Jānis Rubulis

ONLINE MEASUREMENT USAGE FOR PREDICTING WATER AGE FROM TRACER TESTS TO VALIDATE A HYDRAULIC MODEL

The tracer tests were performed using two approaches in the drinking water distribution network (1374 km) of Riga city, Latvia with the goal to verify and validate a hydraulic model build up in Epanet 2.0. The water is supplied for 700 000 inhabitants with average daily water demand of 1500 l/s from six different water sources. The each water source has a different electric conductivity (EC) value with the lowest numbers for deep groundwater 272±25 µS/cm (25 O C) and the highest for surface and artificially recharged groundwater 468±100 and 784±18 µS/cm, respectively. The significant difference for EC in sources was used as a natural tracer. The first measurement approach is based on field works during shut-down or start-up of WTP due to monthly working regime or yearly drainage of clear water tanks at stations located in the north-east of city. In total more than 20 locations in distribution network were used for measurements of EC from hydrants and/or at taps in buildings applying online conductivity meters 3400sc™ (Dr. Bruno Lange GmbH&Co, Germany) and condu::lyser™ (s::can Mestechnik GmbH, Austria) in predictable time interval. The second approach of tracer measurements was based on EC measurements in network within close distance to track minor changes of EC due to production/consumption ratio. The hydraulic model of Riga city was validated in 8 nodes with the maximum age of 25:40 hours, while the distal nodes in model accounts for 60 hours. Results showed that in order to measure correct changes of trace element it is necessary to do it very close to transient pipes with high flow. The measurements of tracer near reservoirs in network are unpredictable due to proper mixing of water. The approach of measurements with two online instruments in close distance (up to 5 km) to track minor changes of EC can be useful for validation of hydraulic models. However, the statistical analysis (z-test) of this method showed significant difference between mean values of measurements which can be explained with too many uncertainties (cross-connections of parallel lines, loops) for water mixing in city with population of 700 000 inhabitants.

Alkaline Activated Material for pH Control in Biotechnologies

By using industrial aluminium recycling waste, recycled silicate glass from outworn fluorescence lamp recycling plant, calcined kaolinite clay supplemented with alkali activator with different silicate modulus the new type of porous material for biotechnologic processes without the need for additional equipment for pH control was researched. This controlled-release system contains an alkali activated matrix in which NaOH crystals are encased. In this study ability to release NaOH per time in water according to material composition and structure were investigated. Three alkaline activated materials AAM 7.5, 10 and 12.5, with different alkali activator content were characterized.

Latvian Practices for Protecting Water and Wastewater Infrastructure

The Republic of Latvia has promulgated a number of laws that govern the national response to emergencies in water and wastewater.

Interpretation of Loose Deposits Motion in Drinking Water Distribution Network

The present study was designed to describe the turbidity curve obtained during planned unidirectional flushing in drinking water distribution system of a diameter 100-300 mm. The online measurements of flow and turbidity for cast iron (n=16), polyethylene (PE, n=7) and polyvinylchloride (PVC, n=4) pipe sections and calculations of hydraulic values indicated that the turbidity curve peaks appeared at the locations of bends, tees, narrow parts of the pipes etc viz. where increased hydraulic drops take place. The application of on-line measurements during the wash-out of loose deposits in both cases from one and two hydrants simultaneously, the calculations of average velocity (0.72 m/s, n=22) and shear stress (2.05 N/ m 2 , n=29) on pipe walls showed that the loose deposits in the pipes move according to plug-flow principle in a turbulent regime. The granulometric analysis of loose deposits showed that the average diameter ranged from <1-558.4 µm (n=16) and did not correspond to the cohesive nature and average surface area of loose deposits which was 48.864 m2/g (n=17) with lowest values for samples of PE and PVC pipe sections (1.684 m 2 /g) and highest for CI sections -148.991 m 2 /g. The analysis of X-ray crystalline phases of loose deposits indicated the predominance of goethite and quartz. The observations of peaks from turbidity curves fitted for junctions of pipe network are significant for modeling of loose deposit discoloration events in distribution network.