Nitrogenous Substances Research Articles

Ecological problems of the river Novaya (St. Petersburg) and ways to solve them

Main sources of pollution of the river Novaya, one of the most ecologically unfavorable water bodies in St. Petersburg, have been revealed on the basis of hydrological, hydrochemical and geochemical data. The river lost natural water supply and its length decreased by 4 times after the runoff from the upper part of catchment was redirected to the river Dudergofka during the construction of the Pulkovo Airport several decades ago. Currently, the river is a drainage system of agricultural territory, supplying a system of six connected ponds at urban area. The main ecological problem of the aquatic system under study has been found to be nutrient and organic pollution. Main reason of pollution is intensive agricultural activity at the catchment area. As a result, a huge amount of phosphorus, nitrogen and organic substances enters the hydrographic network. Low flow rate of the water system makes worse the development of negative processes in the ecosystem. The main polluter is a livestock enterprise located in the upper part of the catchment area. It discharges wastewater into the drainage system in the catchment area and manures agricultural fields directly adjacent to the riverbed. In accordance with the evaluation criteria of the degree of surface waters chemical pollution, approved by the Ministry of Natural Resources of the Russian Federation, the situation is assessed as extreme in the aquatic system, and at some sites - as a zone of ecological disaster by a number of parameters. No contamination of water and bottom sediments, as well as soils in the catchment area with priority organic pollutants previously entering from the airport territory was detected. Nutrient loading on the aquatic system of the catchment area from the agricultural enterprise has been calculated. It has been assessed that the use of the best available technologies for agricultural activity could reduce the phosphorus load by 9 % and the nitrogen load by 28 %. Currently, the calculated concentration of total phosphorus in the drainage system in the catchment area is 4 times higher than the hyper eutrophic state limit. An improvement in the ecological situation can be achieved by optimizing agricultural activity in the catchment area, periodical removal of some nutrients and organic substances by mowing macrophytes in the swampy floodplain area, establishing a coastal protective zone and increasing the flow rate as a result of the return of runoff from the upper part of the river catchment to the former course

Nutritional status, production and fruit quality of west indian cherry fertigated with nitrogen and humic substance

Abstract Information on humic substances (HS) associated with nitrogen fertilization in West Indian cherry is scarce in the literature. The use of soil conditioners, such as HS, can increase the efficiency in the absorption of nutrients, especially N. Therefore, the present study aimed to evaluate, in two production cycles, the fruit quality, yield and nutritional status of West Indian cherry as a function of fertigation with nitrogen (N) and HS in Petrolina-PE, Brazil. The experimental design was in split plots, with treatments distributed in 5 x 2 strips, referring to N doses (50, 75, 100, 125 and 150% of the recommended dose) and HS application (without and with), respectively, with 4 replicates and 3 plants per plot. The N source used was urea (45% N) and the HS source used was the commercial product KS100 (Omnia®), from leonardite, monthly applied at dose of 6 g plant-1. Production, yield, indices of chlorophyll a, chlorophyll b and total chlorophyll, and leaf contents of N, P, K, Na, Ca, Mg, Fe, Mn and Zn were determined. Fruits were evaluated for: pH, vitamin C, soluble solids (SS), titratable acidity (TA) and SS/TA ratio. Except for leaf N content, which increased linearly with the applied doses, the leaf contents of nutrients, production and yield of West Indian cherry showed a stochastic pattern as a function of the increase in N availability and HS application. West Indian cherry plants cultivated and fertilized according to the recommendation for the crop did not respond to the evaluated treatments. Application of humic substances and N doses did not alter the post-harvest quality of West Indian cherry fruits.

Conservation and quality of grumatã (Prochilodus lineatus) fillets after different depuration periods and frozen storage

Abstract The aim of this study was to evaluate the physicochemical, microbiological, sensory and meat quality characteristics of grumatã fillets after different depuration (0, 48, 72 and 96 h) periods and frozen storage (0, 2, 4 and 6 months). The fish collected in a dam were distributed in tanks at a density of 3.8 kg m3 -1. After depuration periods, all fish were filleted and the fillet samples stored (−18 °C) until analyses. Lower fat content was found in fish submitted to depuration for 48 and 96 h compared to the non-depurated and those depurated for 72 h. Muscle protein was preserved in 48 and 96 h treatments. Coagulase-positive Staphylococcus, coliforms at 45 °C and Salmonella spp. were not observed in the fillets, but aerobic mesophilic microorganisms and coliforms at 35 ºC were detected. Sensory analysis showed no significant differences in appearance, colour, texture, flavour attributes and overall acceptance. During frozen storage, pH, total volatile basic nitrogen (TVB-N), peroxide and thiobarbituric acid reactive substance (TBARS) values were evaluated in fillet samples every two months. The pH values increased up to four months of storage. The TVB-N values ranged in fillets from fish depurated for 48 and 96 h. Peroxide values increased from the fourth month of storage, with the highest values observed in the sixth month. For TBARS values, increased values were found in fillets from non-depurated fish and lower values in other depuration periods. Thus, depuration is more efficient in maintaining the quality of grumatã fillets in frozen storage.

Piperine synergistically enhances the effect of temozolomide against temozolomide-resistant human glioma cell lines

ABSTRACT Temozolomide (TMZ) is an alkylating chemotherapy agent used in the clinical treatment of glioblastoma multiforme (GBM) patients. Piperine (PIP) is a naturally occurring pungent nitrogenous substance present in the fruits of peppers. We investigated the anti-cancer efficacies of PIP alone and in combination with TMZ in GBM cellsusingparameters such as cell proliferation, cellular apoptosis,caspase-8/-9/-3 activities, cell cycle kinetics, wound-healing ability, and loss of mitochondrial membrane potential (MMP). Treatment with PIP and alow concentration of PIP-TMZ, inhibited cell growth, similar to TMZ.PIP-TMZ promoted apoptosis by activation of caspase-8/-9/-3, MMP loss, and inhibition of in vitro wound-healing motility. Reverse transcription polymerase chain reaction analysis showed significant inhibition of Cyclin-dependent kinases (CDK)4/6−cyclin D and CDK2−cyclin-E expression upon treatment with a low concentration PIP-TMZ, suggesting an S to G1 arrest. Our findings provide insight into the apoptotic potential of the combination of a low concentration of PIP-TMZ, though further in vivo study will be needed for its validation.

Koncentracija uree u kozjem mlijeku: važnost određivanja i čimbenici varijabilnosti

The optimal concentration of urea in cow's milk is known and is often used to assess the balance of energy and protein in diets. While in goat (and sheep) milk it is not controled nor defined. Main determinants of urea formation in milk are the amount of crude protein intake and the ratio betwwen protein and energy proportion in diet. Goat diet with excessive amount of crude protein and energy unbalanced diet cause the excess of nitrogenous substances in rumen along with release of ammonia and rise in concentration of urea in blood and milk, which adversely affects the production, milk coagulation propreties, environmental pollution and reproductive capabilities of goats. However, besides diet, there are other factors that influence milk urea concentration: breed, stage of lactation, parity, season, body mass, litter size, production and chemical composition of milk. Numerous studies conducted on cow milk included the influence of sources of variability listed above, while there are only few studies available for goat milk due to its less economic importance, seasonal polyesterity and different way of breeding and keeping goats. The aim of this paper is to comparatively and critically combine the previous research results on the importance of determining the milk urea concentration as well as on individual sources of variability of urea concentration in goat milk.

Recovery of efficient treatment performance in a semi-aerobic aged refuse biofilter when treating landfill leachate: Washing action using domestic sewage.

Semi-aerobic aged refuse biofilters (SAARB) are known to efficiently remove organic matter, nitrogenous substances, and anions from landfill leachate. However, long-term recirculation of mature landfill leachate inevitably leads to accumulation of pollutants and decreases treatment capacity. In this study, the washing action provided by domestic sewage was used to recover and even enhance the treatment performance of SAARBs treating mature landfill leachate. Three SAARB columns were operated for 300d after which a "Recirculation-Washing-Recirculation" sequence was followed. In the first recirculation period (22d), removal of chemical oxygen demand (COD) and total nitrogen (TN) decreased from ca. 90% and 60%, respectively, initially to about 75% and less than 20%, respectively. Thereafter, washing (20d) of the SAARBs was accomplished by applying domestic sewage. In the subsequent second recirculation period (30d), the SAARBs were operated at the same hydraulic loading as used initially, but achieved high (ca. 90%) COD and relatively high (ca. 59%-76%) TN removal, including degradation of refractory organic matter such as humic- and fulvic-like substances. Overall, the mechanisms of the treatment performance recovery (including organics degradation and nitrification-denitrification) using domestic sewage can be attributed to three main effects: (1) some accumulated pollutants were washed out, thereby leading to recovery of the adsorption ability of aged refuse; (2) the inhibition of bio-refractory organics stress on microbial activities was mitigated by domestic sewage washing; and (3) the wash out of some accumulated salts (e.g., chloride and sulfate ions) probably helped the microbial activity recover.

Textural and quality changes of hairtail fillets (Trichiurus haumela) related with water distribution during simulated cold chain logistics.

This study investigated the total viable counts, sensory and physicochemical qualities (total volatile basic nitrogen, K-value, thiobarbituric acid reactive substances value, water holding capacity and texture parameters), as well as water distribution of fresh hairtail fish during simulated cold chain. The results showed that total volatile basic nitrogen, thiobarbituric acid reactive substances and K-values increased with the increasing time, while sensory scores, water holding capacity, hardness and elasticity decreased. The transverse relaxation time T2 data detected by low-field nuclear magnetic resonance also showed that T22 (trapped water) gradually decreased with the increasing time, while T23 (free water) increased. It was observed that the quality deterioration of the fish fillets developed more quickly when the samples suffered frequent temperature fluctuations than they stored at higher but stable temperatures. The changes of T22 and T23 of both the samples stored at stable and fluctuated temperatures showed good correlations with sensory, total volatile basic nitrogen and thiobarbituric acid reactive substances values (R2 > 0.9, p < 0.05). Therefore, low-field nuclear magnetic resonance technology can be a potential tool to monitor the quality changes of hairtail fish during cold chain logistics.

Effects of nitrogenous substances on heat transfer fouling using model thin stillage fluids

Fouling is unwanted deposition of materials on surfaces of processing equipment, which leads to additional capital investment and lower processing efficiency. During fuel ethanol production, fouling occurs when thin stillage is concentrated into condensed distillers solubles. Investigations of protein impact on fouling are limited despite high protein concentration in thin stillage (17–33%db). Protein contributions to fouling have been verified in the dairy industry. Whey proteins and calcium phosphate interact with each other or other proteins and form aggregates on heated surfaces. Due to the complex biological composition of thin stillage, it is difficult to study a single effect on fouling without interference from other factors. The objective was to investigate fouling properties of nitrogenous substances (urea and yeast) using model fluids; effects of protease addition on fouling properties of model and commercial thin stillage fluids. Urea addition did not lead to fouling while glucose-yeast model fluids displayed fouling tendencies. Protease from pineapple stem (bromelain) incubation increased fouling in model and commercial fluids, which were indicative that hydrolyzed molecules such as peptides, amino acids or protease can be involved in deposit formation.

Chemical composition of sea-buckthorn and highbush blueberry fruits grown in the Republic of Belarus

Chemical composition of sea-buckthorn and highbush blueberry fruits determines their value while using them fresh or processed. Berries have distinctive characteristics depending on a variety, soil and climatic conditions and growing techniques. The object of the researches have been Sea-buckthorn (Hippophae L.) of three varieties (Podarok sadu, Trofimovskaya, Botanicheskaya) and Highbush Blueberry (Vaccinium corymbosum L.) of five varieties (Duke, Bluetta, Bluecrop, Northland, Coville) grown in the Republic of Belarus. Sea-buckthorn and Highbush Blueberry fruits chemical composition has been studied during a three-year cycle of monitoring using standard methods and in accordance with technical legal acts of the Republic of Belarus. Solid content (13,0-15,3%), sugar content (4,00-4,80%), organic acids (1,10-2,05%), nitrogen substances content (0,29-0,46%), lipids (3,6-6,2%), pectin content (0,40-0,50%), fiber (3,20-4,90%), minerals, vitamin С (44,7-78,7 мг/100г), β-carotene (4,4-13,2 мг/100г) have been studied in Sea-buckthorn (Hippophae L.). Solid content (12,2-15,1%), sugar content (2,73-3,96%), organic acids (0,59-0,95%), pectin content (0,57-0,97%), fiber (1,20-1,68%), bioflavonoids (276-368 мг/100 г), bioflavonoids complex fractional composition (anthocyanins, leucoanthocyanins, catechines, flavonols), vitamin С (60,5-72,2 мг/100 г) and mineral content have been studied in Highbush Blueberry (Vaccinium corymbosum L.). Exogenous contaminants content (arsenic, heavy metals), hygienical safety indexes, caesium 137 radionuclides content have been investigated in the fruits. Specific varieties characterictics of Sea-buckthorn (Hippophae L.) and Highbush Blueberry (Vaccinium corymbosum L.) fruit chemical composition have been determined. The studied fruit is fully safe and can be recommended to be used both fresh and processed.

A green engineering approach to simultaneously removing organic and nitrogenous substances in wastewater

This study was aimed at investigating the performance of an algae bioreactor on the simultaneous removal of organic and nitrogenous substances under varied illumination period and light intensity. An aerobic bioreactor having an effective volume of three litters was operated in fill and draw mode of four days per cycle. The algae of Chlorella sp were grown in the bioreactor fed with simulated wastewater. The bioreactor received the light, which was set with a period of 12-hour light-ON, followed by 12-hour light-OFF, and a continuous 24-hour light-ON. The light intensities were varied at various levels of 5,000; 7,500; 10,000; and 12,500 lux. The result of the research showed that the algae bioreactor was capable of removing Chemical Oxygen Demand (COD) up to 57.56% at the light intensity of 5,000 lux and up to 68.83% at the light intensity of 10,000 lux. The removal of ammonium at light intensities of 5,000 and 10,000 lux was obtained as 52,42 and 73,55%, respectively. The highest algae concentration of 1.5 × 106 individual/ml was observed at the light intensity of 10,000 lux. The above results suggested that the removal of organic and nitrogenous substances has simultaneously occurred in the algae bioreactor.

Risk factors for ineffective renal perfusion among elderly hospitalized in an ICU

Acute kidney injury (AKI) is defined as a syndrome characterized by sudden and potentially reversible loss of kidney function, leading to accumulation of nitrogenous substances (urea and creatinine). The aim of this study was to identify factors related to the risk of ineffective renal perfusion, showing associations with clinical and therapeutic characteristics. This was a retrospective, cross-sectional study with a descriptive and correlational analysis conducted in a general adult intensive care unit (ICU) of a large private hospital. The convenience sample consisted of 288 patients. All medical records of elderly patients who were admitted to the ICU from November 2016 to January 2017, regardless of their clinical diagnosis, were included. To statistically analyze the relationship between the covariates and the change in serum ICU admission and discharge values from the ICU, the ANOVA and Chi-squared tests were used. Among elderly inpatients, individuals aged between 60 and 89 years were concentrated and were mostly female. Regarding the epidemiological profile, there were more diabetes mellitus and systemic arterial hypertension comorbidities. It is noted that the elderly were exposed to many risk factors for AKI during hospitalization. The covariates that showed statistically significant results when compared with the change in urea values at ICU admission and discharge were gender, age, pre-existing nephropathies, SAH, DM and neoplasms. When the comparison was made between the covariates and the change in creatinine values, only the health problems represented by hypertension, DM, CHF and neoplasms had significant results. In this context, it is essential that nurses properly identify and plan care in the presence of risk factors for the development of AKI.

Chemical and Technological Characteristics of Fresh Roots of Four Sugar Beet Varieties Harvested at different Periods

The present investigation was carried out with an objective to understand the biochemical and technological changes that occurred in sugar beet roots of four commercial sugar beet varieties under different harvesting at different periods. For this study, four varieties of sugar beet were selected: Pleno, Top, Kawemira, and Ceres poly (P3) with high yield of roots as well as high sugar content. Moisture and ash contents were 75.66 to 81.52% and 2.34 to 3.97%; respectively, at different harvest periods. Total nitrogen content ranged between 0.65 and 2%. TSS ranged between 17.20 and 23.90%. Sucrose content of four varieties ranged between 12.40 and 19.50%.While, white sucrose percentage ranged between 8.76% and 16.35%. The purity of sugar beet roots juice of four varieties harvested at three periods ranged between 68.13% and 81.58%. Quality of fresh sugar beet roots was ranged between 70.65 and 84.58%. This investigation showed the sugar beet manufacturing at 210 days gives the lowest percentage of nitrogen substance, thus sugar percentage increased in comparison with early periods.

Performance of constructed wetlands with different substrates for the treated effluent from municipal sewage plants

Abstract Constructed wetlands (CWs) are effective as an advanced treatment process for the treated effluent of municipal wastewater plants. An appropriate substrate, suitable macrophytes, and proper operation are crucial for pollutant abatement. In this research, three subsurface flow CWs with various substrates were investigated. Pollutants abatement efficiency under various operational schemes were analyzed. The results showed that the satisfactory hydraulic loading rate was 0.25 m3/(m2·d). When the C/N ratio of influent was adjusted to 5.87 by adding a carbon source, the denitrification and dephosphorization efficiency would be improved, with 7–8 mg/L for total nitrogen (TN) and 0.4 mg/L for total phosphorus (TP) in the effluent, which can achieve the Class 1A Discharge Standard for discharge to natural waterways in China. A greater depth of submersion for the substrate layer resulted in a more conducive environment for the abatement of nitrogen substances. However, a 40-cm depth of submersion in CWs results in better removal efficiency of TN and TP. A plastic ring substrate (PRS) contains biological enzyme promoter formula, which was conducive to nitrifying and denitrifying bacteria. The biofilm affinity and coordination with plants made the PRS more effective than the other two substrates, especially for NO3–-N and TN abatement efficiency.

Molecular composition of hydrothermal liquefaction wastewater from sewage sludge and its transformation during anaerobic digestion

Anaerobic digestion (AD) has shown potential to convert hydrothermal liquefaction wastewater (HTLWW) into biogas in previous studies. However, the identification of refractory components and further insights into the molecular transformations of organics in HTLWW are essential for developing more efficient AD processes. In this study, two HTLWWs were obtained from the temperature-derived hydrothermal liquefaction of sewage sludge at 170 ℃ and 320 ℃. Their molecular compositions, as well as their modifications in the subsequent AD process, were characterized using a suite of advanced molecular tools. The dissolved organic matter (DOM) in the high temperature-derived HTLWW was lower in molecular weight, less saturated, less oxidized, and enhanced in nitrogenous substances. During the AD process, most of the volatile compounds and low molecular weight (LMW) neutrals were removed, while biopolymers were the most refractory. Carboxylic-rich alicyclic molecules (CRAM), particularly those containing 3 to 5 N for low temperature-derived DOM and 1 to 3 N for high temperature-derived DOM, were resistant to anaerobic biodegradation. Meanwhile, compounds with fewer nitrogens and more carboxyl groups were preferentially produced. This molecular characterization of HTLWW-derived DOM and examination of its transformation during AD will contribute to the development of efficient methods for HTLWW treatment in the future.

Comparative analysis of vermicompost quality produced from brewers’ spent grain and cow manure by the red earthworm Eisenia fetida

Brewers’ spent grain (BSG) is a by-product of brewing that is usually used as low-value animal feed, although it can be better exploited in biotechnological processes, such as vermicomposting. Here, the chemical, biochemical and microbiological qualities of vermicomposts produced by the earthworm Eisenia fetida were evaluated using three substrates: BSG; cow manure (CM); BSG plus cow manure (1:1; BSG/CM). Over after 5 months of bioconversion by earthworms and microorganisms (thereafter vermicomposting), BSG and BSG/CM showed reduced total organic carbon, and increased total nitrogen and total humic substances like (HSl), suggesting enhanced mineralisation and stabilisation. Suitability of BSG as substrate for earthworms was confirmed by the earthworm fatty acid profile, characterised by prevalence of C:17, C18:1, C18:2 and C18:3 fatty acids. Higher fungi and yeast abundance in BSG vermicompost was accompanied by higher dehydrogenase activity. E. coli, Salmonella spp. and Ochratoxin A levels were below the legal limits.

Hyperthermophilic composting reduces nitrogen loss via inhibiting ammonifiers and enhancing nitrogenous humic substance formation.

Composting is an efficient and economic approach used to convert organic waste into organic fertilizers. However, the substantial nitrogen loss during the composting process is one of the major disadvantages of conventional thermophilic composting (cTC). Here, we demonstrated for the first time that hyperthermophilic composting (hTC) was able to mitigate nitrogen loss by 40.9% compared to cTC after 44 days of composting in a full-scale plant. Results demonstrate a decrease in NH3 volatilization (52.4%), together with an inhibitory effect on protease (19.4-87.5%) and urease (9.1-75.2%) enzyme activities and the ammonification rate (5.2-80.1%) for hTC. Additionally, this study found that hTC could accelerate the humification process, thereby enhancing the formation of the recalcitrant nitrogen reservoir (mainly in the form of nitrogenous humic substances) and reducing the substrate for ammonification reactions. These findings suggest that hTC can significantly reduce nitrogen loss and provide insights into the role of humic substances in nitrogen retention in composting systems.

Phytoremediation potential of Vetiveria zizanioides and Oryza sativa to nitrate and organic substance removal in vertical flow constructed wetland systems

The aim of this work was to determine the potential of phytoremediation of Vetiveria zizanioides and Oryza sativa to nitrate (NO3−-N) and organic matter (COD – chemical oxygen demand) removal in subsurface vertical flow constructed wetland systems (VFCWs). The tests were carried out in models of 2 beds with a surface of 0.24 m2 and depth 0.70 m each at various hydraulic loads (HL) and COD constant in influente wastewater. The VFCW-1 bed was planted with the Vetiveria zizanioides and the VFCW-2 bed with the Oryza sativa. During the 22 weeks of research, the hydraulic load of the analyzed beds was: HL1 = 148 dm3·m−2·d−1, HL2 = 239 dm3·m−2·d−1, HL3 = 350 dm3·m−2·d−1, HL4 = 473 dm3·m−2·d−1. The VFCWs were fed from two reservoirs, one with mineral medium and nitrate, and the other one with fructose as organic matter. Based on the conducted tests, it was found that in both analyzed systems (VFCW-1 and VFCW-2) the highest NO3−-N removal rate was found under HL2 – the median is 59 and 42% respectively. The most effective removal of COD in the VFCW-1 system was obtained at a HL2 – 55%, while in the system VFCW-2 at a HL1 – 43%. The research shows that the low HL and high COD/NO3−-N ratio ensures good effects of nitrate and organic matter removal in VF type constructed wetland systems. It has been shown that the analyzed plants, especially Vetiveria zizanioides have good phytoremediation potential in the field of nitrate nitrogen and organic substance removal and can be recommended for use on a full scale of technology.

Dry matter yield, growth index, chemical composition and digestibility of Marandu grass under nitrogen and organic fertilization

A pasture composed of the forage Brachiaria brizantha cv. Marandu, for more than 15 years and never fertilized, with an initial condition of degradation, was fertilized with nitrogen and humic substances, with the purpose Of recovering the vigor and productivity of the pasture. In the two years (December of 2012 to April 2013 and December 2014 to April 2015), analyses were made for dry matter production, plant height, light interception, leaf / stem ratio), chemical composition and digestibility of Brachiaria brizantha cv. Marandu. This was a completely randomized block experimental design, in a 5x4 arrangement, with five doses of nitrogen (0, 50, 100, 200, 400 kg N.ha-1), four doses of humic substances (0, 12.5, 25 and 50%), with 5 replicates. The forage presented lower means of dry matter production in the first year in relation to the second, but there was no difference for the chemical composition and digestibility between the years. There was a significant effect of Nitrogen levels on the production of dry matter, crude protein, silica, neutral detergent fiber (NDF), acid detergent fiber (FDA), and in vitro dry matter digestibility (DVMS). The best response was obtained with 200 kg N.ha-1. The doses of humic substances influenced only reducing the leaf/stem ratio, but there was no effect of doses of humic substances on the other variables studied.

Is edible insect as a novel food digestible?

This work deals with the digestibility of a selected species of edible insect - mealworm (larvae) as novel food in dependency on its culinary treatment. The aim of this work was to find suitable thermic culinary treatment of mealworm larvae considering its optimum digestibility by human. The digestibility of materials from whole insect and extracted nitrogenous substances was determined using three different culinary treatments - without culinary treatment (freshly killed), dried insect and roasted insect. The digestibility was determined by gravimetric in vitro method using pepsin and pancreatin enzymes and their combination. The total nitrogen content of the insect samples was determined by the Kjeldahl method. The digestibility of the whole homogenized larvae using the combination of pepsin and pancreatin enzymes, thus simulating human digestion in-vitro, ranged from 81% for roasted specimens to 91.5% for culinary unprocessed insect. Similarly, the digestibility of nitrogenous substances of homogenized insect samples using this combination of enzymes ranged from 24.2% for roasted specimens to 80.2% for culinary unprocessed samples. The work showed the dependence of the digestibility of the mealworm larvae on the culinary treatment - the increasing heat load of the sample reduced the digestibility. Furthermore, it proved the effect of the digestive enzyme on the digestibility of the insect sample.&#x0D;

Strengthened dewaterability of coke-oven plant oily sludge by altering extracellular organics using Fe(II)-activated persulfate oxidation

Although oily sludge has tremendous resource recovery value, its high water content has hindered its treatment and reuse. This study systematically explored the technical feasibility of using Fe(II)-activated persulfate oxidation (Fe2+/S2O82−) to enhance the dewaterability of oily sludge. To identify the main factors controlling sludge dewatering, this study measured changes in chemical oxygen demand, ammonia nitrogen (NH4+-N) and extracellular polymeric substances (EPS). Results showed that at 0.1 mmol-Fe2+/g-VSS and 0.08 mmol-S2O82−/g-VSS, capillary suction time (s) was reduced by roughly 36.1% within 1 min and dewaterability was strengthened strongly. Sulfate radicals originating from Fe2+/S2O82− oxidized a large amount of EPS, leading to liberation of EPS-bound water. A similar declining trend in NH4+-N was evident as a result of the strong oxidizing ability of sulfate radicals. Further analysis via scanning electron microscopy and thermogravimetric-Fourier transform infrared spectrometry revealed that Fe2+/S2O82− oxidation destroyed the water-oil-gel-like structure of the oily sludge, thereby accelerating the separation of solids and water while reducing CO2 emissions during the subsequent pyrolysis. Therefore, oily sludge dewatering was enhanced significantly by the Fe2+/S2O82− process.