Elements of ultrasonic flowmeter installation, model OMNI TDI 200H with test work results

Ultrasonic flowmeter works on the principle of transmitting and returning ultrasonic waves that pass through the liquid, ie. fluid, and is used to measure the speed of fluid movement through a pipeline or some other structural form of fluid movement. By knowing the velocity of the fluid and the cross-sectional area of the pipeline or other system, the value of the volumetric or mass flow can be obtained indirectly. Fluid flow measuring device model OMNI TDI 200H owned by the laboratory of the Biotechnical Faculty was used for the first time to measure the flow of purified water at the outlet of the plant device of the training center "Grmeč", built as a pilot plant. The paper will describe the role and importance of flow measurement by the conventional method and present the results of the trial operation of an ultrasonic flow meter, model OMNI TDI 200H

Antimicrobial activity of selected spice extracts on Escherichia coli, Salmonella spp., and Listeria monocytogenes

The study determined antimicrobial activity using the Disc-diffusion method and extracts of three plants: garlic (Allium sativum L.), turmeric (Curcuma longa L.), and parsley (Petroselinum crispum L.) on Escherichia coli, Salmonella ssp. and Listeria monocytogenes. These pathogens have attracted the attention of numerous agencies and researchers, because of the negative impact on food and human health - and because of the impact of disease development on the economy. These studies are necessary and represent potential natural antimicrobial drugs, and due to the resistance of bacteria to known antibiotics, there is a constant increase in global consumer demand for natural ingredients. The tested plant extracts showed excellent antibacterial activity in all three replicates on Escherichia coli with an average inhibition zone of 21,86 mm and were characterized as ***S - sensitive for the mentioned bacterium.  With an average zone of inhibition of 19,052 mm, Curcuma longa showed the strongest effect on the tested bacterium Salmonella enteritidis, which tells us that this bacteria is very sensitive to the extract of the mentioned plant. The study identified zones of inhibition of very low values (˃ 8 mm) in all three tested extracts: Allium sativum L., Curcuma longa L. Petroselinum crispum L., and Listeria monocytogenes

Effectiveness of domestic wastewater treatment in the “Grmeč” teaching center using pilot - scale constructed wetland as unconventional method

Environmental care, higher requirements for quality of effluent, high cost of conventional wastewater treatment, and increased energy costs required for their work, have led scientists to more comprehensive research on a possibility of using a constructed wetland in wastewater treatment technology. Constructed wetlands are artifi-cially shaped swamps with the aim of creating conditions conducive to the purification of wastewaters flowing through them. They are used for treatment of municipal wastewater from small settlements and a small industrial facility, as well as other types of wastewater. The educational pilot - scale constructed wetland on which the research was conducted is located in the area of Bihać municipality, on a plot used by the Biotechnical Faculty in Bihać. The pilot - scale constructed wet-land for wastewater treatment covers an area of 20 m2 and is dimensioned for 10 equivalents of population. In this research we have examined the effectiveness of domestic wastewater treatment in the "Grmeč" Teaching Center using pilot - scale constructed wetland. Plants planted in the constructed wetland were Typha latifolia and Phragmites australis, and the sub-strate was made of sand and pebbles of different granulations. The recipient of purified wastewater is the Drob-nica stream, which is about 10 m away from the site. The research was conducted in May, with the flow varied depending on a weekly student workload. Efficiency of purification using constructed wetland depended on flow rate and organic wastewater load, ranging from 37.15% at a minimum flow of 9.89x10-6 m3/s and HPK values of 35 mgO2/L, up to 89.48% at the highest flow value of 2.51x10-5 m3/s, and HPK values of 189 mgO2/L. The highest concentration of ammonia in the influent was 145.62 mg N/L, and the lowest concentration of ammonia in the effluent was 6.31. mg N/L

JAPANESE KNOTWEED (REYNOUTRIA JAPONICA) AS A PHYTOREMEDIATOR OF HEAVY METALS

Recently, plant remediation techniques - phytoremediation - have been developed. Japanese Knotweed (Reynoutria japonica), is an invasive species with negative impacts on the environment and the economy. In order to assess the tolerance of highly invasive weeds to heavy metals, an experiment was conducted in which this plant was grown in control soil and in soils contaminated with different concentrations of Pb, Cd. The content of heavy metals in the soil did not eliminate the ability of Reynoutria japonica roots to regenerate. In soil contaminated with any concentration of Pb, the shoots of this plant grew at a similar rate as the control plants, and had the same morphological characteristics. Higher concentrations of cadmium and lead Cd (100, 200 mgkg-1), Pb (2000 mgkg-1) have extended rhizome regeneration compared to control plants. In soils contaminated with lower concentrations of Cd or Pb shoots grew at a similar rate as control plants. Chemical analysis of heavy metal content showed that this weed accumulated large amounts of metals when grown in soil contaminated with heavy metals A relatively high intake of Cd, aboveground plants. At a cadmium concentration of 100 mg kg-1, more than 537 times the amount of cadmium accumulated in the aboveground part of the plant, as opposed to that in control. The ability of Japanese Knotweed (Reynoutria japonica), to regenerate from parts of the rhizome, to grow and develop under stressful conditions in the presence of heavy metals indicates a high tolerance to heavy metals. Key words: Japanese Knotweed (Reynoutria japonica), phytoremediation, heavy metal accumulatio

The potential of corn (Zea Mays) for phytoremediation of soil contaminated with heavy metals

Heavy metal pollution is a significant environmental problem and has a negative impact on human health and agriculture. Phytoremediation has recently emerged as an efficient heavy metal remediation technology. To examine the phytoremediation potential, an experiment was conducted, where the influence of high and low concentrations of heavy metals, lead, cadmium and zinc (Pb, Cd and Zn) on the phenological characteristics of corn (Zea mays), as well as their accumulation in the underground and aboveground part was monitored. The experiment was carried out in outdoor conditions in pots in which corn was planted and the soil was contaminated with heavy metals in concentrations below and above the maximum allowable concentration prescribed by the Ordinance. The experiment lasted 45 days. By processing the results, statistically significant differences in plant development were determined.The highest concentration of Zn was recorded in the aboveground part of the plant, the stem in the amount of 24.443 mg/kg, and the lowest concentration in the leaf 0.216 mg/kg. The highest concentrations of Cd and Pb were recorded in the root, for lead 26.610 mg/kg and in the stem for cadmium 30.490 mg/kg, which is a statistically significantly higher established value compared to other parts of the plant

FISH CANNING WASTEWATER TREATMENT IN SEQUENCING BATCH REACTOR WITH ACTIVATED SLUDGE

The biological performance of flocculent sludge in sequencing batch reactor for the treatment of fish canning wastewater was evaluated in terms of organic matter and nutrient removal by gradual increase of salt concentration in the nitritation-denitritation process. Salinity negatively affected the biological system performance in a way that reduced organic and nutrient removal. The removal efficiency of organic matter and nitrogen showed good performance below 20 g NaCl/L, while phosphate accumulating organisms activity was deteriorated and declined during whole experiment. Nitrogen removal occurred as ammonium oxidation with nitrite accumulation. Nitrite reduction was not affected by salt concentration

Effectiveness of domestic wastewater treatment in the “Grmeč” teaching center using pilot - scale constructed wetland as unconventional method

Environmental care, higher requirements for quality of effluent, high cost of conventional wastewater treatment, and increased energy costs required for their work, have led scientists to more comprehensive research on a possibility of using a constructed wetland in wastewater treatment technology. Constructed wetlands are artifi-cially shaped swamps with the aim of creating conditions conducive to the purification of wastewaters flowing through them. They are used for treatment of municipal wastewater from small settlements and a small industrial facility, as well as other types of wastewater. The educational pilot - scale constructed wetland on which the research was conducted is located in the area of Bihać municipality, on a plot used by the Biotechnical Faculty in Bihać. The pilot - scale constructed wet-land for wastewater treatment covers an area of 20 m2 and is dimensioned for 10 equivalents of population. In this research we have examined the effectiveness of domestic wastewater treatment in the "Grmeč" Teaching Center using pilot - scale constructed wetland. Plants planted in the constructed wetland were Typha latifolia and Phragmites australis, and the sub-strate was made of sand and pebbles of different granulations. The recipient of purified wastewater is the Drob-nica stream, which is about 10 m away from the site. The research was conducted in May, with the flow varied depending on a weekly student workload. Efficiency of purification using constructed wetland depended on flow rate and organic wastewater load, ranging from 37.15% at a minimum flow of 9.89x10-6 m3/s and HPK values of 35 mgO2/L, up to 89.48% at the highest flow value of 2.51x10-5 m3/s, and HPK values of 189 mgO2/L. The highest concentration of ammonia in the influent was 145.62 mg N/L, and the lowest concentration of ammonia in the effluent was 6.31. mg N/L

Co-composting of Sewage Sludge, Green Waste, and Food Waste

Rapid population growth requires more intense production of food industry, with two major consequences: significant amount of food processing residues and more sewage sludge originating from biological wastewater treatment plant. Sludge is a big concern for the disposal for wastewater treatment plant. The European Union makes an effort regarding the reduction of organic fractions disposed at a landfill. Composting is a cost-effective and ecological-friendly alternative for managing biodegradable organic fractions. Experiments of co-composting of sewage sludge, green waste and food waste, at carbon/nitrogen ratios 8.75, 18.00 and 24.90, were performed during three months by monitoring of temperature, pH, moisture, carbon and nitrogen proportion, carbon/nitrogen ratio, and germination index. The results showed that co-composting of sewage sludge, green waste and food waste is effective and results in the production of quality compos