Fuel Characteristics and Phytotoxicity Assay of Biochar Derived from Rose Pruning Waste

The aim of this study was the characterization and evaluation of applicability as a soil amendment of biochar derived from rose pruning waste at different pyrolysis temperatures (200-500 °C) and process durations (20-60 min). The biochar properties were compared to the raw material. The biochars produced at 300 °C for 40 and 60 min demonstrated the best fuel properties. These variants showed high energy gain rates (77.6 ± 1.5% and 74.8 ± 1.5%, respectively), energy densification ratios (1.35 ± 0.00 and 1.37 ± 0.00, respectively), high heating values (24,720 ± 267 J × g-1 and 25,113 ± 731 J × g-1, respectively), and relative low ash contents (5.9 ± 0.5% and 7.1 ± 0.3%, respectively). Regarding fertilizer properties, such as pH value, ash content, heavy metal content, and pollutant elution, the biochars showed better qualities than the raw material. All tested biochar did not exceed the permissible values for heavy metals, including Cr, Cd, Ni, and Pb. The most optimal properties for soil amendments were noted for biochar variants of 400 °C for 40 min, 450 °C for 20 min, and 500 °C for 20 min. Generally, biochars produced at temperatures ≥400 °C did not inhibit root elongation, except for the material produced at 450 °C for 60 min (4.08 ± 23.34%). Biochars obtained at ≥300 °C showed a positive impact on seed germination (86.67 ± 18.48-100 ± 24.14%).

The Effect of Various Forms of Sulfur on Soil Organic Matter Fractions and Microorganisms in a Pot Experiment with Perennial Ryegrass (Lolium perenne L.)

This article focuses on the agronomic evaluation of the supplementation of mineral NPKMg fertilizers with elemental sulfur, magnesium, potassium, or ammonium sulfates in pot experiments with ryegrass growing in a sandy Arenosol with very low sulfur content. A benefit evaluation was carried out on the basis of biomass production, crop nutritional status, and changes in the content of soil organic matter fractions. Furthermore, the total number of bacteria, nitrogen-fixing bacteria, and fungi was estimated using the qPCR technique in soil samples after 60 days of ryegrass growth. The combined application of NPKMg and sulfur or sulfate fertilizers significantly increased the summary yield of three cuttings of fresh ryegrass biomass in the range of 32.3% to 82.7%. The application, especially in the form of sulfates, significantly decreased the content of free phenolic acids. Furthermore, compared to the control, i.e., soil with NPKMg applied alone, an increase in the content of glomalin-related proteins and a decrease in the amount of water-soluble organic carbon compounds were observed. Neither the number of DNA marker copy numbers of the total bacterial community nor the nitrogen-fixing bacteria were noticeably different. In turn, the total number of genetic markers for fungi was significantly higher in soils with potassium or ammonium sulfates compared to the control soil. The general results suggest that the application of sulfur fertilizers with NPKMg mineral fertilizer can benefit crops and support soil fertility due to the stabilization of aggregates and the decrease in water-soluble organic compounds.

Wastewater management in motor rest area - A review article

Due to the constantly developing road network, a large number of new Motor Rest Area facilities are being built. The aim of the work is a critical assessment of the current wastewater management in the MRA and the proposal of appropriate solutions capable of purifying wastewater. The analysis of the current state of the MRA facilities was carried out on the basis of maps, own observations and an assessment of interest in the subject recently by reviewing publication resources. For this purpose, analyzes of the frequency of occurrence of keywords describing the issue were used. The solutions used so far are ineffective. This is mainly due to the perception of wastewater produced in MRA facilities as domestic wastewater. This assumption leads to the selection of inappropriate solutions, which in the long run can lead to an ecological disaster by introducing untreated sewage into the environment. The authors point to the possibility of introducing a circular economy in these places to relieve their environmental impact. Since, wastewater generated in MRA facilities, due to its specificity, is very difficult to treat. They are characterized by uneven inflow, a lack of organic matter, a low C:N ratio and very high concentration of ammonium nitrogen. Conventional activated sludge methods cannot cope with this. The need for changes and the use of solutions suitable for the treatment of wastewater with a high content of ammonium nitrogen has been demonstrated. The authors presented solutions that have the potential to be used in MRA facilities. The application of the proposed solutions from that moment will undoubtedly change the impact of MRA facilities on the environment and solve the problem of wastewater management on a large scale. There is still a lack of research on this thematic scope, which is a challenge authors have taken up.

LED light use for the improvement of wastewater treatment in the hydroponic system

Effective removal of nitrogen and phosphorus from sewage before its discharge to the receiving water body is now a key task for scientists and technologists around the world. The widespread problem of eutrophication in the watercourses as well as in the seas and oceans obliges to take actions leading to more effective protection of water resources and implementation of sustainable development principles. One of the methods of increased wastewater treatment from nutrients is the use of a third stage of treatment with the use of macrophytes for the uptake of nitrogen and phosphorus. These systems, called hydroponic, under moderate climate conditions show little effectiveness due to the lack of sufficient light intensifying the growth of aquatic plants. The aim of this study was to evaluate the reduction of biogenic compounds concentrations in wastewater where additional lighting of plants was provided by the use of LED (Light Emitting Diodes), in two different conditions of experiment: with aeration and with carbon dioxide supplementation. Analyses show that the effectiveness of purification was higher in the wastewater supplemented with CO₂ and artificial lighting had no significant influence on the reduction of nitrogen forms concentrations. In wastewater with aeration, higher effectiveness of nitrogen removal was observed in the tank with artificial lighting. In both cases, aeration or CO₂ supplementation as well as artificial lighting or its lack, had no influence on total phosphorus and phosphates removal.

Changes in the granulometric composition of particles in wastewater flowing through a hydroponic lagoon used as the third stage in a wastewater treatment plant

Wastewater treatment in semi-natural systems, such as a hydroponic lagoon operating as the third stage of purification, is becoming more and more popular because of the efficiency of nutrient removal. Very often treatment processes in hydroponic ditches are supported by algal growth, which can cause an increase in the concentration of total suspended solids in the outflow from the wastewater treatment plant. The aim of this study was to analyse changes in the granulometric composition of particles in the hydroponic lagoon operating as the third stage of wastewater purification in a municipal wastewater treatment plant (WWTP) in Poland. Measurements of the particle sizes were made with the use of the laser diffraction method. The results showed that the size of the particles in the hydroponic lagoon varied from 0.01 to 1000 μm. Analyses of the average diameters D(3.2) and D(4.3) showed that particles have low reactivity but good sedimentation properties and their fractal dimensions are usually higher than 2.0, which indicated that they had well-developed surfaces. Most of the particles flowing out of the WWTP were probably algae or particles that could adsorb other pollutants onto their surfaces. The use of laser granulometry for particle identification might be useful in characterizing the total suspended solids as well as helping to develop cheaper and more efficient methods for its removal.

Analysis of the Algae Growth Dynamics in the Hydroponic System with LEDs Nighttime Lighting Using the Laser Granulometry Method

The latest research focused on the analysis of algal growth and the dynamics of their growth use the laser diffraction technique, enabling determination of the volume fraction of suspended particles with specific diameters in aqueous solution as well as their fractal dimensions. This study focuses on the possibility of using a laser granulometer to assess the growth dynamics of algae growing in treated wastewater in a hydroponic system, supported by artificial lighting with the use of light-emitting diodes (LEDs). On the basis of the measurements, the fractal dimension (Df) of algae was determined. An attempt was made to apply the modified Avrami equation describing the crystallization process for the analysis of algae growth dynamics in wastewater. Presented results show that the fractal dimension of suspended matter, largely created by algae, in the case of additional lighting of the hydroponic system at night, takes lower values (Df ~ 1.0) than in sewage without additional light source (Df ~ 2.0). In each measurement series, the fractal dimension of particles in the tank with lighting in the end of the experiment was about 33-43% lower than in the tank without LEDs. The analysis of changes in particle diameters calculated on the basis of Avrami equation largely corresponds with the stages of algae growth. During the measurement series with lower air temperatures, the growth of algae in the tank with additional light was faster than in the tank without LEDs. The obtained information can be the basis for determining the effective method of removing algae from wastewater treated in the hydroponic system, before they are discharged to the receiver in order to prevent the outflow of increased concentrations of total suspended solids.

Influence of Insolation on the Efficiency of NO3 Removal from Wastewater Treated in the Hydroponic System

The use of plants and natural processes for wastewater treatment is an issue that arouses interest among technologists and scientists around the world. The aim of the article was to analyze the influence of the air temperature and insolation on the removal of nitrate nitrogen from the wastewater treated in the hydroponic system, under greenhouse conditions. Samples of sewage for its quality tests were taken from a wastewater treatment plant (WWTP) located in the southwestern part of Poland. Data regarding daily sunshine duration and average daily air temperature values in selected periods of 2013-2016 come from a meteorological station located 30 km from WWTP. The conducted research and analyses of the results clearly indicate that under moderate climate conditions, the amount of solar radiation reaching the Earth's surface is insufficient to ensure the year-round, effective wastewater treatment process in the hydroponic system. In the case of air temperature, no correlation was found between the tested parameters, which indicates the lack of temperature influence on the efficiency of NO₃ removal from the wastewater by macrophytes growing in the lagoon.

Analysis of Granulometric Composition of Algal Suspensions in Wastewater Treated with Hydroponic Method

The aim of the study was to determine the changes in suspension particle size identified in biologically treated wastewater, which was then treated in hydroponic system with use of engineering lighting by the light-emitting diodes (LED). The study was subjected to wastewater purified under laboratory conditions, in a hydroponic system using the effect of macrophytes Pistia stratiotes and growing algae. Measurement of particle size was made using a laser granulometer. Analysis of the results showed that the additional lighting of the hydroponic system with LED can significantly influence the ability of the suspension particles to agglomerate and, consequently, determine their sedimentation properties. In hydroponic system supported by additional lighting, more particles were observed with equivalent diameter D(3.2) smaller than 10 μm than those in the tank without additional lighting, indicating a higher reactivity of the particles. Determining the size of equivalent diameters D(4.3) allowed us to observe that in hydroponic system, particles of relatively small size predominate, which negatively affects the sedimentation process of the suspensions. Determination of particle size of suspensions consisting mainly of algae and the dynamics of their changes are the basis for specification of an effective method of removing particles from the system to protect the receiver from excessive suspension concentrations.