14 The Open Hydrology Journal, 2010, 4, 14-18 1874-3781/10 2010 Bentham Open Open Access Study of the Flocculated Particles Sedimentation Assisted by Microcomputer D. Benouali 1 , S. Kacha 2, *, S. Kherici 1 and N. Benabadji 3 1 Département de chimie, USTOran, BP 1505, EL-Mnaouer Oran (Algeria) 2 Laboratoire des Matériaux et systèmes Réactifs (LMSR), Université de Sidi-bel-Abbes (Algeria) 3 Département de physique, USTOran, BP 1505,El-Mnaouer Oran (Algeria) Abstract: Sludge known as waste products, collected during various stages of water treatment, are fluids containing sus- pended solid particles in water. Sedimentation velocity of these particles is generally determined using batch settling tests. This velocity is a determining parameter in dimensioning and controlling the thickeners. Realization and contribution to the automation of a simple tool for such tests is the subject of this work. The used column (H: 2.30 m, D: 0.20 m) was provided with infra-red sensors, to quantify the total suspended solid particles (TSS) in water. The automated experimen- tal device avoids the recourse to the slow and limited conventional gravimetric method. The study of the settled particles becomes faster and furthermore by automation of the TSS measurements, it is possible to carry out the data acquisition di- rectly on PC via an adequate interface. Key Words: Suspended particles, Sedimentation velocity, flocculation, Infra-red sensors, Data acquisition. 1. INTRODUCTION The water treatment and purification process generates sludge, which is made up of inorganic and organic com- pounds that are soluble or colloidal, agglomerated by addi- tion of coagulants and flocculating agents. The flocculated sludge sedimentation is not a simple operation to model and cannot substitute the experimental batch-settling tests [1]. However, several recent works [2-4] suggest many formulas which need experimental data for their checking. This be- cause, the experimental study of the sludge sedimentation using static or dynamic settling tests must provide all the essential data. Thus a large number of data, carried out by on-line measurements, is required to correct the mathemati- cal models in this field. For the automation of the batch set- tling tests, the major problem is the on-line measurement device [5]. In practice, according to Wren [6], the character- istics of the suspended particles in water can be quantified by optical methods using transmission and back-scattering of the visible, the infra-red or the laser radiations. At the moment, the development of such sensors interests many researchers. For example, the infra-red sensor was described and used for the characterization of activated sludge, by Urrutlkoetxea and Garcia-Heras, since 1993 [7]. Nowadays, these sensors are used, in real applications, for the development of the data acquisition system and control of the sedimentation process [8-10]. But, the fooling of the sensor during the measurements remains a true obstacle [11,12]. This work proposes some discussion about produc- ing an infra-red sensor and a data acquisition chain able to *Address correspondence to this author at the Laboratoire des Matériaux et systèmes Réactifs (LMSR), Université de Sidi-bel-Abbes (Algeria); Fax: +213 48 54 43 44 ; E-mail: smail_k@yahoo.fr provide a large number of variables concerning the TSS evo- lution, according to the column depth and time. 2. MATERIALS AND METHODS 2.1. Batch Settling Tests Device The general diagram of the batch settling tests devise, used in this work, is presented in Fig. (1). The column is made of PVC and has the following di- mensions: height 2.30 m and diameter 0.20 m. To carry out water sampling at each level, the column is equipped by three valves superimposed, 0.60 m apart, and three infra-red sensors (Fig. 2). The infra-red captor is able to give an analogical signal allowing the quantification of TSS, accord- ing to the time and depth. This system can describe correctly the flocculated particles sedimentation, by the acquisition of the analogical signal, communicated to the PC, via a mul- timeter MAS-34 at exit RS 232. The software which ensures the acquisition (DDM view version 2) is commercialised with the multimeter. It is known that the turbidity of water is in relationship with the amount of TSS, thus the amount of suspended solid particles contained in water, can be deduced by measurements of the infra-red light quantity, transmitted and back-scattered by the particles. The data acquisition of turbidity was carried out using a simple device, made in the laboratory. It consists of two infra-red led, the first is a transmitting led, while the second is a receiving led (Fig. 2). The infra-red emitter (940 nm) is connected to an AC power source 220 V converted to a DC 12 V. 2.2. Flocculated Sludge for the Batch Tests The sludge used in this work was prepared using Sarno dam surface water in Sidi bel-Abbès, Algeria, by applying the same procedure of treatment clarification used in the dam