PROCEDURE AND PLANT FOR THE USE OF GROUNDWATER

METHOD AND INSTALLATION FOR MAKING USE OF GROUNDWATER.

The present invention relates to a method for making use of groundwater, sensed by drilling.

The groundwater resource although generally of better quality than the surface water due to the natural treatment of certain pollutants in the subsoil, is also vulnerable to long term. Groundwater allow more than 60% of the production of drinking water in Europe. Increasingly, the quality of the resource is to a great extent by the pollutions diffuse agricultural and communal. New undesirable substances (endocrine disruptors...) are regularly discovered, sign of a human pressure on the resource always stronger. Each year during the summertime, many restrictions are imposed on resource usage. These difficulties highlight the fragility of certain resources. They are also generating economic losses for firms dispensing drinking water.

The company Plugmatic has developed a technique for recharge of the webs that supports the webs level by introducing water pretreated surface. Preprocessing the surface water before injection requires the investments as high water quality resupplying used; it generates further amounts of sludge also costly to treat.

The evolution of quality requirements for potable water in a context of impairment resources, and placing increasingly heavy environmental standards, including the sludge treatment of drinking water, cooperate to increase prices for producing drinking water, this in an economic context increasingly competitive.

The groundwater have many qualitative advantages compared to most surface water but require for their operating land occupation sometimes substantial. Numerous resources located near places of consumption were taken up in urban or industrial development of their environment. It is now important conflicts of interest between the production of potable water and the other actors socioeconomic institutional on which the boreholes are implanted. In addition, the legislation on the groundwater protection, particularly in France, has not always permitted to supply the proper degree of protection of these resources.

Facing such difficulties and in order to secure their water resource, the operators must be able to implement operational measures to protect the resource's complement existing administrative measurements. It is pragmatic approaches to protect their resources that provide an acceptable compromise by the different actors premises. Treatment techniques generally provide water damage response more of the subterranean resource. But they are responsible for processing large amounts of sludge (from impurities in the raw water and reagents) that by treating (dehydration before disposal or reprocessing optional) to limit their impact on the environment.

In addition, the need of curative treatments at the customer's premises generates a dissatisfaction with respect to the price of the water and also a mistrust against of water quality distributed imaged opposite their ideal environmental. Us - b - 4 576,717 proposes a method for making use of groundwater collected by drilling, using at least two levels of successive pumping of the water from the web prior to use. In this method, the system artificial recharge takes place under reducing conditions by percolating water on a mixture of straw and sand. The system requires delivery artificial and renewed the organic reagent consisting of straw.

The aim here, above all, to provide a solution for reducing the production cost of potable water and investment needed. The invention also aims to improve the quality of groundwater resources, standardizing the protection while monitoring the environmental impact and socio-economic activity on the local actors.

In particular, the invention aims to ensure the production of drinking water quality with simplification of treatment required factory and substantial decrease in sludge attributed to processing. According to the invention, the method for making use of groundwater collected by drilling, using at least two levels of successive pumping of the water from the web prior to use, is characterized in that it comprises a primary pumping taking the ground-water in a the sector is fast recharging from the surrounding surface water, and where it benefits from a natural filtration in the basement, and a natural purification by reducing conditions, the water from the first pump being sent into an artificial recharge basin in contact with ambient air but without reducing organic reagent or to create locally oxidizing conditions, where it infiltrates towards the web undergoing a second filtering, and a secondary pumping performed near the recharge basin before use.

Preferably, the primary pumping is performed along a watercourse, river, or along a river, lake or pond, or a wall plate. The primary pumping may be further performed in a river, lake or pond, or a sand quarry intercepting the groundwater in an area where its refill is rapid.

The artificial recharge basin used for filtration in aerated medium oxidizer is generally a wall plate or gravel pit.

The water from the pump may be subjected to a secondary treatment, carried out by a factory, which is limited to refining and disinfecting before distribution of water. The refinements may be implemented on activated carbon. Thus, according to the invention, the artificial recharge system takes place in an oxidizing medium without the addition of organic material and by simple contact with the air.

The invention also relates to a plant for making groundwater collected by drilling, comprising at least two successive pumping stations of the ground-water before use, characterized in that it comprises a pumping station taking the primary ground-water in a sector where the recharging is fast from the surrounding surface water and where it benefits from a natural filtration in the underground and a natural purification by reducing conditions; an artificial recharge basin in contact with ambient air but without reducing organic reagent or to create locally oxidizing conditions, into which is directed the water pumped by the primary pumping station; a secondary pumping station for pumping near the recharge basin; and a plant for a simplified treatment of water.

The processing plant may include only a polishing unit and a disinfecting station. The refining unit can be provided for refining on activated carbon. Other features and advantages of the invention will be given in the examples which follow, with reference to the drawings on which:

Figure 1 is a schematic view in section of an installation for implementing the method of treating water according to the invention. Figure 2 is a similar view to Figure 1 representing an example implementation of the process, and

Figure 3 is a similar view to Figure 2 represents another example implementation of the process.

By referring to Figure 1, we can see a part of an installation for implementing the method according to the invention with two levels of successive pumping water from the ground water prior to directing it to the processing plant (not shown).

This approach relies on knowledge flows underground and biochemical mechanisms that occur in the subsoil 1, of different aquatic environments (gravel pits, rivers, ponds infiltration) and the combination of their ability to purify. It is desired to use the maximum natural filtration aquifers, geologic formations containing either permanent or temporary water mobilizable.

A first pumping called primary pumping 2, takes up the ground-water, from a gravel pit drilling or intercepting the groundwater, in a sector where the recharging is rapid, as for example along a water course 3, river, or ply of fresh water, lake or pond, or an upper sill or gravel pit or the like in connection with a water course.

Infiltrating water benefits from natural filtration in the basement 1. the reducing properties of the medium surrounding the river 3 4 in particular permit the nitrate removal. This removal is accomplished without the use of a carbonaceous substrate artificial but by utilizing and activates the flow of water into a medium 4 rich in organic matter. The oxidizers contained in surface water (which nitrates) are absorbed by the natural organic materials of the soil and subsoil 1.

Water from the primary pumping 2 is sent in at least one artificial recharge basin 5, outdoors, generally with a spillway promoting the oxygenation of the water. The ponds are maintained without a plant (which accumulate organic matter) are largely free of storages of organic material. From these basins, water seeps the web undergoing a second filtering, this oxidizing aerated medium 6. the oxidative properties of the medium 6 in particular permit the removal ammonium, the precipitation of iron and manganese surface, without however that there is clogging of the aquifer in depth.

A second pump 7, called secondary pump unit and located near ponds resupplying, supplies the processing plant. The method of the present invention surprising a gait of pumping water from one ply and not used immediately for consumption, but to reinjection into the ground for a new pump usage tracking.

Could, if necessary, repeat the cycle and re-injecting the second pumping water into the ground for one or more infiltration cycles and pumping, to improve the quality of the water supplied to the plant. The succession to oxidizing environments and reductants 4 6 can be complemented for example using media that has both oxidizing and reducing areas, such as for example a gravel pit whose water column is oxidizing and reducing sediment. Then takes in the succession of media a complete removal of inorganic nitrogen (ammonium nitrate) and reduced compounds by a sequence nitrifying, denitrifying, oxidation.

The configuration of the invention enables to pass through at least two different natural media, one of which has reducing properties and the other oxidative properties. These types of media are easily identifiable and controllable in the environment (shores of rivers, ponds, pits, infiltration basins). Volatile organic compounds, as well as the majority of metals are removed in the natural environment.

Most of the new annoying that complicate the processing chains and generate sludge are avoided.

The processing plant performs a number of operations since the method of the invention can remove, at the factory, number of complementary treatments such as settling, filtering, nitrifying, metallic iron, [...], which have occurred naturally. All digests or surface water treatments are avoided as many investments, reagents and byproducts avoided. In particular, the decrease in the amount of sludge produced has a significant impact on cost reduction. The method can therefore extremely complicated underground water treatment. The water arriving at the factory, has been naturally purified, need not, optionally, fining on activated carbon and a disinfection (AGC, and/or ozone, and/or chlorine) prior to its distribution. It is a raw water low reduced elements such as iron, manganese or ammonia, with a physical quality high, [...] to say with little suspended matter, having a low pollution index (fouling components), and with little mineral nitrogen (nitrate). The method therefore provides a true simplification of processing and the production of potable water at low costs.

The filter material resupplying basins, typically sand or gravel, can be loaded with oxides of iron and manganese after a use time along. It may then be necessary to replace a layer of about 20 cm of sand or gravel on the walls and the floor of the pool. This replacement occurs only after several years of operation, and passing a large volume of water on said layer of sand or gravel. This replacement remains much more easily and economically equivalent to a processing plant.

The method creates intermediate storage capabilities of conventional web or makeup. It allows taking advantage of the scavenging of the soil.

The method for concentrating the use of groundwater delineated areas on (about refueling systems), thereby simplifying the protection of abstractions of water by the constitution of basins hillsides restricted.

It is possible to provide several cycles of filtration in the under - ground followed by a pump to improve the characteristics of the water before its transfer to the processing plant.

Example application no. 1

Can be seen on Figure 2, a representation of the method implemented along the river Seine 3a. Water is pumped from a first edge of the Seine 3a. The resultant water, to the output of primary bores 2 in the under - ground 1 4 of the margins, is very different from the river Seine 3a itself. Benefit from a natural treatment in the reducing medium 4, it contains much less nitrates, and very few solids.

Then the water is moved through the array of existing mine drainage basins to resupplying 5 where it is stored some days prior its infiltration into the web. A second natural treatment in an oxidizing medium 6 will then transform ammonium and iron. It remains up from the water a second time using a branch borehole 7, for final processing factory, which will mainly be a refining on coal and disinfection (ozone and chlorine). The advantages of the implementation of the method are many. Achieved a significant improvement in the quality of drinking water produced by the processing plant, in particular a decline of nitrates, and a significant reduction, of about 75%, amounts of sludge treatment produced, investment cost reduced.

The protection of production zones of the field sensing against risks of polluting agricultural, municipal and industrial s is reinforced. The new configuration of the field sensing was used to confine pollution risks on some industrial piercings dedicated to the protection of the web which act as a hydraulic barrier.

A field of sensing is adjusted (creating parks hydrogeological, natural processing of water arriving at the factory). This solution provides a compromise with local actors that do consider more the activity of the operator as a threat to the development of their urban or industrial activities on decreasing the gap at land operation.

The investments are limited by the maximum reuse of existing and are linked mainly to the creation of secondary bores 7 and furnishings new sole plates resupplying 5. these investments remain significantly more modest than those of a sludge treatment.

Example application no. 2

The approach of the method according to the invention, which optimizes the torque/resource processing, is fully generalized.

Always in the vicinity of the river Seine, considering a subterranean resource whose quality is greatly degraded by ammonium. The method according to the invention will rehabilitate such resource.

According to Figure 3, a primary pump 2 is provided in the basement 1 in 4 of the river Seine 3a barge. Water will then be fed back by infiltration at the site of a gravel pit 5a, with natural nitrification and denitrification. The secondary pump 7 will use existing wellbores.

This solution will allow substantial investment savings with respect to a solution using biological denitrification/nitrification, or dropping the resource and a purchase water out perimeter.

This solution enables re-gravel pit and shores 5a 6a which do not require heavy arrangements to be used. The coexistence of an aerobic water column, and zones of organic sediments reducing make the site adapted both to the oxidation step for removal of iron, manganese and nitrifying ammonia that reduction reactions resulting in elimination of nitrates by biological denitrification.

With respect to a gait conventional water treatment, the invention simplifies the processing, with suppression of certain treatments. This results in the decrease of investments and minimizing the impact on the environment.

With respect to a conventional preventive approach, and in particular agricultural nitrates - screw, the method of the invention can stimulate the capabilities of purify existing in the environment. It therefore requires more technogenic pollution at the source, random and expensive.