Initial Nitrogen Concentration Research Articles

Effects of carbon sources on the removal of ammonium, nitrite and nitrate nitrogen by the red yeast Sporidiobolus pararoseus Y1

Heterotrophic nitrification and aerobic denitrification (HN-AD), which is primarily performed by bacteria rather than fungi, is an attractive approach for nitrogen removal. In this study, a red yeast, Sporidiobolus pararoseus Y1, was isolated and shown to exhibit optimal growth and nitrogen removal efficiency on glucose, followed by citrate, sucrose, acetate and starch. The nitrogen removal efficiency increased with increasing initial concentrations of NH4+-N, NO2−-N and NO3−-N from 14 to 140 mg·L-1. At an initial nitrogen concentration of 140 mg·L-1, the maximum removal efficiencies of NH4+-N, NO2−-N and NO3−-N were 98.67%, 97.13% and 83.51% after 72 h incubation, while those of corresponding total nitrogen were 88.89%, 81.31% and 70.18%, respectively. The nitrification (amoA) and denitrification genes (nirK and napA) were amplified from Y1. These results suggest that yeast are also capable of HN-AD, which can be used to remove nitrogen in wastewater systems.

Modelling of <em>S. cerevisiae</em> and <em>T. delbrueckii</em> pure culture fermentation in synthetic media using a compartmental nitrogen model

Aim: The objective of the present work is to propose a model describing the evolution of the pure culture fermentation of two oenological yeasts: S. cerevisiae and T. delbrueckii.Methods and results: For both yeasts, pure culture fermentation was performed in a synthetic medium with different initial concentrations of yeast available nitrogen. The datasets obtained from those experiments were used to identify the parameters of the proposed model.Conclusions: The developed comprehensive model of wine-making fermentation is based on the partition of assimilated nitrogen between the constitutive and the storage compartments. It efficiently describes the evolution of S. cerevisiae and T. delbrueckii pure cultures. This mass-balance model provides a stoichiometric approach in biomass production, unlike nitrogen backboned models used in winemaking. Moreover, it gives an estimation of non-accessed data such as nitrogen partition between vacuole and cytosol during T. delbrueckii fermentation.Significance and impact of the study: The developed model is robust enough to precisely describe the fermentation evolution of two pure culture yeasts and therefore has future potential for modelling mixed culture fermentations of S. cerevisiae and T. delbrueckii.

Chlorine mediated indirect electro-oxidation of ammonia using non-active PbO2 anode: Influencing parameters and mechanism identification

Removal of ammonia-nitrogen from wastewater has gained considerable attention in recent years to reduce the critical problems arising in the water bodies receiving ammonia containing wastewater. Eutrophication and formation of odors due to wastewater discharging, the formation of undesirable by-products during the disinfection process can be significantly reduced using various treatment technologies. Although biological processes are mainly implemented to reduce ammonia-nitrogen concentration, several studies demonstrated electro-oxidation process as a potential alternative for ammonia-nitrogen removal. Among the non-active anodes, the majorly studied anode for chlorine mediated ammonia oxidation is boron-doped diamond anode. In this study, a non-active but comparatively low-cost graphite/PbO2 anode has been proposed for removing ammonia-nitrogen from wastewater. The study describes the effects of three influencing factors; current intensity, initial Cl− and NH3-N concentration on the oxidation efficiency of ammonia using graphite/PbO2 anode. The ammonia removal efficiency was found to be dependent on all the three parameters selected. The NH3-N removal efficiency of 96.5 ± 0.4% was achieved after 120 min of electro-oxidation of 100 mg L−1 NH3-N and 900 mg L−1Cl− containing solution at a current intensity of 0.3 A. Nitrate ion, and nitrogen gas were found as the stable end-products of the ammonia removal process. The formation of desirable end-product, N2, increased from 11.6% to 28.9% with increase in Cl− concentration from 300 to 1500 mg L−1. The steady-state concentrations of chloramine indicate formation of chloramine as an intermediate step of ammonia-nitrogen removal. The total chloramine concentration was <2.5% of the initial nitrogen content throughout the reaction.

Techno-economic evaluation of ammonia recovery from biogas slurry by vacuum membrane distillation without pH adjustment

A techno-economic evaluation of ammonia recovery from biogas slurry without pH adjustment by vacuum membrane distillation was performed in this study. After experimentally exploring the effects of key operation parameters on the ammonia separation performance, we conducted the orthogonal experiments to obtain the optimal operation conditions. The results indicated that the maximum ammonia separation factor can reach up to 8.05 under the optimal conditions, implying the technical feasibility of ammonia recovery from biogas slurry without pH adjustment by vacuum membrane distillation. We also investigated the economic evaluation of this ammonia recovery system for NH4HCO3 production considering different pH adjustment methods and heat sources. When the total ammonia nitrogen content is 2 g-N/L and heat is supplied by natural gas combustion, the profit of this ammonia recovery system is about $0.4/m3-biogas slurry for the case without pH adjustment, while the profit decreases greatly to about $-2.06/m3-biogas slurry for the case using NaOH to increase pH value and $-0.06/m3-biogas slurry for CaO addition case. Sensitivity analysis illustrated that the membrane lifetime is the most significant impact factor at a fixed initial total ammonia nitrogen content of biogas slurry. With an increase of initial total ammonia nitrogen content of biogas slurry from 0.5 to 4.0 g-N/L, the profit increases gigantically from $-0.71/m3-biogas slurry to $1.88/m3-biogas slurry. The study can provide a green and sustainable nitrogen fertilizer production process.

Rapid changes in the chemical composition of degrading ectomycorrhizal fungal necromass

Abstract Characterizing the chemical changes in fungal necromass as it degrades, particularly over short time intervals (days to weeks), is critical to clearly understanding how this organic matter source contributes to various belowground carbon and nutrient pools. Using a range of chemical analyses, we assessed the degradation of four types of ectomycorrhizal fungal necromass from three species differing in biochemical composition. Samples were buried in a forest in Minnesota, USA and harvested at eight time points over a 90-day incubation period (1, 2, 4, 7, 14, 28, 60, 90 days). Three of the necromass types lost greater than 50% of their initial mass in the first seven days, but mass loss plateaued for all four types at later harvests, and after 90 days, none of the samples were completely degraded. Relative to undegraded necromass, degraded necromass consistently contained a lower relative abundance of aliphatic compounds and a higher relative abundance of carbohydrates, sterols, and aromatic compounds. For three of the four necromass types, nitrogen content was lower after 90 days of degradation and FTIR spectra revealed distinct peaks broadening from day 0 to day 90. While melanin content significantly slowed degradation within species, differences in degradation rates across species were more closely aligned with initial nitrogen content. Collectively, our results indicate that the rapid mass loss of dead fungal mycelium is accompanied by a wide range of changes in necromass chemistry, likely contributing to both short-term soil nutrient and longer-term carbon pools.

Potential of immobilized Chlorella minutissima for the production of biomass, proteins, carotenoids and fatty acids

Abstract This work investigated the potential of Chlorella minutissima immobilized in alginate beads for biomass and bioactive compounds production. The effects of nitrogen concentration in the culture medium (48 to 96 mg L-1 N–NO3) and the nitrogen addition profile during fed-batch culture were evaluated. In batch cultures, the initial nitrogen concentration of 96 mg L-1 N–NO3 produced the highest chlorophyll and protein contents in biomass, about 2.8 and 1.5-fold higher than the control (48 mg L-1 N–NO3), respectively. The biomass concentration (1.65 ± 0.01 g L-1) and carotenoid content (11.0 ± 0.8 mg g-1) were 21.3% and 32.6% higher than the control (48 mg L-1 N–NO3), but similar to the other nitrogen concentrations tested (64 and 80 mg L-1 N–NO3). Fed-batch cultures were performed in order to optimize the productivity of immobilized C. minutissima. The fed-batch culture with three additions of 96 mg L-1 of N–NO3 resulted in the highest biomass concentration (2.13 ± 0.02 g L-1) and an increase in chlorophylls (1.7-fold), carotenoids (1.3-fold) and proteins (1.6-fold) content in biomass compared to batch culture. The contents of all-trans-lutein and polyunsaturated fatty acids were 5.31 ± 0.46 mg g-1 (dry cell weight) and 52.0 ± 0.9% of total fatty acids, respectively, similar or higher than free cell cultures. The culture of immobilized C. minutissima cells showed to be a promising technique towards decreasing microalgae production costs. Through fed-batch cultures, it was possible to increase the production of biomass and compounds of biotechnological interest.

Inhibition of Alga Contamination in Open-Culture Under Silicon Stress

Alga contamination was a major problem in microalgae open cultivation. The objective of this study was to estimate the effect of silicon on microalgae growth by mixed-culture experiments with four different microalgae. The results showed that under the osmotic pressure caused by high concentration of Na2SiO3, Navicula sp. N6 had a competition advantage of absorbing nutrient compared with the other three microalgae. The impacts (initial pH, nitrogen content, and silicon content) on cell growth and lipid accumulation were investigated by response surface analysis and the biomass and lipid content increased from 1.01 g/L and 10.98% to 1.33 g/L and 20.04% under the optimal conditions, with lipid yield raised from 110.90 mg/L to 266.53 mg/L. Comparison on the growth under optimum and silicon deficiency condition indicated that silicon played an important role on the growth of Navicula sp. N6 and algal contamination in diatom open scale cultivation could be solved by regulating the sodium silicate concentration.

Effectiveness of Scenedesmus sp. Biomass Grow and Nutrients Removal from Liquid Phase of Digestates

One of the most important factors in determining the profitable production of microalgae biomass is the use of a cost effective growth medium that is rich in nutrients. The objective of the study was to determine the possibility of using digestates from anaerobic digestion of different feedstock mixtures as the media for Scenedesmus sp. cultivation. A different liquid digestate composition was obtained in terms of organic compounds, phosphorus, and nitrogen concentrations, depending on the substrates used in the anaerobic digestion. It was found that the highest biomass production was obtained when using digestate from anaerobic digestion of the feedstock mainly composed of microalgae biomass, which was characterized by low organic compounds concentration. In this case, the average biomass concentration reached 2382 mg total solids/L. A lower Scenedesmus sp. biomass yield was obtained using digestate from anaerobic digester processing feedstock based on maize silage and cattle menure. In the variants of the study, it was also found that the increase in the initial concentration of ammonia nitrogen in the growth medium up to 160 mg/L significantly reduced the growth of Scenedesmus sp. The results indicated the possibility of a high ammonia nitrogen and orthophosphates removal from anaerobic digestates by Scenedesmus sp. microalgae. Phosphorus concentration in the cultivation medium is a limiting factor for the growth of Scenedesmus sp., thus phosphorus supplementation should be considered when using liquid digestate as the culture medium. The optimization model indicated that the volume of liquid digestate that was used for preparing the cultivation medium, the initial concentration of organic compounds, and the initial concentration of ammonia nitrogen had a significant impact on the production of Scenedesmus sp. biomass.

Comparative analysis of factors affecting differences in the concentrations of gaseous anthropogenic emissions from coal and slurry fuel combustion

The paper presents the results of the experimental research performed for a comparative analysis of factors that influence the concentrations of the main gaseous anthropogenic emissions from coal and waste-based slurry fuel combustion. We focus on controlling the NOx and SO2 concentrations. We have researched for the first time a group of mechanisms and factors, influencing the formation of anthropogenic emissions from burning waste as part of wet multi-component slurry fuels. The experiments were conducted with coals of different grades, coal processing waste, water-containing slurries, as well as extra additives of biomass and waste. We show how much the NOx and SO2 concentrations are affected by a wide group of factors and processes: temperature in the chamber, vaporization, initial content of sulfur and nitrogen in the fuel mixture, specialized additives with different concentrations and in different combinations, as well as specific chemical reactions in a limited range of temperatures. The experimental results show that the initial content of nitrogen in the slurry and the catalytic processes of nitrogen oxide reduction to free N2 have a dominant influence on NOx emissions due to free hydrogen radicals and interaction of additives with the components (e.g., with Fe2O3). SO2 concentrations are decisively influenced by the content of sulfur in the slurry, as well as the chemical interactions of amphoteric and active metals with sulfur oxides. Combined employment of a group of factors under study can provide a reduction of NOx and SO2 by up to 80% as compared to coal combustion conditions.

Synthesis of Two Kinds of Mesoporous Diatomite by Microwave Assisted Sol-Gel Method and Its Adsorption of Ammonia Nitrogen in Wastewater

The microwave-assisted sol-gel method was used to synthesize mesoporous diatoms (DM) and magnetic mesoporous diatoms (MDM), and used as adsorbent to remove ammonia nitrogen from water. The effect of reaction time, solution pH, and initial concentration of ammonia nitrogen on adsorption was studied, and the adsorption Kinetics and thermodynamic characteristics of DM and MDM were analyzed. The results showed that at 25 °C, when the dosage of DM and MDM was 4 g/L, the initial concentration of ammonia nitrogen in the solution was 50 mg/L, the value of pH was 7, and the adsorption time was 30 min, the adsorption of ammonia nitrogen in solution by DM and MDM was 6.95 and 7.79 mg/g, respectively. DM and MDM had good adsorption effect on ammonia nitrogen, and the adsorption process complied with the Pseudo-second-order kinetics equation and Freundlich isothermal adsorption model.

Vertical In Vessel Composter for Stabilization of Market Vegetable Waste

Composting can be one of the solutions to tackle the issue of handling solid waste. In the present research work, a bench-scale vertical in-vessel aerobic composter was designed to stabilize the Devaraja market vegetable waste, Mysore using horse dung and plantain leaves as seeding material and bulking agent respectively. On average, Devaraja market generate 4.8-5.6 ton per day. Mix proportion of organic waste, bulking and seeding materials fed into composter was in the ratio of 5: 1: 0.5. Initial and variation in physico-chemical characteristics of waste were monitored during the composting period. The initial concentration of total nitrogen, phosphorous, total organic carbon and C/N ratio which was found to be 1.67%, 0.78%, 1.93%, 43.5% and 26 showed a variation of 2.4%, 1.1%, 2% 29% and 15 respectively at the end of 21 days of composting.

Heuristic Optimization of Culture Conditions for Stimulating Hyper-Accumulation of Biomass and Lipid in Golenkinia SDEC-16

Overproduction of biomass and hyper-accumulation of lipids endow microalgae with promising characteristics to realize the cost-effective potential of advanced bioenergy. This study sought to heuristically optimize the culture conditions on a rarely reported Golenkinia sp. The results indicate that Golenkinia SDEC-16 can withstand the strong light intensity and grow in a modified BG11 medium. The optimal culture conditions for the favorable tradeoff between biomass and lipid accumulation were suggested as follows, 25,000 lux of light intensity, 9 mM of initial nitrogen concentration, and 20 mM of initial sodium chloride concentration. Under these conditions, the biomass concentration and productivity reached 6.65 g/L and 545 mg/L/d, and the synchronous lipid content and productivity reached 54.38% and 296.39 mg/L/d. Hypersalinity significantly promoted lipid contents at the cost of biomass and resulted in an increase of cell size but loss of spines of Golenkinia SDEC-16. The results shed new light on optimizing biomass and lipid productivity.

Two directions of regeneration of post-windthrow pine stands depend on the composition of the undergrowth and the soil environment

Alongside fires, windthrows are among the strongest forest disturbances, which is why research on the regeneration of windthrown forests is so important for silviculture. While there have been many studies devoted to the regeneration of windthrown boreal spruce forests, few have dealt with the regeneration of Scots pine forests in the temperate zone.In Pisz Forest (northern Poland), the State Forests administration left 475.6 ha of pine stands disturbed by windthrow for research on spontaneous ecosystem recovery, leaving all broken trees untouched. For the 11-year study (beginning in 2008, six years after the windthrow, when saplings became more abundant), 10 × 10 m research plots were established in pine stands with different classes of severity of windthrow disturbance: severely disturbed stands (canopy cover up to 30%), moderately disturbed stands (canopy cover of 40–60%) and the least disturbed stands (canopy cover of 70–90%). Each year all saplings on the plots were recorded, with measurements of their height, diameter at breast height, and changes in the percentage cover of forest floor vegetation and its species composition. Selected environmental variables were measured as well. Density of pine saplings in the severely disturbed stands was lower than in the moderately and least disturbed stands, while the density of birch saplings was higher in the moderately disturbed stands than in the least disturbed stands. Moss P. schreberi particularly favored spontaneous regeneration of pine saplings, while the nitrophilous grass D. flexuosa, overgrowing entire surfaces, impeded it. Soil cover by a litter layer alone also significantly hampered the emergence of tree saplings.An elevated content of nitrogen in the soil was conducive to rapid coverage of the area by D. flexuosa, while limiting cover by moss P. schreberi. Moss P. schreberi and shrubs V. vitis-idaea preferred soil with a high respiration rate, while grass D. flexuosa avoided it. Two directions of spontaneous regeneration of windthrown stands were shown, depending on cover by grass or mosses and on the initial content of nitrogen in the soil, which provided the basis for indicating two different forest management strategies in windthrown pine forests.

Minimum tillage and residue retention increase soil microbial population size and diversity: Implications for conservation tillage.

A global meta-analysis was conducted to evaluate the effect of conservation tillage practices on soil microbial population size [based on microbial count and phospholipid fatty acid (PLFA) measurements], diversity (Shannon index), and microbial community structure. Both no-tillage (NT) and NT plus residue retention (NTS) increased soil microbial count as compared with conventional tillage (CT). Bacteria, fungi, and actinomycete counts were 3%, 18%, and 28%, respectively, higher under the NTS treatment relative to the NT treatment, and 38%, 41%, and 28%, respectively, higher in the CT plus residue retention (CTS) treatment than in the CT treatment. No-tillage, as compared to CT, increased total PLFAs by 11%. The concentration of fungal PLFAs was increased by 17% by NT as compared to CT, but was decreased by 52% by NTS as compared to NT. The actinomycete PLFA concentration was decreased by reduced tillage and CTS, compared to CT. Compared with CT, NT increased the Shannon index of the total microbial and bacterial communities by 4% and 6%, respectively. The bacterial count was negatively associated with mean annual precipitation (275-1624mm) and experimental duration (1-35years) and positively associated with initial total soil nitrogen concentration. Overall, relative to CT, minimum tillage alone increased soil microbial count, fungal biomass, and bacterial diversity; residue retention alone increased soil microbial count and fungal diversity, and decreased the biomass of actinomycetes; combining minimum tillage and residue retention increased soil microbial count and fungal diversity. We conclude that the response to minimum tillage and residue retention was consistently positive for soil microbial count but was context dependent for microbial biomass, diversity, and community structure.

Performance analysis of inert gas systems in main distribution board room using fire dynamics simulation

This study focused on the fire-extinguishing performance of inert gas in main distribution board room using fire dynamics simulator. The study included 4 types of inert gas: Nitrogen, Argon, Argonite and Inergen. The simulation was done in a 1 meters wide x 2.1 meters height x 1 meters deep main distribution board. In simulation, according to each type of inert gas, 3405.0 kW/m2 heat release rate of electrical wires with ramp-up time at 492.0 second using concentration of inert gases based on NFPA 2001 standard. With initial concentration of Nitrogen at 41.9%, Argon 52.9%, Argonite 42.7% and Inergen 38.5% and also simulated the incidents when increased safety factor of Class C fire to 50% and 100% respectively in all 4 experimental gases which divided into 12 cases.The results showed that different types of inert gases did not affect the fire-extinguishing performance caused by the same fuel in the same environment. And the increasing of safety factor of Class C fire by 50% and 100% respectively in all 4 types of inert gas did not improve their fire-extinguishing performance.

Kinetic study on nitrification of ammonium nitrogen-enriched synthetic wastewater using activated sludge.

Nitrification of ammonium nitrogen (NH4 +-N)-bearing synthetic wastewater was performed in a batch-activated sludge reactor by varying the initial ammonium nitrogen concentration up to 400 mg/L at a pH of 8.1 ± 0.2 and temperature of 36 ± 2 °C for developing the process kinetics using acclimatised biomass. Maximum ammonium nitrogen removal efficiency of 98.3% was achieved with initial ammonium nitrogen and mixed liquor suspended solids concentration of 235 mg/L and 2,180 mg/L, respectively, at 48 h batch period. Based on the experimental results, kinetic constants for ammonia nitrogen removal following Monod's approach were obtained as maximum substrate removal rate coefficient = 0.057 per day, yield coefficient = 0.336 mg volatile suspended solids/mg ammonium nitrogen, half velocity constant = 12.95 mg NH4 +-N/L and endogenous decay constant = 0.02 per day. Nitrification is a consecutive reaction with ammonium oxidation as the first step followed by nitrite oxidation. The overall rate of nitrite and nitrate formation was observed to be 1.44 per day and 0.34 per day, respectively.

Heterotrophic nitrogen removal by a newly-isolated microorganism, Oligella sp. XS68

A new bacterium capable of heterotrophic nitrogen removal was isolated and identified as Oligella sp. XS68. The strain exhibited efficient heterotrophic nitrogen removal capabilities, with a low accumulation of nitrification products. Single-factor experiments indicated that efficient nitrogen removal and growth of the strain XS68 occurred with sodium succinate as the carbon source, C/N ratio 15, pH 6.0?9.0, temperature 30?37 ?C, and shaking speed 160?200 rpm. The removal efficiency of ammonium nitrogen could achieve 98 % within 96 h when the initial nitrogen concentration was 421.3 mg L-1. These findings demonstrate that XS68 is a promising candidate for nitrogen removal in wastewater treatments.

Study on greenhouse soil nitrogen absorption and soil layer transport of different summer catch crops with different planting density in North China

In order to improve the utilization rate of nitrogen fertilizer and reduce the environmental pollution risk of the nitrogen accumulation in the vegetable field, this study was carried out in the summer leisure period of the greenhouse vegetable production. This experiment designed different planting density treatments in 2017 and 2018, i.e. for catch waxy corn, 3300 plants/667m2 (WCD1), 5000 plants/667m2 (WCD2), 6600 plants/667m2 (WCD3), for forage sweet sorghum, 4500 plants /667m2 (FSS4), 7000 plants/667m2 (FSS5), 9000 plants/667m2 (FSS6) in 2017; and for catch waxy corn, 4500 plants/667m2 (WCDI), 7000 plants/667m2 (WCDII), 9000 plants/667m2(WCDIII), for forage sweet sorghum, 7000 plants/667m2 (FSSIV), 10000 plants/667m2 (FSSV), 14000 plants/667m2 (FSSVI) in 2018. The results showed that the biomass and nitrogen absorption of the two catch crops began to improve and then decreased with the increase of planting density. The nitrogen absorption amount of the catch waxy corn and forage sweet sorghum was 22.36~28.68 kg/667m2,21.67~24.39 kg/667m2, respectively. Different planting density of catch waxy corn and forage sweet sorghum could significantly reduce the total nitrogen content of 0~30cm soil layer and the nitrate nitrogen content of 0~90cm soil layer, for catch waxy corn and forage sweet sorghum, the reduction rate of total nitrogen content in 0~30cm soil layer was 9.6%~27.0%, 5.7%~23.5%, the reduction rate of nitrate nitrogen content reached 50.0%~90.8%, 80.1%~96.4%, respectively, which effectively controlled the nitrate nitrogen leaching to soil deep layer. Planting catch crops could increase soil urease activity, regulate soil nitrogen transformation. Compared with other treatments, WCDII and FSSV treatment can reduce the initial urease activity and soil nitrate nitrogen content of next crops, which is consistent with the nutrient requirements of broccoli in the early stage of growth. These catch crops planting could reduce the nitrogen environmental risk in the greenhouse soil. Finally, the study proposed that the suitable planting density of catch waxy corn and forage sweet sorghum planted was 6600~7000 plants/667m2, and 9000~10000 plants/667m2, respectively, in the greenhouse summer leisure period. It is more advantageous to improve soil nitrogen absorption and reduce soil nitrogen environmental risks for catch waxy corn.

Bioremediation of Heavy Metal Contaminated Soils Originated from Iron Ore Mine by Bio-augmentation with Native Cyanobacteria

The soil in the Sangan iron-mining region in the east of Iran is contaminated with a high concentration of heavy metals, especially iron. The release of these pollutants into environment results in the transfer and accumulation of iron through the food chains, hence a reasonable solution is required to restore it. Bioaugmentation is an environmental friendly option to reduce the hazard effects of heavy metal in the contaminated soil. In this study, the consortia of two indigenous cyanobacteria isolated from soil of Sangan iron mining and used to bioremediate soil contaminated with iron, chromium, copper, lead, and nickel. The experiments were carried out by three treatment methods, including control soil, surface soil sprayed with cyanobacteria, and soil mixed with cyanobacteria for six months under laboratory condition. The scanning electron microscope showed the development of a network of filaments of the inoculated cyanobacteria (Oscillatoria sp. and Leptolyngbya sp.) with soil particles in both treatments. Bio-augmentation of the soil increased initial nitrogen content from 406 mg/kg in control to 664 mg/kg in soil mixed with cyanobacteria and 710 mg/kg in soil sprayed with cyanobacteria. Cyanobacteria inoculation decreased the available concentration of lead and nickel. The non-available heavy metal of soil in sample sprayed with cyanobacteria was in decreasing order: Cr > Fe > Ni > As > Pb > Cu. The maximum metal removal efficiency was 32%. In soil mixed with cyanobacteria increased in the root and hypocotyl lengths of radish and lettuce was observed compared to that in the control soil, indicated in the improvement of soil quality after bioremediation.

Potential treatment of leachate by Hermetia illucens (Diptera, Stratyomyidae) larvae: Performance under different feeding conditions.

In this study, the ability of H. illucens larvae (black soldier fly (BSF)) to metabolise different semisolid biowastes (e.g. kitchen waste, animal manure) has been applied to the treatment of landfill leachate. A testing programme has been developed by mixing leachate with three different solid supports: wheat bran, a biodegradable nutrient substrate, brewers' spent grain, a biodegradable nutrient residue from the brewery industry and sawdust, a low biodegradable residue from the wood industry. Larvae growth rate was monitored in terms of weight variation, mortality and time to reach the prepupal stage. Prepupal biomass composition was analysed in terms of crude protein, lipids and fatty acids. Substrates were monitored at the beginning and the end of tests for total solids (TS), total organic carbon (TOC), total Kjeldahl nitrogen (TKN), ammonia and (whenever significant) the 7-day Respirometric Index (RI7). The best performance was observed with wheat bran and brewers' spent grain, achieving an average larval weight ranging from 155.1 to 226.1 mg (w/w) with prepupation of more than 80% over 21 days. The initial TS, TOC and nitrogen content in feeding substrates had been metabolised (gasified and accumulated in prepupal biomass) by approximately 55%, 60% and 48%, respectively. Dry mass characterisation displayed a significant content of fats and proteins. The analysis demonstrated the suitability of BSF prepupal biomass for the production of biodiesel; however, the potential use of proteins as an animal feed needs further studies for assessing the presence of contaminants.