Fully Automated Water Treatment System Successfully Installed in Tusnad
30 September 2005
Tusnad-Sat is situated in the Vally of the Olt Stream (river) at 672m altitude - one of the biggest natural reserves in Romania.
What else can be told about Tusnad? It is a small city surrounded by natural beauties, it is the largest seed-potato growing place in the country - and it is famous for its several mineral water springs .
The company APEMIN TUSNAD S.A. was founded in 1999 to exploit the mineral water sources of the Tusnad-Nou spring. Originating from the Harghita volcanic mountains the water quality is perfect and balanced in minerals and purity .
High Quality is the key objective of the young management team at Apemin Tusnad. The production is carried out under a strict quality control based on DIN ISO 9001:2000 and the recently introduced HACCP system. The natural spring water "Tusnad" meets the quality requirements in conformity with EEC directives regarding natural spring water production.
The management decided to launch a new spring water named IZVORUL ASCUNS - HIDDEN SPRING. The company recently purchased and installed a PALL filtration unit to meet the same quality requirements and to assure the quality of the pure source.
Pall Corporation enjoys a good reputation in water filtration. Pall water purification plants are used worldwide in water and soft drinks production. The systems have brilliant, proven performance and reliability.
On the basis of a 10 year trusted collaboration, the technical management once again decided in favour of Pall. Based on the process specification, quality requirements and water analysis provided by the customer a tailor-made stainless steel unit has been installed in February 2005. This tangential flow filtration unit successfully filters a volume of 15,000L per hour at a filtration temperature of 15 °C. It is possible to increase the output up to 20,000L per hour.
The system is designed for ease of operation. All plant operations are controlled via PLC. Operational parameters, such as flow rates, pressure, temperature and transmembrane pressure (TMP), are monitored and recorded automatically. The filtrate quality is detected online allowing process auto-stop, if the requirements are not met. Routine operations do not require manual operation of valves etc. and the fully automated system eliminates any potential problem caused by operator error.
During filtration water is pumped through a back-washable strainer directly into the system. The heart of the plant are Microza modules utilizing proprietary PAN (polyacrylonitrile) hollow fibres with a molecular weight cut-off of 80,000 Dalton. Each of the five modules is fed with an equivalent flow rate with an outside to inside flow. As a result, high filter areas can be achieved in relatively small systems. In contrast to conventional filtration the membranes are placed in parallel to the feed direction (tangential flow). Only clean liquid passes the membrane (permeate), while turbid matters and particles are retained. As a result of the flow, however, these materials and particles are not deposited on the surface. The retentate stream is returned to the feed tank. By these means the plant is operated at a recovery of more than 95%.
Due to the hydrophilic properties of the fibres, membrane fouling is reduced and flow capacity is enhanced. Moreover the membrane is resistant to bacteriological degradation and is characterized by exceptional mechanical strength and durability. The tight membrane structure with its narrow pore size distribution avoids penetration of any kind of contamination. Thus excellent removal of suspended solids is provided with filtered water turbidity of 0.04 to 0.05 NTU.
At a pre-set frequency the system will go through a reverse filtration cycle. By backwashing with a 2.5ppm sodium hypochlorite solution for about 60 seconds surface contaminants are removed restoring the modules. This cleaning process is also automated.
The customer is highly satisfied with the installation. The filter works in a reliable way concerning both quality and service life. By installation of a fully automated system labour costs are minimised. The high durability of the membrane permits extended operation including reverse filtration and chemical cleaning. The service life of the modules is expected to be more than five years. In case of replacement the costs will be moderate. Low energy consumption and the lack of consumables further contribute to cost savings.
