K CONSULTATION | design and engineering consultancy firm based in India for Water Treatment Plants and Solid-Liquid Separation

Kcon PMC Pvt. Ltd. is a 25 years old design and engineering consultancy firm based in India. We specialize in water treatment systems and solid-liquid separation. We work in private, industrial, municipal and government sectors. Our founders have a cumulative experience of seventy years in this field.

We have to our credit about 600 plants around the world

Jamshedpur (Tatanagar) ,Jharkhand, INDIA (Fig. 20)

The ‘River water works’ belongs to a prestigious giant steel manufacturing group (TATA Steel), which supplies the treated process water to their different units in the area. The existing plant was constructed in the year 1991, source being river Suvarnarekha in the southern part of state Bihar (Now Jharkhand). The existing plant consisted of two numbers of clariflocculators (35 mld each) with overall diam 40.0m, flocculation zone diam 17.5m and side water depth of 4.0m. The inlet works, which was common to both the clariflocculators, consisted of a receiving chamber, an elevated channel with parshall flume and a mechanical rapid mix unit. Clarified water from both the clariflocculators was collected in the peripheral collection launder and then was delivered to the storage tank through a common discharge pipe.

Increase in demand for the clarified water by another 70 mld was envisaged by the management in the year 1999. It was decided to augment the existing plant (clariflocculators) from 70 mld to 144 mld by using the new techniques and with minimum structural work. The work was executed in the year 1999-2000.

Out of the total available clarification area of 1000sqm per clariflocculator, tube modules were placed in the flow path covering area of 550sqm (net surface loading 5800 lph/sqm). The modules were placed in a form of an annular ring adjacent to the outer wall of clariflocculator. A unique arrangement in the form of radial trusses, 32 nos, each having a span of 5.90m supported the modules from bottom. These trusses were cantilevered from the outer RCC wall of the clariflocculator. The trusses also supported the mild steel partition wall at the end to form a circular tube clarification zone. The vertical support members of scrapper rake (which were obstructed by the tube modules) were relocated in the “dead zone” between the flocculator wall and the new partition wall. The cantilever part of the scrapper rake arm was structurally strengthened to sweep sludge from floor below the modules. Radial troughs fabricated out of mild steel were provided to collect the clarified water uniformly. The dead-end of the troughs were supported on the above described partition wall. The discharging-ends were supported on the existing peripheral collection launder.

Due to doubling of flow, the detention time of flocculation zone was reduced from 40 min to 20 min. The four numbers of slow agitators (per unit) suspended from the rotating bridge in the flocculation zone were modified to supplement additional velocity gradient ‘G’, so as to increase the degree of agitation and to maintain the desired ‘Gt’ product. The area of paddles was suitably increased to achieve this. The existing drive units were found to be capable of handling the additional power requirement and hence were retained after overhauling only.

Due to doubling of flow the velocity in the inlet pipes to clariflocculators (buried under ground) was increased from 1.0m/sec to 2.10m/sec. To accommodate the rise in head, the existing inlet works was required to be discarded. A new inlet works comprising of a receiving chamber, a measuring (cum rapid mix) weir and a mixing basin was constructed as the only new civil construction. The rapid-mix weir was designed to have a freefall of 0.50m to impart velocity gradient of 800-1000 m/sec/m. The turbulence generated on the downstream side of weir was confined to a small basin having detention time of 2 sec. The coagulant feeder pipe spanning the width of basin (having perforations at the bottom) was located above the nappae of the weir. The existing rapid-mix unit was converted to flow distribution chamber with isolation gates for each clariflocculator.

On the down stream side of clariflocculators, new openings were created in the collection launders, diametrically opposite to the existing ones to restore the capacity of channels. Additional pipelines were laid to convey the water to the storage tanks.

The total headloss in the existing system (from receiving chamber to storage tank) was 0.90m, while the headloss in the augmented system was 2.40m. The additional headloss was mainly contributed due to the rapid-mix weir and the overloaded underground pipes to clariflocculators.

The project was completed in six months. The modifications were carried out in fair weather season when raw water turbidity was less than 20 NTU. Each clariflocculator was isolated one at a time for duration of one month to complete the internal modifications. Raw water was required to be bypassed directly to the storage tank only for eight days, during which the new inlet works was structurally connected to the distribution chamber (existing mechanical rapid-mix unit). During trial runs in July-August 2000, the clarified water turbidity of less than 10 NTU was achieved against raw water turbidity of 100 to 400 NTU with only PAC (Poly Aluminium Chloride) as a coagulant. Contract value of the job was INR.16 million ( US $ 0.36 million) with a net saving of 50% in the capital cost had a new plant of same capacity been constructed. All the existing mechanical equipment were also thoroughly overhauled during up-gradation, increasing their life substantially.

5/87 Shubhankaroti, Vidya Vihar colony, Nasik Road, Nashik 422101, Maharashtra, INDIA
Tel : +91-253-6450126, 2456655 Email : kcon@vsnl.com, info@kconpmc.com
website : www.KconPMC.com