Evaluation of the trophic level and self-cleaning ability of small flows by hydrochemical indicators (through the example of the Rpen River)

Aim. Assessment by nitrification index values of the level of trophicity and toxicity for aquatic organisms in the waters of a small watercourse in an urbanized area by the content of nutrients in the water and its selfcleaning ability.Materials and Methods. The concentration of compounds of nutrients in the waters of the river was determined using the "Kapel 104T." system of capillary electrophoresis. Water was sampled for analysis according to GOST R 51592- 2000. The water content of readily oxidized organic compounds was assessed by the magnitude of permanganate oxidizability (PND F 14.1; 2.4.154-99) and difficultly oxidized compounds by the magnitude of the chemical oxygen consumption (RD 52.24.421-2012). Assessment of the water trophic level was evaluated by measuring the content of various forms of mineral nitrogen and mineral phosphorus. The aggregation index characterizing the toxicity of various forms of mineral nitrogen to aquatic organisms was calculated by their ratio to MPC for fishery reservoirs. The nitrifying ability of river waters was estimated by the value of the nitrification index (Initr.), calculated by the ratio of the concentration of nitrogen of nitrates in water to the sum of the concentrations of various forms of mineral nitrogen and the self-cleaning ability by the values of the nitrification index.Results. In terms of the aggregation index, water at all sampling points was found to be toxic. The river ecosystem is characterized by a weak ability to cleanse itself and a weak nitrifying ability, which is associated with the influence of numerous cyanotoxins on the microbiocenosis of the watercourse and filtration organisms.Conclusion. It was shown that the most sensitive indicator of trophicity of river waters is the concentration of the mineral phosphorus. Through measuring the ratio of the concentrations of mineral nitrogen to mineral phosphorus, it was established that blue-green algae (cyanobacteria), producers of cyanotoxins, dominate in the phytoplankton of the river in all the points studied.

Upgrading of Food Waste in-vessel Composting Process: Effects of Biochar-rich Digestate Addition

Nowadays, Tunisia faces challenging environmental and energic issues which concern mainly the implementation of an appropriate solid waste management system dealing with the high production of biowaste in one hand and the increased need for water and energy resources in the other hand. Therefore, the current study intended to develop a technical concept on closed cycle ‘biowaste to bioenergy’, treating mainly food waste (FW) through combined biological processes. In this approach, FW anaerobic digestion (AD) residue was destined to feed FW in vessel-composting as a valuable input material. To this end, the produced digestates from amended and unamended anaerobic reactors were entirely examined to select later the most appropriate AD-effluent. Therefore, the identification of the convenient digestate was achieved based on technical criteria ; moisture content (MC), C : N ratio and heavy metals concentrations. The findings showed that the digestate obtained from different digesters was characterized by a high moisture content which inspired its utilization as an unconventional moisturizing agent (MA) reducing the fresh water consumption during the composting process. Because of the high C : N ratio, relatively significant rate of the needed macro and micro-nutrients, the exploitation of biochar-rich digestate was recomended to be used as an unconventional MA in one hand and an aerobic co-substrate booster in the other hand. Results showed that D3 addition promoted the composting process performance comparing to the blank test (A1). Indeed, the thermophilic phase of the amended reactor (A2) lasted 15 days and reached higher temperatures of about 67 °C, while the unamended one (A1) was characterized by a thermophilic temperature of around 63 °C indicating that the end-products were of a pathogen-free compost. When it comes to the physico-chemical factors examined demonstrating that the biological conditions were sufficiently developed. The findings showed overall decreasing profiles during the composting period for moisture, C : N ratio as well as nitrification index (NI). From the quality-point of view, it was found that heavy metal concentrations had lower limits than those values set by German standards. Moreover, all the compost samples appeared to be stable and classified as class IV and V end-product.

From anaerobic to aerobic treatment: upcycling of digestate as a moisturizing agent for in-vessel composting process

In Tunisia, there are crucial challenges facing both urban and rural areas, the most prominent of which are the production of organic waste, the need for waste treatment, the demand for water and energy and the need for a circular economy. To this end, the study was designed to develop a technical concept on closed cycle ‘biowaste to bioenergy’ treating, basically food waste (FW) through combined biological processes. In this approach, the generated digestate from FW anaerobic reactors was used successfully as a moisturizing agent for FW in-vessel composting. Four types of digestate were examined to be used as moisturizing agent (MA). The selection of the appropriate MA was achieved based on technical criteria; moisture content (MC), C:N ratio and heavy metals concentrations. The findings showed that the digestate obtained from anaerobic co-digestion of food waste and wheat straw (D1) was the most efficient AD-effluent to be added. In terms of composting process performance, the thermophilic phase of the amended reactor (A1) lasted 16 days and reached higher temperatures of about 72 °C, while the unamended one (A1) was characterized by a thermophilic temperature of around 66 °C indicating that the end products were of a pathogen-free compost. When it comes to the physico-chemical factors examined demonstrating that the biological conditions were sufficiently developed. The findings showed overall decreasing profiles during the composting period for moisture, C:N ratio as well as nitrification index (NI). From the quality-point of view, it was found that heavy metal concentrations had lower limits than those values set by German standards. Moreover, all the compost samples appeared to be stable and classified as class IV and V end product.

From Anaerobic to Aerobic Treatment: Upcycling of Digestate as a Moisturizing Agent for in-vessel Composting Process

In Tunisia, there are crucial challenges facing both urban and rural areas, the most prominent of which are the production of organic waste, the need for waste treatment, the demand for water and energy and the need for a circular economy. To this end, the study was designed to develop a technical concept on closed cycle ‘biowaste to bioenergy’ treating, basically food waste (FW) through combined biological processes. In this approach, the generated digestate from FW anaerobic reactors was used successfully as a moisturizing agent for FW in vessel-composting. Four types of digestate were examined to be used as moisturizing agent (MA). The selection of the appropriate MA was achieved based on technical criteria ; moisture content (MC), C : N ratio and heavy metals concentrations. The findings showed that the digestate obtained from anaerobic co-digestion of food waste and wheat straw (D1) was the most efficient AD-effluent to be added. In terms of composting process performance, the thermophilic phase of the amended reactor (A1) lasted 16 days and reached higher temperatures of about 72°C, while the unamended one (A1) was characterized by a thermophilic temperature of around 66°C indicating that the end-products were of a pathogen-free compost. When it comes to the physico-chemical factors examined demonstrating that the biological conditions were sufficiently developed. The findings showed overall decreasing profiles during the composting period for moisture, C : N ratio as well as nitrification index (NI). From the quality-point of view, it was found that heavy metal concentrations had lower limits than those values set by German standards. Moreover, all the compost samples appeared to be stable and classified as class IV and V end-product.

Indicele de nitrificare a ionilor de amoniu în apele din fluviul Nistru

The paper presents the fluctuations of the river Dniester Water Nitrification Index, which denotes that downstream of Naslavcea village the nitrification process is intensely (98%), similar to that calculated according information of 2016-2019 years, and towards Palanca village is of 72-79%. Initrif of river Dniester water has a negative correlates with COD-Cr and BOD5, being evidenced the influence on the nitrification process of chemical and biochemical degradable substances, which is attes

Optimization of Food Waste and Biochar In-Vessel Co-Composting

As bulking agents (BA) affect the composting process, this work examined the impact of combinations of different organic components in order to obtain an efficient co-substrate for food waste (FW) in-vessel composting. To boost the occurrence of microorganisms inhabiting the compost, mature compost was firstly coupled with wheat straw, added to FW, and considered as a control (BC0). Then, two trials (BC10, BC20) including 10% and 20% of biochar were monitored. The results indicated that the temperature of the amended bioreactors was notably increased compared to the unamended one. Thermophilic temperatures were achieved at 14, 34, and 78 h after the experimental setup for BC20, BC10, and BC0, which lasted for 14, 17, and 12 days, respectively. When it came to an assessment of maturity and stability, the quality of the compost was evaluated against several indicators and compared with the compost quality standards of the UK, France, Canada, the USA, Poland, and Germany. BC10 illustrated a high-quality product in relation to the heavy metal concentration, a C:N ratio which reached 14.97, an AT4 which was lower than 6 (4.36 mg O2/g TS), and a nitrification index of 2.61 (<3). Consequently, the addition of 10% of biochar as a co-substrate showed an improvement of the process evolution and the characteristics of the biofertilizer produced.

Aerobic Municipal Solid Waste Compost Quality According to Different Layers of Composting Bioreactor

Composting is one of the methods of solid waste management (SWM) where the organic component of solid waste stream is biologically decomposed under controlled conditions. A bioreactor tank was designed to contain 59.2 kg of mixed organic municipal solid waste, the organic matter was degraded under aerobic condition for 30 days. The tank was 45 cm in diameter, 130 cm total height and a 0.2 cm wall thickness. Three circular openings with screwed cover having diameter of 12 cm were leveled at (20, 40 and 80) cm respectively to withdraw samples. Temperature, moisture and pH were measured for three layers as process guideline indicators. Maximum temperature ranged between (34.79 to 46.91) ºC. Initial pH value was 6.53, ended within a range of (7.4 to 7.44). Chemical analysis for the composts in the three levels proved that the final C/N ratio ranged between (13.8 to16.1), TOC ended within a range of (17.33% to 25.24 %), final nitrification index (N-NH4/N-NO3) ranged between (0.22 to0.31), final of P% ranged between (0.89% to 1.23%), final of K% ranged between (1.69% to 1.81%) and results of germination index (GI %) ranged between (76.54%, to 88.35%) for three layers respectively. At the close of the experiment results proved that aerobic in-vessel composting could reduce the large amounts of wastes by 40% as a total mass. A satisfactory degree of decomposition was apparent in all levels, and the material was characterized by a pleasant earthy odor, and the obtained compost can be classified as mature compost. In conclusion, the three different layers do not have much effect on the quality indices of the final product.

Evaluation of Heavy Metals Content in Simulated Solid Waste Food Compost

Composting is one of the solid waste management (SWM) methods where the organic component decomposed biologically under controlled conditions. In this study, a 0.166 m3 bioreactor tank was designed to compose 59.2Kg of simulated common municipal solid food waste having a bulk density, organic matter, organic carbon, pH, nitrogen content, C/N and nitrification index (NH4-N/ NO3-N) of 536.62 kg/m3, 62.34%, 34.76%, 6.53, 1.86%, 23 and 0.34 respectively. The bioreactor operated aerobically for 30 days, and anaerobically for 70 days, until the end of the composting process. Results proved that the composting process could reduce the mass of the waste by 69%. Nitrogen content, C/N, nitrification index, NPK, and germination index (GI) were found to be 1.52%, 14.54, 0.31, 1.52%, 1.53%,0.85 % and 85.5% indicating that the obtained compost is stable and mature according to the standards. Twelve heavy metals of Zinc (Zn), Cupper (Cu), Molybdenum (Mo), Zirconium (Zr), Strontium (Sr), Rubidium (Rb), Manganese (Mn), Scandium (Sc), Iron (Fe), Titanium (Ti), Calcium (Ca) and Potassium (K) were detected by using Niton (XRF) device. Results of Cu and Zn were within the limits of the standards, while the rest were considered acceptable as standards did not restrict them.