New prototype equipment with UV radiation for water purification processes.

Volf, Irina ; Badea, Cristinel ; Ciobanu, Bogdan 等

1. INTRODUCTION

Water represents one of the critical resources concerning the sustainable development, both by its position of a base resource and also for its contribution in generally development for life support. Water is essential for industrial, agricultural, services development and for energy production, for ecosystems conservation or to ensure a good population health. In September 2005, the UN Summit has launched an appeal for helping in course of development countries to prepare the Integrated Water Resources Management and also to establish efficient water resources utilization plans as well defined parts of national development strategies with the aim to fulfill Millennium Development Goals. Most of these objectives (extreme poverty and famine eradication, durability of environment assurance, global partnership development for sustainable development) are in strong connection with water supply recycle and also with control and risks minimization due to pollutants sloop in aquatic environment, /UN Millennium Project Task Force on Water and Sanitation, Final Report, 2005/. Development strategies discussed at UN Summit has raised an important challenge: how to prepare the Millennium Development Objectives at national level in order to take into consideration water resources in such strategies. A general definition of Integrated Water Resources Management was given by Global Water Partnership through the Technical Committee: "Integrated Water Resources Management is a process which promote the coordination the development and the management of water supplies, durable utilization of land and other resources with the aim to maximize the economic results and social welfare in an equitable manner without compromising the durability of vital ecosystems." /GWP, 2004/. This definition implies aspects which aim: the soil, the water resources (underground and surface water), riverbank, coastal and maritime areas, upstream and downstream users, and also aspects which target human capacity of using and benefit in a durable way of physical resources.

Over the last decades the use of the ultraviolet radiation for the disinfection (bacteria, viruses and other water pathogens) has increased remarkably. World widely, the need of cleaning water is continually growing; the responsibility of the water companies is the supply of water of the highest quality possibly (according to the Guideline 98/83/CE).

International general tendencies are the elimination of chemical substances and boiling process in water purification and use of installations with ultraviolet radiations (Carona, 2007).

The main preoccupations and achievements on the world plane are directed to installations using as a purification procedure the exposure of water to ultraviolet radiations. This category of installation is already produced and sold by companies such as: Berson Milieutechnick BV--Holland, Wedeco AG, Atlantic Corporation, Delta UV Germany, Willand UV Systems Ltd Great Britain and so on.

There are not known systems with GSM signal that can transmit the main data regarding the functioning of the UV installation, nor procedures of automatic tracing of the weakest lamp in order to replace it.

The degree of novelty of the prototype proposed consists in elimination of the chemical substances used in water disinfection, quick and easy installing, possibility of a quick service, efficiency in the destruction of micro-organisms; GSM distance monitoring, good hydraulic behaviour.

2. TECHNOLOGY USE

The basic diagram of the installation is presented in figure 1.

The main body of the installation consists of a 120 mm diameter stainless steel pipe, 900 mm long. Inside it, there are mounted three quartz tubes at 1200, each containing an UV lamp with a power of 55 W. Water is flooding in inside the pipe and exterior to the quartz tubes being submitted to UV discharges. Three UV sensors are mounted outside the stainless steel pipe for the control and diagnose of UV discharges.

In case of bigger water flows the UV reactors can be connected in batteries of three or more reactors placed in parallel (fig. 2).

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

Further on, there is presented an installation of the UV device in a system with collection and treatment of the drinking water (fig. 3).

The general view of equipment is presented on the figure 4.

Using this equipment the following main problems will be solved:

--comparative study of micro-organisms elimination through classic techniques of disinfection (in chlorine presence or his derivatives) and by UV treatment (Volf & Teodosiu, 2008);

--study concerning the factors that affect the disinfection process with UV radiation;

--testing the performances of proposed technological solution in water contaminated with different micro-organisms (levures and bacterium)

--demonstrate the possibilities and utilities of application of proposed solution by testing at an industrial level the proposed model.

For the proposed prototype we realize a flow simulation through hydraulic circuit using finite element method (Lewis, 2004) and (Dhaubhadel, 1994). The aim of this simulation was, at one hand, to estimate the total pressure loss when fluid pass through prototype and, at the other hand, to estimate the velocity of flow in UV radiation area. It's important to estimate this velocity because starting from this value we can calculate the pass-through time of a micro-volume of fluid through the UV radiation area, time that is directly connected to the efficiency of micro-organisms inactivation process.

In order to realize the simulation, the model of hydraulic circuit and the finite element (wedge type) network, was created.

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

The enforced boundary layer conditions was the average flow speed (v=1.4 m/s) on the inlet, corresponding to a flow rate Q=4 l/s, and zero flow speed (v=0 m/s) in vicinity of pipe boundary.

The FEA reveals a total pressure loss Ap=0.16 105 Pa. That means a total head loss [DELTA]h=1.63 m[H.sub.2]O (fig. 5). Considering the whole circuit like a local hydraulic resistance we obtain a global hydraulic loss coefficient [zeta]=16.3 for the proposed prototype.

The fluid flow speed in UV radiation area is, according to the analysis, about 0.9/1.1 m/s.

The finite element analysis applied to the hydraulic circuit reveals two important conclusions:

--global hydraulic loss coefficient is similar like the one of a hydraulic valve with the same diameter (that means a very good value);

--pass-through time of a micro-volume of fluid through the UV radiation area is at least 1 sec.

3. CONCLUSIONS

The technical impact can be evaluated through the introduction of a new non pollutant technology which does not change the taste and smell of water, a technology which does not need chemical additives and uses a series of small and easy maintainable equipments with lower costs.

The economic and social impact can be evaluated as follows:

--risk of illness by consuming drinking water will be diminished

--necessary costs for assembly, maintenance and exploitation for this type of equipments will be reduced

--water producer productivity will be increased

--acquired experience will improve the ability of the producer of the equipment to develop a large range of such equipments.

4. REFERENCES

Carona, E., et al (2007). Impact of microparticles on UV disinfection of indigenous aerobic spores, Water Research 41, 4546-4556.

Dhaubhadel M.N., Habashi W.G., Engelman M.S., (1994). Advances in Finite Element Analysis in Fluid Dynamics, International Mechanical Engineering Congress and Exposition, Chicago, Illinois.

Lewis R.W., Nithiarasu P., Seetharam K., (2004). Fundamentals of the Finite Element Method for Heat and Fluid Flow, Wiley Publisher.

Volf, I., Teodosiu, C., (2008). Inactivation of some bacteria and fungi using a UV radiation system for treatment of drinking water, le Cinquieme Colloque Franco-Roumain de Chimie Appliquee, Bacau, 2008.