Hydrologie : recherche actuelle

In Tamil Nadu state, India, it is the responsibility of the state government to provide drinking water to every household. This is carried out through the lowest elected government at the village level. Of late, the government puts into practice concepts like Demand Driven Approach, which demands the community contribute financially for any social infrastructure to be created, including drinking water supply. This approach seems to give financial matters the overriding priority blinding all the other realities such as actual requirement as per technical standards, and responsibilities of Operation and Maintenance etc. That means being able to contribute financially puts the local community in a position to get water supply infrastructure even excessive of the technical norms. This results in excessive draft of ground water resulting in wastage of fresh water. Especially in a piped water supply system, the water pumped from the ground whether they are used or wasted has an economic value – as this is a service provided using electric power. It is found through an empirical study that the community is insensitive to the cost of water wasted. This study conducted in 17 villages found that all the 17 Village Panchayats (village administrative units) put together, on an average 35 per cent of the water pumped is either excessively used or wasted. It means merely by being judicious in the use of water, each Panchayat has the potential of saving approximately one-third of the expenses incurred on water service delivery. The research paper elaborates this point.

One of the simplest forms of biological treatment processes used in the tropics is the waste stabilization pond (WSP). The relative simplicity and low operating cost of the WSP make it the preferred technology for handling, treatment and disposal of municipal waste for small communities. However, its use in urban areas is limited because of its large area requirement. Hence, the research is aimed at investigating if the introduction of hydraulic jump in the Waste Stabilization Pond can increase treatment efficiency and consequently reduce the land area requirement. Thus, WSPs with varying number of hydraulic jumps were constructed using metallic tanks. The hydraulic jumps were created to introduce turbulence thereby adding dissolved oxygen in the pond. Wastewater samples collected from different points (including inlets and outlets) in the ponds were examined for physio-chemical and biological characteristics for a period of ten weeks. The parameters examined were dissolved oxygen, coliform, biochemical oxygen demand (BOD5), chemical oxygen demand and tracer studies. The efficiencies of the WSPs with respect to these parameters fluctuated with variations in the atmospheric conditions and varying discharge with the highest efficiency obtained from the pond with two hydraulic jumps. The research revealed that the cost of wastewater treatment using hydraulic jump enabled WSP was approximately one and a half times lower than the conventional WSP for the same efficiencies.

The electrolytic treatment of a real industrial effluent and simulated wastewater containing the 1,2-dihydro- 2,2,4-trimethylquinoleyn compound (Naugard Q®) had been investigated in order to improve the wastewater biodegradability. The electrolysis was carried out in a batch electrolytic cell using 70TiO2/30RuO2 electrodes (DSA® anode). After electrochemical treatment, wastewaters were evaluated in terms of Naugard Q® concentration, UV-visible spectrophotometry and biodegradation. Further analyses were conducted in simulated wastewater by gas chromatography and the biodegradation process was monitored using respirometric flasks. Both real effluent and simulated wastewater presented a decrease in Naugard Q® concentration. The simulated wastewater electrolytic treatment provided concentration reduction of Naugard Q® about 52.04% after 60 min, whereas real effluent concentration was reduced by 62.60% after 40 minutes. Furthermore, UV-visible spectra and gas chromatograms presented significant alterations in molecular structure of the compound. After 30 min electrolysis, an increase in simulated wastewater biodegradation was observed. In real effluent, the biodegradation response was faster, as more CO2 was produced in assays that underwent 10 and 25 minutes of electrolytic treatment. This result is probably related to modifications in Naugard Q® molecular structure. It was concluded that the electrolytic treatment followed by bioremediation could be an alternate treatment to degrade this compound.