured. To know that the water is acidic or basic one can measure the pH. To know the transparency of water, one measure the turbidity is that the water is clear.

4. Results of Measures

I- Physical parameters

1- Temperature

Table 4. Represents the measurement of the temperature

Figure 1. Temperature measurement

The value of the temperature found is 19.6°C, is eligible for the three standards required for drinking water [4].

2 – Turbidity

Table 5. Represents the measurement of the Turbidity

Figure 2. Turbidity measurement

The measurement result for turbidity is 3.26 NTU therefore lower than 5NTU it is acceptable for drinking water [1, 2].

3 – pH

Table 6. Represents the measurement of the pH

Figure 3. pH measurement

The pH value found is 7.21 therefore between 6.5 and 9 on average for standards of potability, water is good [4, 5].

4 – Conductivity

Table 7. Represents the measurement of the conductivity

Figure 4. Conductivity measurement

The conductivity measurement result is 53.8 μs/cm, between 180 - 1000 μs/cm, and is therefore acceptable for drinking water.

II- CHEMICAL PARAMETERS

1 – Mineralization

Table 8. Measurement results of Mineralization concentration

Figure 5. Mineralization measurement

There is a relationship between mineralization and conductivity: if the conductivity is lower than 100 μs/cm as already found here 53,8 μs/cm, the mineralization is very low; and for the mineralization to be large it is necessary that the conductivity between 666 - 1000 μs/cm [3].

2 - Total hardness

Table 9. Represents the measurement of the Total hardness

Figure 6. Total hardness measurement

The value of the total hardness found is less than 50°, so the water is not known, but the low hardness can cause corrosion problems [7].

3 - Alkalimetric Title (T A)

Table 10. Represents the measurement of the Title Alcalimetric

Figure 7. Alkalimetric title measurement

The TA value does not exist in this sample [6].

4 - Full Alkalimetric Title (T A C)

Table 11. Represents the measurement of the Full Alkalimetric Title

Figure 8. Full Alkalimetric title measurement

The TA is equal to zero and TAC = HCO^-3, so the quality of the water is on average [6].

5 – Calcium

Table 12. Represents the measurement of the calcium

Figure 9. Calcium measurement

The calcium concentration is 10 mg/L, very low 100 mg/L, so this sample is low in calcium content [10, 15].

6 – Magnesium

Table 13. Represents the measurement of the magnésium

Figure 10. Magnesium measurement

The concentration of magnesium is 9.48 mg/L, lower than 30 mg/L, the magnesium content is low [10, 15].

7 – Bicarbonates

Table 14. Measurement results of Bicarbonates concentration

Figure 11. Bicarbonates measurement

The surface water does not contain more than 10 mg/L of Bicarbonate, but in this sample the concentration found is 29.28 mg/L, so the water is not good.

8 - Organic matter

Table 15. Measurement results of Organic matter concentration

Figure 12. Organic matter measurement

The concentration of organic matter is 1.34 mg/L, therefore less than 2 mg/L for the values required by international standards [3].

9 – Ammonium

Table 16. Measurement results of Ammonium concentration

Figure 13. Ammonium measurement

The concentration of ammonium is 0.16 mg/L, lower than the values required for drinking water standards. [9]

10 - Total Iron

Table 17. Measurement results of Total Iron concentration

Figure 14. Total Iron measurement

The concentration of total iron is normal compared to the concentrations required for drinking water [14].

11 – Chlorides

Table 18. Measurement results of Chlorides concentration

Figure 15. Chlorides measurement

The concentration of chloride is very low compared to the values required for drinking water [12].

12 – Sulphates

Table 19. Measurement results of Sulphates concentration

Figure 16. Sulphates measurement

Sulphate concentration is also very low compared to international standards for drinking water.

13 – Nitrites

Table 20. Measurement results of Nitrites concentration

Figure 17. Nitrites measurement

The nitrite concentration is acceptable for all three drinking water standards.

14 -Nitrates

Table 21. Measurement results of Nitrates concentration

Figure 18. Nitrates measurement

The nitrate concentration is very low compared to the three international standards [16].

15 – Sodium

Table 22. Measurement results of Sodium concentration

Figure 19. Sodium measurement

The sodium concentration is very low compared to the three standards required for drinking water.

III- MICROBIOLOGICAL ANALYSIS

Table 23. Measurement results of the microbiological

Figure 20. Microbiological measurement

The elements sought do not meet the criteria for drinking water.

5. Results Interpretation

- Physical parameters:

The temperature is 19.6°C, the turbidity is 3.26 NTU, the pH is 7.21 and the conductivity is 53.8 μs/cm, the values found are below the values required by the standards of drinking water, so the Mahavavy River water at the physical parameters are good.

Chemical parameters

- Organic matter is equal to 1.34 mg/L, is normal compared to the three standards required, if BOD5 < 3 mg/L is taken as this sample 1.34 mg/L, the water quality is very good.

- The total hardness and calcium hardness are: 6, 9 and 2, 4 °f makes it possible to speak that the water of the sample that we are going to study is not hard.

- The alkalimetric titre and the complete alkalimetric titre are: 0 and 2.4 °f these values show that the carbonate content in the water is low.

- The concentration of Calcium and Magnesium are: 10 mg/L and 9.48 mg/L are admissible for the values required by the standards of potability, despite their deficiencies of the concentration found.

- The chloride and sulphate are: 4.26 mg/L and 4.58 mg/L the concentrations found are less than 250 mg/L required for drinking water.

- Ammonium is equal 0.16 mg/L, less than 0.5 mg/L the required value, so the water is not polluted.

- The carbonate and the bicarbonate are 0 and 29, 28 mg/L, the water of the sample that we will study are lack of carbonate.

- The concentration of sodium is 2.76 mg/L; it is very low by international standards.

Microbiological analysis

The river water of the mahavavy is microbial, it is necessary to treat that before use, so I propose a method of disinfection by Chlorine.

Treatment of water by chlorination

Chlorine is the most widely used reagent for disinfection of water. It is endowed with a very important remanent oxidizing power, favorable to the destruction of the organic matter.

Table 24. Measurement results are available immediately after disinfection

Figure 21. Measurement results are available immediately after disinfection

A minimum contact time of 30 minutes after which the residual chlorine dose must still be 0.1 mg/L at 0, 2mg/L.

This water is taken to make an analysis because only the bacteriological examinations ensure a perfect control of the disinfection. Measurement results are available immediately after disinfection [13].

The values found are perfectly suitable for drinking water.

6. Conclusions

The physical parameters perfectly meet the requirements for drinking water.

The chemical parameters correspond to 90% of the conditions required for the water to be potable, damage some deficiencies of the concentrations found in calcium, magnesium and sodium.

Bacteriological, mahavavy river water is microbial; it must be disinfected before being used. So the proposal is already given the disinfection of water by a Chlorination method.