Batch fermentation of black tea by kombucha: A contribution to scale-up

Local domestic Kombucha was used in fermentation of 1.5 g L-1 of black tea (Indian tea, " Vitamin ", Horgoš, Serbia and Montenegro), sweetened with approximately 70 g L'1 of sucrose. Inoculation was performed either with 10% or 15% (v/v) of fermentation broth from previous process. The fermentation was conducted in geometrically similar vessels with 0.4 L, 0.8 L, 4 L and 8 L of substrate, at 22±1 °C for 28 days. The samples were analyzed after 3, 4 5, 6, 7, 10, 14 and 28 days, so that their pH values, content of total acids sucrose, glucose and fructose contents, as well as contents of ethanol and vitamin C were determined. Based on the experiment design, the response surface for the product pH, as a function of time, beverage volume and inoculum concentration, was defined in the form of a second-order polynomial. From the obtained response surface, a formula for scaling-up of the process was derived

Ispitivanje koagulacione aktivnosti prirodnih koagulanata ekstrahovanih iz različitih sorti pasulja

Coagulation and flocculation by adding chemicals are the methods that are usually used for removal of water turbidity. This study is concerned with the coagulation activity of extracts of various strains of bean. The aim was to ascertain if bean varieties influence coagulation activity. Active components were extracted from 1 g of ground sample with 100 ml distilled water. Contents of dry matter and nitrogen were specified in the solid samples, and the content of soluble nitrogen was determined in the extracts. These data were used to calculate the efficiency of extraction of nitrogen-containing compounds. The coagulation activity was assessed by jar test using synthetic turbid water, of the initial pH 9 and turbidity 35 NTU. The jar test was carried out by adding different amounts of extracts to model water, and stirring the content. After sedimentation for 1 h, residual turbidity was determined by turbidimeter and coagulation activity was calculated. The increment of organic matter concentration after the coagulation was also determined. These experiments confirmed that extracts of all investigated strains of bean could be used successfully as natural coagulants.Koagulacija i flokulacija predstavljaju najčešće primenjivane metode za bistrenje vode, i uglavnom se izvode dodatkom hemijskih koagulanata. U ovom radu je ispitivana koagulaciona aktivnost ekstrakata dobijenih iz semena različitih sorti pasulja, a s ciljem da se utvrdi mogućnost njihove primene kao prirodnih koagulanata za uklanjanje mutnoće vode, i da se utvrdi uticaj sorte pasulja na koagulacionu aktivnost. Ekstrakcija aktivnih komponenti je izvedena sa 100 ml destilovane vode iz 1 g samlevenog uzorka. U čvrstim uzorcima je određen sadržaj suve materije i azota, a u ekstraktima sadržaj rastvorljivog azota, na osnovu čega je određena efikasnost ekstrakcije jedinjenja sa azotom. Za određivanje koagulacione aktivnosti ekstrakata izveden je džar-test, dodavanjem različitih doza ekstrakata model vodi, čiji je pH 9 i početna mutnoća 35 NTU. Nakon mešanja u određenom vremenskom intervalu, čaše su ostavljene da se njihov sadržaj istaloži, a zatim je u bistrom delu određivana mutnoća, i preko nje koagulaciona aktivnost. Takođe je utvrđen doprinos svakog od ekstrakata porastu sadržaja organskih materija u vodi nakon njenog bistrenja u odnosu na slepu probu, a preko permanganatnog broja. Ovim eksperimentima potvrđeno je da se ekstrakti svih ispitivanih sorti pasulja mogu uspešno primeniti kao prirodni koagulanti

The kinetics of chromium(VI) adsorption from water on some natural materials

This paper is concerned with the kinetics of chromium(VI) adsorption by wood sawdust, pulp, and Kraft lignin. In our previous works we determined adsorption efficiency of these adsorbents. In this paper we focused our attention on the influence of contact time on chromium(VI) adsorption from water by the same adsorbents. The analytical data were approached from the following kinetic models: First-order kinetic model, Parabolic diffusion model, Elovich model, and Modified Freundlich model. Elovich model was shown to be the best fit for the description of chromium(VI) adsorption. It was found that adsorption was the fastest on pulp and slowest on Kraft lignin

Investigation of coagulation activity of natural coagulants from seeds of different leguminose species

The ability of seeds of plants: Phaseolus vulgaris, Robinia pseudoacacia Ceratonia siliqua and Amorpha fruticosa, to act as natural coagulants was tested using synthetic turbid water. This water was prepared by adding kaolin into tap water, just before the test. Active components were extracted from ground seeds with distilled water. The coagulation ability of this extract was assessed by the use of standard jar test measurements in water with various initial turbidity. Investigation of these natural coagulants was confirmed their positive coagulation activity. Of all plants that have been examined, the seed extract from Ceratonia siliqua appeared to be one of the most effective coagulants for water treatment. A dose of 20 mg/l of this coagulant resulted in 100% coagulation activity for clarification of water with 17.5 NTU initial turbidity

Treatment of the liquid phase from the red mud disposal site of the aluminium plant in podgorica

The aim of this paper was to investigate the quality of the liquid phase (water) from the red mud disposal site of the Aluminium Plant in Podgorica. Based on theoretical knowledge and experimental results, the water from the red mud disposal site was refined, so that it could sluice in the recipient (Morača River). Refining of the water achieved the following: 1) reduction of environment pollution and 2) reduction of natural water consumption, which contributed to the preservation of a major environmental resource. The technological treatment of water from the disposal site was based on the selection of the optimal reagent for neutralization, separation of the solid products from that process and sluicing of the treated water into the recipient. The results obtained will be useful in the protection of potable well-water located in vicinity, south of the Aluminium Plant in Podgorica

The influence of different matrices on the nature and content of haloacetic acids precursors in ozonized water

This paper investigates the influence of different matrices (groundwater a realistic natural matrix and commercial humic acid solution a synthetic matrix) on the nature and content of haloacetic acid (HAA) precursors in ozonized water (0.4 to 3.0 mg O3/mg DOC; pH 6). Natural organic matter (NOM) characterization of the natural matrix showed it was largely of hydrophobic character (65% fulvic and 14% humic acids), with the hydrophilic fractions HPIA and HPI-NA at 12% and 9%, respectively. At approximately the same dissolved organic carbon (DOC) content of the investigated matrices (~10 mg /L), a greater degree of hydrophobicity was seen in the humic acid solution than in the natural matrix, resulting in a higher content of HAA precursors (559 ± 21 μg/L in the synthetic matrix compared to 309 ± 15 μg/L in the natural matrix). By applying different ozone doses (0.4 to 3.0 mg O3/mg DOC), the DOC content of the studied matrices was reduced by 6-22%, with a maximum process efficacy being achieved with 3.0 mg O3/mg DOC. Ozonation also lead to changes in the NOM structure, i.e. complete oxidation of the humic acid fractions in both investigated matrices. After oxidation, hydrophilic structures dominate the natural water matrix (65%), whereas the synthetic matrix has an equal distribution of hydrophobic and hydrophilic fractions (~50%). Changes in the content and structure of NOM during ozonation resulted in the reduction of the total HAA precursors content (63-85%, using 3.0 mg O3/mg DOC). Detailed analysis of the reactivity of the residual HAA precursor materials shows that ozonation using 3.0 mg O3/mg DOC reduced the reactivity of the NOM fractions in comparison to the raw water. By contrast, HAA precursor material present in the commercial HA solution was transformed after ozonation into other reactive compounds, i.e. precursors which originated from the fulvic acid and hydrophilic fractions. The results of the laboratory testing indicate that the application of ozonation can reduce the content of haloacetic acid precursors to some degree. However, in real applications of oxidative treatment in the preparation of drinking water, as well as the efficacy in reducing the total organic matter content, the nature of the residual NOM must also be taken into account, as it can include toxic reactive precursors to disinfection byproducts