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Peat is an unrenewable resource. Compost can partially replace peat in the growing seedling substrates due to its high electrical conductivity (EC), bulk density (BD), and pH. This study aimed to assess the potential of substituting peat for seedling substrate with compost made from a mixture of agricultural and agro-industrial wastes. Four compost piles (C1–C4) were constructed as follows: C1: a 1:1:1.5 weight ratio mixture of filter mud, mushroom waste, and date-palm fronds, while C2–C4: a 0.5:1 weight ratio mixture of either bagasse, cutting grassland, or date-palm fronds and cattle dung. After four months of decomposition, the compost's physical, chemical, and biological properties were estimated in comparison to commercial compost (CC), peatmoss (PM), and their ideal ranges (IR) for seed germination and seedling growth. Composts differed significantly in their physical and chemical properties. Some composts revealed property values within the IR. In comparison to PM, Composts have a lower C/N ratio and organic matter, along with higher BD, EC, and pH. Cattle manure enhanced organic matter and carbon, total nitrogen and potassium, and ammonium levels, and reduced ash levels in C2–C4 compared to filter mud in C1. In winter 2018 and 2019, C1–C4 substrates were compared with CC and PM substrates to determine their suitability for producing crisp lettuce 'Big Bell' seedlings under plastic-house conditions. Substrates had significant effects on lettuce seedling traits. Shoots of C2–C4 substrate seedlings grew more rapidly than those of other substrate seedlings due to the increased length and diameter of their stem and leaf area. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the feasibility of producing biogas by combining solid poultry slaughterhouse wastes (SPSWs) with fruit and vegetable solid wastes (FVSWs) and to obtain the optimum conditions for maximum biogas production by means of anaerobic digestion (AD). The ratio of available carbon to available nitrogen (C/N), as a critical parameter in producing methane, was adjusted by mixing the appropriate amount of SPSWs with FVSWs. For each load, a 50-L pilot-scale digester was operated for 40 days. For start-up and seeding, the biogas reactor was bioaugmented using the anaerobic sludge of an industrial poultry wastewater treatment plant. The analyzed SPSW, which had a C/N ratio of 5.75, was combined with FVSWs to obtain C/N ratios of 20, 30, and 40. Furthermore, it was found that the highest biogas yield occurred when the C/N ratio of the feed was 30. Also, for all three loading ratios, biogas production volumes were 215.1, 241, and 182.7 L, respectively, where methane's shares were 104.5, 120.6, and 91.7 L of the total gas volume that constituted 48.6, 50, and 50.2% of the produced biogas. Therefore, the obtained results from the process of mesophilic AD of this type of solid wastes illustrate that it is possible to efficiently produce biogas as a renewable energy source by combining SPSWs and FVSWs, instead of burning or burying them. [ABSTRACT FROM AUTHOR]

Bio‐based 2,3‐butanediol (2,3‐BDO) production on a large scale depends on critical factors, such as culture medium, oxygen supply, pH and biosafety. In this study, three strategies for reducing culture medium costs were investigated: carbon/nitrogen (C/N) ratio; low‐cost nitrogen sources (crude yeast extract, brewer's yeast extract, corn steep liquor, urea, sodium nitrate, ammonium chloride, ammonium sulfate and dibasic ammonium phosphate); and microbial pH autoregulation. Batch fermentations were performed in a microaerobic environment using wild‐type and safe Paenibacillus peoriae NRRL BD 62. The yield and selectivity of 2,3‐BDO were used as control variables. A ratio between 2,3‐BDO production and glucose consumption (YP/S) of almost 80% and an optical purity of 87% levo‐2,3‐BDO, with no acetoin accumulation, were achieved in an NH4Cl‐based medium at C/N = 8.5 g/g and without external pH control, considering an initial glucose of 10 g/L. Based on Free on Board prices, a 63% savings in culture medium costs was achieved by replacing commercial yeast extract at pH 5. Validation assays with higher initial glucose concentrations showed a YP/S of 0.40 g/g and an optical levo‐/meso‐2,3‐BDO ratio of 1:0.8, with negligible acetoin accumulation. Therefore, the NH4Cl‐based medium at C/N = 8.5 g/g and without pH control was considered economically promising for high‐yield and high‐selectivity bio‐based 2,3‐BDO production. [ABSTRACT FROM AUTHOR]

Biofuel can be generated by different organisms using various substrates. The green alga Chlorococcum humicola OQ934050 exhibited the capability to photosynthesize carbonate carbon, maybe via the activity of carbonic anhydrase enzymes. The optimum treatment is C:N ratio of 1:1 (0.2 mmoles sodium carbonate and 0.2 mmoles sodium nitrate) as it induced the highest dry mass (more than 0.5 mg.mL−1). At this combination, biomass were about 0.2 mg/mL−1 carbohydrates, 0.085 mg/mL−1 proteins, and 0.16 mg/mL−1 oil of this dry weight. The C/N ratios of 1:1 or 10:1 induced up to 30% of the Chlorococcum humicola dry mass as oils. Growth and dry matter content were hindered at 50:1 C/N and oil content was reduced as a result. The fatty acid profile was strongly altered by the applied C.N ratios. The defatted leftovers of the grown alga, after oil extraction, were fermented by a newly isolated heterotrophic bacterium, identified as Bacillus coagulans OQ053202, to evolve hydrogen content as gas. The highest cumulative hydrogen production and reducing sugar (70 ml H2/g biomass and 0.128 mg/ml; respectively) were found at the C/N ratio of 10:1 with the highest hydrogen evolution efficiency (HEE) of 22.8 ml H2/ mg reducing sugar. The optimum treatment applied to the Chlorococcum humicola is C:N ratio of 1:1 for the highest dry mass, up to 30% dry mass as oils. Some fatty acids were induced while others disappeared, depending on the C/N ratios. The highest cumulative hydrogen production and reducing sugar were found at the C/N ratio of 10:1. [ABSTRACT FROM AUTHOR]

Garbage, especially organic garbage, is created in higher numbers due to population development, and conventional markets are the main source of waste. Waste that is not managed appropriately will result in environmental pollution. However, compost can be generated from organic waste that comes from market garbage. Compost fertilizer is made by blending balanced components and managing aeration using a compost starter. One of the most important components of the overall nutritional balance is the ratio of organic carbon to nitrogen. This study used various bioactivators to calculate the C/N ratio of market waste. First, as part of the investigation, organic market trash is composted. The C/N ratio in the control, EM4, MOL, and rabbit urine treatments must subsequently be explained in the laboratory. Based on the research findings, C/N was 8 in control treatment and 4.35 in EM4 therapy. In the MOL therapy, the value was 6.69, whereas in the rabbit urine treatment, it was 8.18. None of these four treatments were able to achieve the compost quality parameters according to the regulations. [ABSTRACT FROM AUTHOR]

Abstract Biofuel can be generated by different organisms using various substrates. The green alga Chlorococcum humicola OQ934050 exhibited the capability to photosynthesize carbonate carbon, maybe via the activity of carbonic anhydrase enzymes. The optimum treatment is C:N ratio of 1:1 (0.2 mmoles sodium carbonate and 0.2 mmoles sodium nitrate) as it induced the highest dry mass (more than 0.5 mg.mL−1). At this combination, biomass were about 0.2 mg/mL−1 carbohydrates, 0.085 mg/mL−1 proteins, and 0.16 mg/mL−1 oil of this dry weight. The C/N ratios of 1:1 or 10:1 induced up to 30% of the Chlorococcum humicola dry mass as oils. Growth and dry matter content were hindered at 50:1 C/N and oil content was reduced as a result. The fatty acid profile was strongly altered by the applied C.N ratios. The defatted leftovers of the grown alga, after oil extraction, were fermented by a newly isolated heterotrophic bacterium, identified as Bacillus coagulans OQ053202, to evolve hydrogen content as gas. The highest cumulative hydrogen production and reducing sugar (70 ml H2/g biomass and 0.128 mg/ml; respectively) were found at the C/N ratio of 10:1 with the highest hydrogen evolution efficiency (HEE) of 22.8 ml H2/ mg reducing sugar. The optimum treatment applied to the Chlorococcum humicola is C:N ratio of 1:1 for the highest dry mass, up to 30% dry mass as oils. Some fatty acids were induced while others disappeared, depending on the C/N ratios. The highest cumulative hydrogen production and reducing sugar were found at the C/N ratio of 10:1.

The present study compared the supplementation of Litopenaeus vannamei tanks with inoculums generated by different nitrogen sources (NH4Cl or feed). The interactions of inoculums and C/N adjustment strategies on water quality and growth performance were also investigated. After preparation of inoculums, shrimp juveniles were reared for 39 days at 142 shrimps/m3 in four treatments: T1, NH4Cl-based inoculum + heterotrophic C/N adjustment; T2, NH4Cl-based inoculum + mixotrophic C/N adjustment; T3, feed-based inoculum + heterotrophic C/N adjustment; and T4, feed-based inoculum + mixotrophic C/N adjustment. At the end, two-way ANOVA analysis showed significant interactions of time × inoculum or time × C/N adjustment strategy on dissolved oxygen, pH, and settleable solids. Alkalinity was significantly affected by the time × C/N adjustment strategy interaction, while inorganic nitrogen species (TAN, NO2-N, and NO3-N) were altered depending on the time × inoculum effect. Inoculum and C/N adjustment strategy significantly altered alkalinity and TAN levels. TAN levels in T1 and T2 treatments accumulated for 2 weeks, and organic carbon addition was not effective in mitigating high TAN levels. The mixotrophic strategy significantly reduced solids levels, while enhancing DO levels. No significant interactive effects of inoculum × C/N adjustment strategy were detected on the water quality indicators. The final body weight (FBW), feed conversion ratio (FCR), and weekly growth rate (WGR) of shrimp were significantly improved in tanks supplied with feed-based inoculum. Also, the inoculum × C/N adjustment strategy led to significantly higher FBW, weight gain, specific growth rate, and WGR in tanks supplied with feed-based inoculum and heterotrophic C/N adjustment. In conclusion, feed-based inoculum prevented the accumulation/peak of nitrogen species, reduced the nitrification establishment time, and enhanced growth performance. In addition, inoculum effectiveness was affected by the C/N adjustment strategy, highlighting the advantageous performance of mixotrophic approach. This information can develop efficient management practices for biofloc systems. [ABSTRACT FROM AUTHOR]

A 40-cm core of lake-bottom silt from Yercaud Lake (Eastern Ghats, south India) dates from 2500 years ago to the present, as confirmed by AMS radiocarbon dating. The average deposition rate varied from 0.024 to 0.008 cm/yr. Sediment particle size distribution, stable isotopes (δ13C and δ15N), C/N, and total organic carbon (TOC) were investigated as indicators of environmental change. In the top 10 cm are the coarsest sediments, which range from silt to silty sand and have a TOC of up to 5%. Algal lacustrine organic matter is combined with terrestrial or wetland organic matter from vascular plants to form organic matter (OM) with a C/N ratio of 12–18. High C/N levels are associated with low 13C and high TOC contents, indicating periods of drier climate between 0–500 and 800–2000 years BP. Grain-size characteristics, which fluctuate independently of OM qualities, are likely to have changed because of intensive human use of the lake basin in the past 600 years. Climate changes observed in OM do not correspond to changes observed in other south Indian lakes where precipitation is primarily from the southwest monsoon. [ABSTRACT FROM AUTHOR]

A lot of fish waste is produced by the community, both from the marketing sector and the fisheries sector, which is caught by fishermen. Almost 35% of the fish waste produced is in the form of heads, bones, innards and also fish remains that are not the main catch which are thrown away directly. Vermicomposting is one of method to reduce the amount of fish waste. The adding of livestock manure in vermicomposting will increase the quality of compost. The purpose of this research is to analyze the compost quality with the mixture of fish waste and livestock manure. The results showed that The compost that has the best quality based on SNI 19-7030-2004 is B2 with 45% fish waste, 20% cow dung and 35% sawdust with a dose of EM4 10 ml, which has a final temperature of 29ºC, pH 7, water content 41%, C-organic 19.83%, nitrogen 1.34%, phosphorus 0.36%, potassium 1.15%, and C/N ratio 14.85. Then, after incubating the soil improvement, it was found that the addition of compost can improve the chemical characteristics of the soil according to the dose given. This indicates that compost application can affect soil quality. Soil quality that has C-organic and nitrogen content according to BPT in 2009 is with the addition of a dose of 5.2 grams of vermicompost. The shortcomings of this study are that the phosphorus and potassium levels are too high.

The present study investigates the synergistic impact of earthworms (Eisenia fetida and Eudrilus eugeniae) and microbes during vermicomposting of invasive weed phytomass (Xanthium strumarium and Lantana camara). This study aims introducing an onsite solution for weed control while producing valuable organic manure. Vermitransformation and detailed characterization of mono- (VC1, VC2, VC4, VC5) and polyculture (VC3, VC6) of X. strumarium and L. camara has been reported for the first time employing E. fetida and E. eugeniae. The study achieved 45.16 ± 2.48–76.73 ± 1.37% vermiconvertion rate. The pH, conductivity, and concentration of heavy metals are effectively stabilized. Furthermore, it observed a significant reduction in total organic carbon (TOC) alongside the augmentation of nitrogen, phosphorus, potassium, calcium, and other trace elements (Zn, Ni, Fe). The ash content, humification index, and C/N ratio analysis established the maturity of the vermicompost. The macronutrient enhancement in the vermicompost samples was recorded 1.5- to 2.47-fold for total N, 1.19- to 1.48-fold in available P, 1.1- to 1.2-fold in total K, and 1.1- to 1.18-fold in total Ca. The germination index reveals a significant reduction in phytotoxicity, suggesting the production of mature and suitable vermicompost for agricultural use. Evaluating mono- and polyculture techniques, the research highlights the superiority of E. fetida over E. eugeniae. Further, the earthworm population and biomass have significantly increased by the end of 60-day experimental trial. [ABSTRACT FROM AUTHOR]

Water quality and growth of Litopenaeus vannamei were monitored at different stocking densities in a zero-water exchange nursery system inoculated with chemoautotrophic bacteria and limited organic carbon (OC) addition. Shrimp (∼3.4 mg) were divided into four groups of 200 PL/m2 (T200), 500 PL/m2 (T500), 1000 PL/m2 (T1000), and 1500 PL/m2 (T1500). At the end of the study, the water temperature, pH, salinity, dissolved oxygen, oxidation-reduction potential, and dissolved oxygen saturation were within the optimal range. Total dissolved solids and electrical conductivity were lower in T200. The highest concentrations of free CO2 were observed in T1500. The results also revealed higher levels of alkalinity in T1500 compared to T500 and T1000. Notably, TAN was lower in T200 than in T1000 and T1500. Nitrite nitrogen (nitrite-N) and nitrate nitrogen were also lower in T200. Furthermore, TAN and nitrite-N levels rapidly elevated upon OC addition. Interestingly, nitrite-N levels exhibited a decrease whenever OC application was terminated. Total heterotrophic and Vibrio sp. bacteria in water samples were not affected by study groups. Regarding growth performance, T200 had significantly better final weight, weight gain, specific growth rate, and weekly growth rate. However, T1500 had the highest shrimp yield (kg/m3 or kg/m2). In conclusion, OC in the chemoautotrophic system interferes with the nitrification cycle, disrupts the effective conversion of nitrogen, and leads to further deterioration of water quality and shrimp growth performance at higher stocking densities. In this system, shrimp at the lowest density (200 PL/m2) reached the highest final weight and survival. [ABSTRACT FROM AUTHOR]

Vermicomposting of bakery sludge (BS) was studied when amended with fruit-vegetable waste (FV) and cow dung (CD) with different proportions in vermi-units (VU): VU1(CD100), VU2(CD75BS25), VU3(CD50BS25FV25), VU4(CD25BS25FV50), and VU5(CD25 BS50FV25). Results showed a reduction in pH and total organic carbon and an increase in electrical conductivity, ash content, nitrogen, phosphorus, and potassium after vermicomposting. Carbon/nitrogen decrease followed: VU3 > VU1 > VU4 > VU2 > VU5, whereas a maximum reduction in carbon/phosphorus (60.7%) was observed in VU3 and a minimum (44.8%) in VU5. Seed germination assay of Cicer arietinum was 71–138% with maximum in VU3. Respiration rates of 69–115 mgCO2 kg−1VC48h−1 were achieved signifying stability and non-toxic impact. The presence of FV waste in vermi-units enhanced earthworm population, biomass, growth rate, and cocoons. VU3 exhibited higher macro- and micronutrients as well as worm growth and fecundity over other vermi-units. Based on results, FV waste and CD amendment at 25% and 50%, respectively, are suggested as appropriate to produce enriched vermicompost from BS using Eisenia fetida. [ABSTRACT FROM AUTHOR]

A 35-day study investigated the impact of carbon sources and carbon/nitrogen (C/N) ratios on the microbial community of biofloc. For this purpose, we utilized a combination of phospho-lipid fatty acids (PLFAs) profiles and DNA-based sequencing methods to investigate changes in the microbial community composition and structure. The experiment involved three carbon sources including Dextrin (DEX), corn starch (CS) and wheat bran (WB) at two C/N ratios (19 and 30). The results indicated that WB and CS were found to decrease nitrogen metabolite concentration while increasing total suspended solids and bacterial density compared to DEX. The treatments exhibited variations in microbial communities and the use of polymerase chain reaction/ denaturing gradient gel electrophoresis analysis revealed distinct dominant bacterial species linked to carbon sources and C/N ratios. Furthermore, the highest levels of bacteria and protozoa PLFAs biomarkers were observed in the C/N30 ratio and WB treatment while the ratio for poly-β-hydroxybutyrate/PLFAs and fungi biomarkers displayed a decrease. Also, by incorporating the results of PLFAs profile and conducting a principal component analysis, the treatments were categorized into distinct groups based on both the carbon source and C/N ratios. Overall, both methods yield consistent results. PLFAs offered additional insights into the microbial composition beyond bacterial structure while DNA-based analysis provided finer taxonomic resolution. [ABSTRACT FROM AUTHOR]

The glutamine synthetase/glutamic acid synthetase (GS/GOGAT) cycle plays important roles in N metabolism, growth, development, and stress resistance in plants. Excess ammonium (NH4+) restricts growth, but GS can help to alleviate its toxicity. In this study, the 84K model clone of hybrid poplar (Populus alba × P. tremula var. glandulosa), which has reduced biomass accumulation and leaf chlorosis under high-NH4+ stress, showed less severe symptoms in transgenic lines overexpressing GLUTAMINE SYNTHETASE 1;2 (GS1;2 -OE), and more severe symptoms in RNAi lines (GS1;2 -RNAi). Compared with the wild type, the GS1;2 -OE lines had increased GS and GOGAT activities and higher contents of free amino acids, soluble proteins, total N, and chlorophyll under high-NH4+ stress, whilst the antioxidant and NH4+ assimilation capacities of the GS1;2 -RNAi lines were decreased. The total C content and C/N ratio in roots and leaves of the overexpression lines were higher under stress, and there were increased contents of various amino acids and sugar alcohols, and reduced contents of carbohydrates in the roots. Under high-NH4+ stress, genes related to amino acid biosynthesis, sucrose and starch degradation, galactose metabolism, and the antioxidant system were significantly up-regulated in the roots of the overexpression lines. Thus, overexpression of GS1;2 affected the carbon and amino acid metabolism pathways under high-NH4+ stress to help maintain the balance between C and N metabolism and alleviate the symptoms of toxicity. Modification of the GS/GOGAT cycle by genetic engineering is therefore a potential strategy for improving the NH4+ tolerance of cultivated trees. [ABSTRACT FROM AUTHOR]

High carbon content and high‐level biodegradability are major constraints of the anaerobic digestion of food waste. In the present study, anaerobic digestion of model food waste was carried out in a fed batch digester. Nitrogen content in model food waste was adjusted by the addition of ammonium chloride at the desired C/N ratio. Biogas production at ammonium chloride percentages of 0, 0.8, 1.5, 2.14, and 3.2 % (weight basis) were carried out under mesophilic conditions in a pilot plant scale floating drum digester. At an ammonium chloride percentage of 1.5 % that balances C/N ratio 25, highest biogas production of 0.42 m3 kg−1 of VS was attained while biogas production from food waste without ammonium chloride of 0.06 m3 kg−1 of VS was obtained. The highest methane yield of 0.323 m3 kg−1 of VS was found at ammonium chloride of 1.5 % while methane yield of 0.042 m3 kg−1 of VS was achieved from food waste without ammonium chloride. The highest percent increase CH4 yield of 669 % was obtained at an ammonium chloride percentage of 1.5 %. Biogas productivity obtained at ammonium chloride percentage of 1.5 % was 0.6 L L−1 d−1. Hence, the optimum ammonium chloride percentage obtained was 1.5 % which balances the C/N ratio at 25. [ABSTRACT FROM AUTHOR]

The study evaluated the decomposition and mineralization of pineapple and sorghum litter applied to the surface and subsurface of a Cambisol. The experiment was conducted in pot using pre-treatment (dry oven and fragmented), in a completely randomized design with four replications, following a 2 × 2 × 9 factorial consisting of two plant litters (pineapple and sorghum), two managements (surface and subsurface), and nine incubation times (0, 14, 28, 42, 56, 70, 84, 98, and 112 days after application-DAA). The remaining dry mass, the t1/2 (half-life), and macronutrient mineralization were evaluated (N, P, K, Ca, and Mg). The pineapple litter showed the highest loss compared to sorghum litter. Ca and Mg showed the longest half-life and the lowest mineralization rate regardless of the management. The allocation of pineapple and sorghum litter to the soil subsurface favors nutrient mineralization, contributing to the potential release of 82 to 99 kg ha−1 of N, 9 to 17 kg ha−1 of P, and 286 to 401 kg ha−1 of K, respectively, after 112 days. At least 50% of these nutrients were mineralized between four and 35 days, highlighting the litter potential as a nutrient source for tropical crops. [ABSTRACT FROM AUTHOR]

A growing paddy crop produces large quantities of parboiled rice mill wastewater (PRMWW), which contains several organic and inorganic compounds and nutrients (nitrogen and phosphate). Discharges of the rice industry's wastewater pose a substantial threat to aquatic bodies and the surrounding environment, so an eco-friendly treatment plan is necessary. Parboiling stands out among grain-processing methods due to its numerous nutritional and physical advantages. Fewer literatures have only mentioned about the severity of the organic rich liquid effluents generated after parboiling process. Generating renewable energy from anaerobic digestion (AD) is one of the most environmentally friendly technologies to address the growing energy demands. This study is intended to give a systematic and critical review of the parboiling process, solid and liquid fractions of wastes generated, and various treatment options, with special emphasis on scope of application of AD for treating PRMWW along with energy recovery. The study explains various glitches in the AD processes of PRMWW for biogas generation and also recommends co-digesting PBMWW with other carbonaceous organic substrates for improved digestibility, and to reduce the inhibitions caused by lack of alkalinity, acid accumulation, and pH imbalance. To this end, this literature review seeks to provide a broad overview of knowledge to laypeople, entrepreneurs, and researchers. [ABSTRACT FROM AUTHOR]

Background: The respiratory quotient, that is, the CO2–O2‐exchange ratio during aerobic heterotrophic soil respiration, (RQAHR) is one of the key variables of the barometric process separation (BaPS) technique. For reliable application, the BaPS method requires the adjustment of RQAHR to soil‐specific substrate conditions. Aim: The objective of the present study was to determine RQAHR in five arable soils varying between pH 4 and 8 and carbon/nitrogen (C/N) ratios between 8.4 and 11.9 using the BaPS–15N method. Further, we aimed to elucidate whether RQAHR can be estimated from basic soil properties. Results: Determined RQAHRs were soil specific and ranged between 0.74 and 1.53. RQAHR particularly affected the calculation of gross nitrification rates but not soil respiration rates. Based on a multiple linear regression analysis, soil pH and the C/N ratio of the soil organic matter pool were identified to explain well (R2 = 0.984) the measured RQAHRs. Applying the thus derived RQMLR to the calculation procedure led to good agreement between gross nitrification rates derived by the 15N pool dilution technique. Conclusions: Future studies are needed to test whether this empirical relationship between RQAHR, pH, and C/N ratio is generalizable. If this would be the case, the BaPS method could be applied without the use of a stable isotope and thus, being less resource demanding than the 15N pool dilution technique. [ABSTRACT FROM AUTHOR]

The increasing invasion of Rugulopteryx okamurae algae along the coast of southeastern Spain has prompted efforts to explore its potential as a resource. Consequently, composting this alga is considered a viable solution for agricultural applications. This study investigates the composting process of mixtures of R. okamurae seaweed with plant residues and characterizes the final compost for its use as a substrate and/or source of nutrients to determine the most effective composition of the mixture. The composting process was conducted using varying proportions of seaweed (100%, 30–35%, and 15%) combined with plant residues (from vegetable plants, fruits, and gardens) and included both washed and unwashed seaweed. The first trials revealed challenges associated with Rugulopteryx okamurae, such as a low C/N ratio and algae washing. Consequently, a second trial was conducted to optimize the mixtures, aiming for a C/N ratio close to 30. Additionally, it was decided not to wash the algae to reduce the electrical conductivity (EC) in the mixtures. The findings indicate that the composting process remains unaffected by high electrical conductivity when algae are unwashed. However, washing the algae before composting did affect the compost quality, as the composts with washed algae with garden waste (SwP 34.0 dS m−1) had a lower electrical conductivity (EC) than did the unwashed composts with garden waste (SP 51.6 dS m−1 and SFP 64.9 dS m−1). On the other hand, the compost-only horticultural and garden waste (FHP 43.7 dS m−1) had a high EC; therefore, the EC was not increased with low proportions of unwashed algae, as was seen with the compost with 15% unwashed algae (SFHP 47.6 dS m−1). The other quality parameters were not affected by the absence of algae washing at the beginning of the composting process. [ABSTRACT FROM AUTHOR]

Manure application performed in autumn requires regulation due to the risk of nitrogen (N) leaching during winter. On the other hand, application of manure in spring can pose some practical problems depending on the risk for N immobilization and the difficulty in ploughing heavy clay soils during this time of year. The risk for leaching is likely to differ between different soil texture and manure characteristics. In this study, we sought to estimate the risk for nitrogen leaching depending on the carbon/nitrogen ratio (C/N) of the manure, time for manure application, and soil type. We combined 3-year lysimeter experiments with 2-year field plot experiments and laboratory soil incubations and compared results with those from an empirical model. We compared effects of manure application on two soils (silty clay and loamy sand) and solid manures with different representing C/N ratios. In incubations, only manure with a C/N-ratio below 14 contributed with significant amounts of leachable N during the first months after application. In the lysimeter study, N leaching was unaffected by the timing of the application of the manure with C/N-ratio 18. However, regarding manure with C/N-ratio 10, N leaching was elevated with 10–15 kg N per ha after manure application in October compared to November and March on both soil types. The mineral N analyses from soil profiles in the field experiments showed a similar pattern, however, the increase was higher on the loamy sand compared to the silty clay. The ammonia emissions did not differ between manure types, but were on average 24% of applied NH4-N after application in October when air temperature was on average 12°C compared to only 3% of applied NH4-N in November and March when air temperature was on average 5°C. Similar to lysimeter results, the modelled N leaching was higher the earlier the manure application occurred in autumn. However, the model also predicted increased leaching for the manure with a high C/N-ratio, and a smaller effect on leaching on clay soil. Considering this, the model calculations overestimated the leaching effects from manure with a high C/N-ratio and underestimated the leaching effects on clay soil.

Extended Abstract Background: Afforestation has been growing worldwide in recent decades and is expected to continue in this trend due to the increased use of wood. Therefore, the mass planting of pine trees and other fast-growing species for industrial wood production has intensified since the beginning of the 20th century. In Iran, with a low forest per capita (0.17 ha), per capita plans to create a forest and rehabilitate degraded forests to increase green space have been implemented with non-native species. For this reason, many non-native conifer species have been introduced to the country, which has not been successful in some areas. Therefore, for the success of afforestation with non-native species, it is necessary to select those that are suitable for the habitat conditions, adapt the ecological needs to the environment, and consider the effect of afforestation on the soil, understory plants, and living organisms. Ensuring sustainable management depends on knowing the effects of planted tree species on species diversity, structure, and ecosystem function. Since different tree species have different effects on soil characteristics in ecosystems, they can change soil properties with different mechanisms. In other words, the differences in litter quality, the state of nutrients, the performance of roots in nutrient uptake, the leaf structure, the crown of the tree, the microclimate under the crown, and finally the biological communities in different tree populations change the soil physicochemical properties. In general, the restoration of degraded forest lands through afforestation has a significant effect on the variability of soil characteristics, in which a major difference is observed between native and non-native species as well as broadleaf and coniferous species. Since broad-leaved tree species can positively affect the soil quality of conifer stands, this research aims to compare some soil physicochemical characteristics under the influence of pure and mixed Norway spruce (Picea abies L.) afforestation. Methods: The studied area is in the southeast of section 101 of the Makarood series, watershed 36 (Kazemroud) in Kalardasht city and at an approximate height of 1200 m. It includes the afforested areas of pure Norway spruce (PS) (2 ha), mixed Norway spruce (MS) (2.5 ha) forestry areas, and barren land (BL) (3 ha). Three transects in each area were planned due to the smallness of the areas and the need to adopt a method that best describes the condition of the soil in each area. Then, on the 10, 50, and 90 m points of the transects, soil samples were taken in layers of 0-10 and 10-30 cm (in each area, nine soil samples for each layer). The texture, saturation percentage (SP), electrical conductivity (EC), pH, neutralizing substances or lime (T.N.V), organic carbon (O.C), nitrogen (N), phosphorus (P), potassium (K), and bulk density (BD) was examined in the laboratory. Results: The bulk density was lower in the 0-10 cm layer in the MS stand (2.28 g/cm3) than in the other two areas. The soil saturation was higher in the upper layer in the PS stand (85.77%) than in the MS stand (59.83%) and BL (51.07%). On the contrary, it was greater in the lower layer of the BL (94.40%) than in the two forest stands. EC values were lower in both upper (0.40 ds/m) and lower (0.38 ds/m) layers in the BL than that in PS and MS stands. The pH was significantly lower in the 0-10 cm layer in the PS (4.84) and MS (4.88) stands than in the BL (5.75). In each of the three areas, the amount of lime was zero in the upper and lower layers. O.C. in the upper layer was significantly higher in the PS (2.57%) and the MS (2.96%) stands than in the BL (1.45%), and the highest value was measured in the MS stand (0.94%) in the lower layer. Nitrogen was higher in the upper layer of PS (0.197%) and MS (0.270%) stands than that in the BL (0.143%). It was higher in the lower layer of the MS stand (0.09%) than the PS (0.02%) and BL (0.03%) stands. The C/N was highest in the upper layer in the PS stand (12.97), but this ratio was not significantly different in the lower layer of the three areas (10.82-11.50). The amount of P was highest in the upper layer in the MS stand (8.4 ppm), but no significant difference in P was detected in the lower layer among the three areas (3.57-5.60 ppm). K content was higher in the upper layer of the PS stand (203.43 ppm), but it was higher in the BL (193.50 ppm) in the lower layer than in the two forest stands. Conclusion: In the upper soil layer (0-10 cm), pH, C, and N values did not differ between MS and PS stands, but BD and C/N were lower in the MS stand; on the contrary, soil porosity and P and K contents were higher than those in the PS stand. From this research, it is generally concluded that afforestation with MS has a better effect on the optimization of physical and chemical characteristics in the soil layers than PS, which can provide the basis for more suitable growth of trees and a better balance of the forest.

In the present study, a field establishment was initiated in 2018 with eight treatment conditions using biochar application rates of 0, 10, 20, or 30 t/ha and nitrogen application rates of 0 or 150 kg/ha. After two years, the impact of biochar on carbon-nitrogen distributions, soil aggregate stability, and wheat yields was then assessed. The predominant mechanical aggregates after two years were > 5 mm and 2-5 mm granular aggregates, with notable increases in the amounts of these aggregates following the application of biochar with or without nitrogen that coincided with an increase in soil aggregate mechanical stability. Relative to control conditions, aggregate mean weight diameter (MWD) and geometric weight diameter (GMD) values rose by 17.6% and 24.3% for biochar with nitrogen treatment (N: 150 kg/ha; biochar: 20 t/ha), respectively. Biochar application alone and the application of both biochar and nitrogen fertiliser were associated with 6.4-20.2% and 20.7-42.7% increases in spring wheat yields, respectively. Overall, the results of these analyses highlight the value of applying biochar to improve soil quality and boost crop yields proximal to the study site. This study provided the scientific basis for the rational fertilisation and scientific management of biochar combined with nitrogen fertiliser in the irrigation area of Northern Xinjiang, China.

The riverbed and riparian zone are the hotspots of nitrogen removal in rivers. Denitrification plays an important role in the process of nitrogen removal. In this study, sediments from the straight channel riverbed and point bars were examined using indoor culture and acetylene inhibition techniques. The primary focus was to investigate the differences in denitrification rates between these sediments. The secondary focus was on the effects of temperature and carbon-nitrogen (C/N) ratios on the denitrification process. The results showed that denitrification rates were higher in point bar sediments compared to those in the straight channel bed. Denitrification rates were also higher in the near water area of the point bar than in the near bank area. Denitrification rates at 30 °C were significantly higher than at 10 °C for each sediment group as well as in samples having carbon and nitrogen amendments. Notably, when the C/N ratio was 2.5, the denitrification rate for samples with carbon and nitrogen additions was significantly higher than for samples without them. On average, denitrification rates increased by 2.56 times, 2.73 times and 2.87 times for sediments from the straight channel, inner part of the point bar, and near bank of the point bar, respectively. At the same time, the number of denitrifying bacteria was found to be higher in the point bar than in the straight channel. These findings highlight the beneficial role of point bars in accelerating sediment denitrification rates and emphasize the potential for increasing nitrogen removal capacity in rivers by optimizing temperature and C/N ratios. Changing the diversity of riverbed geomorphology, temperature and C/N can effectively enhance the nitrogen removal capacity of river ecosystems.

The use of lignocellulosic residues, originating from sawdust, in composting sewage sludge for organic fertilizer production, is a practice of growing interest. However, few studies have explored the effect of the proportion of sawdust and sewage sludge raw materials on composting performance in the humification process. This study assessed the addition of sawdust in the sewage sludge composting process, regarding carbon content, presence of heavy metals, and humification of the organic compost. The experimental design employed was a randomized complete block design with five treatments featuring different proportions of organic residues to achieve C/N ratios between 30–1 (T1: 100% sewage sludge and 0% sawdust, T2: 86% sewage sludge and 14.0% sawdust, T3: 67% sewage sludge and 33% sawdust, T4: 55% sewage sludge and 45% sawdust, and T5: 46.5% sewage sludge and 53.5% sawdust) and five replications, totaling 25 experimental units. The addition of lignocellulosic residue in sewage sludge composting increased the levels of TOC and the C/N ratio, reduced the levels of pH, P, N, Na, Ba, and Cr, and did not interfere with the levels of K, Ca, Mg, S, CEC, labile carbon, and metals Fe, Zn, Cu, Mn, Ni, and Pb. The increase in the proportion of sawdust residue favored the degradation of aliphatic groups, increasing the presence of aromatic structures and reducing humification at the end of composting. The use of sawdust as a lignocellulosic residue in sewage sludge composting is a viable and efficient alternative to produce high-quality organomineral fertilizers. [ABSTRACT FROM AUTHOR]

The use of aerobic granular sludge (AGS) for wastewater treatment has emerged as a promising biotechnology. A sodium alginate nucleus (SAN) incorporated into the AGS system can enhance aerobic granulation. Two important parameters influencing AGS formation and stability are the organic loading rate (OLR) and C/N ratio. In this study, AGS containing the SAN was cultivated under different OLR and C/N ratios. Through morphological analysis, physicochemical properties, and water quality analysis, the effects of the OLR and C/N ratio on the rapid formation and performance of AGS containing the SAN were investigated. The results showed that the most suitable OLR and C/N ratio in the SAN system were 1.4–2.4 kg/(m3∙d) and 10–15, respectively. A recovery experiment of sodium alginate (SA) showed that the group that formed AGS generally had a higher recovery efficiency compared with the group that did not form granular sludge. This work explored the suitable granulation conditions of AGS containing the SAN, and the results provide a theoretical basis for future practical applications. The recycling of SA as presented in this study may broaden the application prospects of SA. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) generation during composting not only leads to losses of nitrogen (N) but also reduces the agronomic values and environmental benefits of composting. This study aimed to investigate the effect of the C/N ratio on N2O emissions and its underlying mechanisms at the genetic level during the composting of vegetable waste. The experiment was set up with three treatments, including low C/N treatment (LT, C/N = 18), middle C/N treatment (MT, C/N = 30), and high C/N treatment (HT, C/N = 50). The results showed that N2O emission was mainly concentrated in the cooling and maturation periods, and the cumulative N2O emissions decreased as the C/N ratio increased. Specifically, the cumulative N2O emission was 57,401 mg in LT, significantly higher than 2155 mg in MT and 1353 mg in HT. Lowering the C/N ratio led to increasing TN, NH4+-N, and NO3−-N contents throughout the composting process. All detected nitrification-related gene abundances in LT continued to increase during composting, significantly surpassing those in MT during the cooling period. By contrast, in HT, there was a slight increase in the abundance of detected nitrification-related genes but a significant decrease in the abundance of narG, napA, and norB genes in the thermophilic and cooling periods. The structural equation model revealed that hao and nosZ genes were vital in N2O emissions. In conclusion, increasing the C/N ratio effectively contributed to N2O reduction during vegetable waste composting. [ABSTRACT FROM AUTHOR]

Climate and land use changes are causing trees line to shift up into mountain meadows. The effect of this vegetation change on the partitioning of soil carbon (C) between the labile particulate organic matter (POM–C) and stable mineral-associated organic matter (MAOM–C) pools is poorly understood. Therefore, we assessed these C pools in a 10 cm topsoil layer along forest–meadow ecotones with different land uses (reserve and pasture) in the Northwest Caucasus of Russia using the size fractionation technique (POM 0.053–2.00 mm, MAOM < 0.053 mm). Potential drivers included the amount of C input from aboveground grass biomass (AGB) and forest litter (litter quantity) and their C/N ratios, aromatic compound content (litter quality), and soil texture. For both land uses, the POM–C pool showed no clear patterns of change along forest–meadow ecotones, while the MAOM–C pool increased steadily from meadow to forest. Regardless of land use, the POM–C/MAOM–C ratio decreased threefold from meadow to forest in line with decreasing grass AGB (R2 = 0.75 and 0.29 for reserve and pasture) and increasing clay content (R2 = 0.63 and 0.36 for reserve and pasture). In pastures, an additional negative relationship was found with respect to plant litter aromaticity (R2 = 0.48). Therefore, shifting the mountain tree line in temperate climates could have a positive effect on conserving soil C stocks by increasing the proportion of stable C pools. [ABSTRACT FROM AUTHOR]

THIS RESEARCH aims to study the degree and duration of the thermophilic phase by changing the available carbon source to reduce the period of composting within a fully equipped reactor with a controllable stirring and ventilation unit and its impact on the quality of the produced compost. The first stage analysis of raw materials used physically and chemically. Then determined the need for nitrogen supplements and the appropriate particle size of the nutrient. Initially, the experiment contained six treatments obtained by mixing agricultural plant residues (pepper and broccoli) with cow manure in different mixing ratios: 95:5, 90:10, 85:15, 60:40, 50:50 and 10:90 respectively. Then from the resulting data of the first experiment, the mixing ratios of 50:50 and 60:40 were chosen as the best ratios that showed the highest temperatures, then other parameters were added to them, which are (20 ml used oil and 20% compost as inoculum). The addition of used oil (50:50) resulted in the record of the highest temperature of 59°C and the thermophilic phase lasted for 5 days. However, with ratios (60:40) recorded 56°C and the thermophilic phase lasted for 4 days and the composting process was completed within 18 days. While when the inoculum was added with (50:50) ratios, the temperature reached 52.7°C and with (60:40) it reached 51°c and the compost was completed ripening after 25 days from the beginning of the experiment. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Bioprocess Engineering is the property of Chinese Journal of Bioprocess Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The elemental, isotopic, and molecular (biomarker) compositions of sedimentary organic matter help to evaluate conventional petroleum source rocks. The objectives of this overview article are to discuss commonly used organic geochemical indices for petroleum source rock evaluation, and analyze and synthesize such studies in the Indian Subcontinent. Since most of the fundamental analysis has been carried out in the European and North American Continents, this study covers the gap in the Indian Subcontinent. The organic geochemical indices reviewed are total organic carbon (TOC), Rock-Eval pyrolysis, C/N ratio, carbon isotopic composition, molecule/biomarkers (e.g., n-alkane/aliphatic hydrocarbon, polycyclic aromatic hydrocarbon) which are used for qualitative and quantitative analysis of source rock composition. This study also evaluates the lithostratigraphic characteristics of the source rocks in the Mannar Basin of the Indian Subcontinent. In conclusion, the Mannar petroleum source rocks show Type III and Type II–III dominated gas and oil-gas prone kerogen with fair to good source rock potential. A comparison of organic geochemical indices with their geologic setting would improve interpretations of petroleum source rock characteristics in the Indian Subcontinent. [ABSTRACT FROM AUTHOR]

Peatland restoration usually aims at restarting the peatlands' function to store carbon within peat. The soil properties of the near-surface peat can give a first understanding of this process. Therefore, we sampled pH value, total organic carbon content (TOC), total nitrogen content (TN), C/N ratio as well as dry bulk density (BD), and describe the structure of near-surface peats in six restored fens in North-East Germany before (2002-2004) and after (2019-2021) restoration. Before restoration, the study sites showed peat degradation to various extents in their near-surface peats. pH values remained relatively stable over time. Comparing the degraded peat horizons, TOC increased significantly in four study sites, ranging from 35.7% to 47.8% in 2002-2004 and from 42.5% to 54.0% in 2019-2021. TN varied from 1.5% to 3.5% in 2002-2004 and from 1.8% to 3.2% in 2019-2021, but changes were only significant in one site, showing a slight decrease. In three sites, the increase in C/N ratio was significant, indicating lower nutrient availability. BD ranged from 0.08 to 0.48 g/cm3 in 2002-2004 and from 0.10 to 0.16 g/cm³ in 2019-2021, decreasing significantly in four sites. The structure of the degraded peat horizons changed after restoration to a more homogenous, sludge mass with larger re-aggregates. In three sites, new peat moss peat layers above the degraded soil horizon were present in 2019-2021, with a mean thickness of 6.8 to 36.1 cm. The structure was comparable to typical, slightly decomposed peat moss peat. Our findings suggest that within about 17 years after fen restoration, and thereby a water table rise close to surface, TOC of the near-surface peats increased to values that are typical for undisturbed peatlands. This indicates that restoration can lead to the re-establishment of peatlands as potential carbon sinks, with TOC within the near-surface peat as one key factor in this process. Further, we assume that the decrease in nutrient availability, decrease of BD, and new, undisturbed peat layers can favor the establishment of mire-specific biodiversity and support ecosystem services similar to near-natural mires. [ABSTRACT FROM AUTHOR]

The relationship between the degree of decay, carbon dynamics, and nutrients of coarse woody debris (CWD) were examined in the experimental forest of Kheirudkenar – Nowshahr as a part of Hyrcanian forests in Northern Iran. CWD (snag and log) with an average middle diameter more than 7.5 cm was recorded in 50 ha. For snag CWD, species type, diameter at the breast height and height, while for log CWD, species type, the average diameter and their length were determined and recorded. In the case of non-circular CWD cross-sections especially in the higher decay stages, diameter was determined by tape. All CWD were categorized in three diameter classes and the degree of their decay (snag and log) was determined. The CWD nutrients examined throughout taking a piece from each CWD and analysing them in the laboratory (60 specimens). The C/N ratio of CWD was obtained separately for diameter classes and degrees of decay. All data were tested for probability of fit to normal distribution. To identify the most influential gradients, principal component analysis (PCA) was applied. The nutrients in the trunk CWD in different diameter classes and degrees of decay showed that in most cases, there is a significant difference between them. The results of the C/N ratio of the total trunk of CWD showed that this ratio decreases by elevating the degree of decay and by upraising the diameter classes of CWD. The degrees of decay of CWD were majority related to N, C/N ratio, C and K respectively. This research demonstrated that the nitrogen and carbon concentrations among the decay classes and species type of CWD should be considered. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Taiwan Agricultural Research is the property of Taiwan Agricultural Research Institute, Council of Agriculture, Executive Yuan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aimed to enhance the nutrient balance of municipal solid waste (MSW), characterized by a high carbon-to-nitrogen (C/N) ratio, which is a critical factor in the anaerobic digestion process. The investigation involved the addition of MSW, which is rich in carbon content, to food waste (FW) with high nitrogen content. The goal was to determine an optimal co-substrate mixing ratio of MSW and FW for anaerobic co-digestion at mesophilic temperatures, aiming to improve process stability and performance to achieve higher biogas yield. The co-digestion experiments encompassed five mixing ratios of MSW and FW with C/N ratios of 20, 25, 30, 35, and 40 under mesophilic conditions in a laboratory. The results indicated that the highest specific biogas yield, reaching 827 L/kg VS, was attained when the co-substrate feedstock had a balanced C/N ratio of 20, surpassing the 520 L/kg vs. obtained from MSW digestion alone. As the proportion of MSW increased in the co-substrate mixing feedstock, the biogas production rate decreased. Additionally, the study explored the optimal substrate-to-inoculum (S/I) ratio, focusing on the co-substrate feedstock with a C/N ratio of 20. Four S/I ratios (0.5, 1.0, 1.5, and 2.0) were examined, revealing that the highest specific biogas yield, at 642 L/kg VS, occurred at an S/I ratio of 0.5. An accumulation in volatile fatty acids (VFAs) was observed at higher S/I ratios, attributed to the lower abundance of inoculum microorganisms in the anaerobic digestion process. Overall, the findings suggested that the optimum C/N ratio for co-digestion of MSW and FW falls within the range of 20–25/1, while the preferred S/I ratio is 0.5. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel ternary mixture of inexpensive and nutrient-rich agro-substrates comprising groundnut de-oiled cake, corn gluten meal, and soybean meal has been explored to enhance the L-asparaginase production in solid-state fermentation. To achieve the aim, a hybrid strategy was implemented by utilizing a combination of a mixture design and artificial neural networks. The study initiated with the judicious selection of the agro-substrates based on their low C/N content in comparison to the control using the CHNS elemental analysis. The mixture composition of soybean meal (49.0%), groundnut de-oiled cake (31.5%), and corn gluten meal (19.5%) were found optimum using the simplex lattice mixture design. The agro-industrial substrates mix revealed synergistic effects on the L-asparaginase production than either of the substrates alone. The maximum L-asparaginase activity of 141.45 ± 5.24 IU/gds was observed under the physical process conditions of 70% moisture content, autoclaving period of 30 min and 6.0 pH by adopting the machine learning–derived artificial neural network (ANN) methodology. The ANN modeling showed excellent prediction ability with a low mean squared error of 0.7, a low root mean squared error of 0.84, and a high value of 0.99 for regression coefficient. Moisture content (%) was assessed to be the most sensitive process parameter in the global sensitivity analysis. The net outcome from the two sequential optimization designs is the selection of the ideal mixture composition followed by the optimum physical process parameters. The application of the enzyme demonstrated significant cytotoxicity against leukemia cell line and therefore exhibited an anti-cancer effect. The present study reports a novel mixture combination and methodology that can be used to lower the cost and enhance the production of L-asparaginase using an agro-industrial substrate mixture. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) of algal-bacterial biomass grown on wastewater has been used successfully for bio-methane production. However, challenges with AD of microalgae include inhibition due to accumulation of free ammonia (FA) and volatile fatty acids (VFAs), alkalinity depletion, and/or pH outside optimal values. In this study, algal-bacterial biomass was cultured on high-strength wastewater and then co-digested with sugarcane bagasse, an agricultural waste product that is widely available in tropical regions of the world. Biochemical methane potential (BMP) assays were set up at approximately 2% solids content with varying ratios of algal-bacterial biomass and sugarcane bagasse and varying substrate to inoculum ratios (S/I). Although methane content of biogas was similar in all digestion sets (61–67%), co-digestion sets with algae and bagasse produced higher methane yields (145 and 101 mL CH4/g VS) than algae alone (61 and 82 mL CH4/g VS) or bagasse alone (74 mL CH4/g VS). A significant correlation (r2 = 0.88, p = 0.012) was observed between algal-bacterial biomass content of the substrate and total gas production and therefore methane yield. Environmental conditions, including pH, alkalinity, total ammonia nitrogen (TAN), and VFA concentrations, were in the favorable range in all BMPs. However, co-digestion BMPs had greater initial release of COD, VFA, and TAN and greater VS reduction, indicating enhanced biodegradability of the substrates. Additional research is needed on the potential for using waste resources, such as wastewater and agricultural residuals, for biogas production in tropical regions. [ABSTRACT FROM AUTHOR]

Secondary sexual dimorphism (SSD) in flowering plants is expressed by sexual differences of characters that are not directly related to gamete production. The leaf C/N ratio, photosynthetic traits or clonal responses have never been studied in relation to SSD in yerba‐mate. It was hypothesized that leaf and plant photosynthesis are higher in female than in male individuals because females must supply photoassimilates to compensate for the additional reproductive investments of SSD in biomass. Here, we investigated how two contrasting light environments (monoculture—MO and agroforestry—AFS) and plant genders change leaf and plant photosynthesis, plant architecture, leaf and branch biomass production and C and N investments of two male and two female clones. To model the 3D yerba‐mate structure, virtual trees were constructed using measurements of plant morphology using VPlant modelling software. The light‐response curves of leaf CO2 assimilation were used to model instantaneous leaf and daily plant photosynthesis. Photosynthetic traits derived from light‐response curves did not differ between MO and AFS. Some architectural traits were segregated sexually only in MO, while some physiological ones only in AFS. Leaf photosynthesis was higher in females than in males in AFS over a large part of the diurnal cycle, but SSD was not expressed in carbon gains at plant or daily scales. Leaf C/N ratio was higher in MO than in AFS, indicating MO as an ecosystem with higher degree of environmental degradation. Female clones had leaves with lower C/N ratio than males in both systems, relating to higher leaf photosynthesis on an area basis in females. SSD expressed in leaf photosynthesis over a large part of the diurnal cycle in AFS was not observed in carbon gains at plant or daily scales, indicating that the integration of physiology and architecture equalized the gender specificities. The insensitivity of photosynthetic traits derived from light‐response curves indicated acclimation of yerba‐mate leaves to a wide range of incoming light. [ABSTRACT FROM AUTHOR]

Tofu wastewater is a nitrogen-rich wastewater type with a high concentration of organic contents. To enhance the digestion rate of tofu wastewater in an anaerobic bioreactor, water hyacinth was tested as an additional substrate. Water hyacinth is a dangerous weed with a high carbon-nitrogen ratio (C/N) of about 30-35. Substrate combination was intentionally used in this study to raise the C/N of wastewater. This study aims to evaluate the digestion rate of a bioreactor qualitatively based on experimental data to determine the biokinetic constants of the anaerobic bioreactor quantitatively based on microbial growth data, substrate degradation, and methane (CH4) production. MATLAB was used as software to run mathematical modeling. The anaerobic bioreactor was designed and equipped with a circulation pump to maintain the homogeneity of the substrate and was completed with a biogas collector. Seeding and acclimatization were carried out before the main experiment started. Using a combination substrate of tofu wastewater and water hyacinth with a 5:3 volume ratio, the bioreactor was run at 20 days of hydraulic retention time (HRT) at room temperature. The bioreactor was able to remove 92.8% of chemical oxygen demand (COD) concentration and produced biogas with the highest CH4 concentration of 56.9%. The obtained kinetic constants indicate that, in comparison with similar studies of anaerobic digestion of the low C/N wastewater, the addition of water hyacinth resulted in better performance of the bioreactor with the correlation of microbial growth rate (?m), substrate degradation (YX/CCOD) and CH4 production (YCCH4/X) with the consecutive values of 0.65/day, 0.64 mg cells/mg COD, and 0.62 mg CH4/mg cells. An appropriate ratio of water hyacinth as the high carbon source and nitrogen-rich tofu wastewater is recommended to obtain the optimum ratio of carbon to nitrogen and result in a higher percentage of methane formation. ABSTRAK: Air sisa tauhu ialah air sisa yang kaya dengan nitrogen dengan kepekatan kandungan organik yang tinggi. Bagi meningkatkan kadar penghadaman air sisa tauhu dalam bioreaktor anaerobik, keladi bunting diuji sebagai substrat tambahan. Keladi bunting merupakan rumpai berbahaya dengan nisbah karbon nitrogen (C/N) yang tinggi iaitu kira-kira 30-35. Gabungan substrat sengaja digunakan dalam kajian ini bagi menaikkan C/N air sisa. Kajian ini bertujuan bagi menilai kadar pencernaan bioreaktor secara kualitatif berdasarkan data eksperimen dan menentukan pemalar biokinetik bioreaktor anaerobik secara kuantitatif berdasarkan data pertumbuhan mikrob, degradasi substrat, dan pengeluaran metana (CH4). MATLAB digunakan sebagai perisian pemodelan matematik. Bioreaktor anaerobik direka bentuk dan dilengkapi dengan pam edaran bagi mengekalkan kehomogenan substrat dan dilengkapkan dengan pengumpul biogas. Penyemaian dan penyesuaiikliman telah dijalankan sebelum eksperimen utama bermula. Substrat gabungan air sisa tauhu dan keladi bunting digunakan dengan nisbah isipadu 5:3. Bioreaktor dijalankan selama 20 hari iaitu masa pengekalan hidraulik (HRT) pada suhu bilik. Bioreaktor tersebut mampu mengasingkan 92.8% kepekatan permintaan oksigen kimia (COD) dan menghasilkan biogas dengan kepekatan CH4 tertinggi sebanyak 56.9%. Pemalar kinetik yang diperoleh menunjukkan bahawa, berbanding dengan kajian serupa tentang pencernaan anaerobik air sisa C/N rendah, penambahan keladi bunting menghasilkan prestasi bioreaktor yang lebih baik dengan korelasi kadar pertumbuhan mikrob (?m), degradasi substrat (YX/CCOD) dan penghasilan CH4 (YCCH4/X) dengan nilai masing-masing 0.65/hari, 0.64 mg sel/mg COD, dan 0.62 mg CH4/mg sel. Nisbah keladi bunting yang sesuai sebagai sumber karbon tinggi dan air sisa tauhu yang kaya dengan nitrogen disyorkan agar mendapatkan nisbah optimum karbon kepada nitrogen dan ini menghasilkan peratusan pembentukan metana yang lebih tinggi.

Membrane aerated biofilm reactor （MABR） effectively combines biofilm technology and membrane separation technology，which has great potential in wastewater denitrification. This paper focuses on the stability and nitrogen removal performance of MABR，which is used to treat soybean processing wastewater and simulated domestic wastewater. The results showed that when HRT was 12 h，aeration pressure was 10 kPa and C/N ratio was 5，MABR had the best treatment effect on simulated domestic sewage，and the average removal rates of COD，ammonia nitrogen and TN were 92.0%，86.5% and 83.3% respectively. When HRT was 8 h and aeration pressure was 10 kPa，MABR had the best treatment effect on soybean processing wastewater. The volume loads of COD，ammonia nitrogen， TN were 1 320，125.5，184 g/（m3·d） respectively，and the average removal rate had reached 84.2%，81.5%， 79.7% respectively，which was superior to the traditional biofilm method for nitrogen removal.

The livestock sector's waste is a potential raw material for producing biogas because it is abundantly available. This experiment aimed to understand the potential of two types of livestock waste to produce biogas. The two sources of raw material were mixed with different variations. The results showed that the volume of fermentation gas produced from livestock waste varied depending on the type and composition of the raw material used. Mixing was done to determine the best variation in producing biogas from chicken litter and cow manure. The volume ratio of litter to cow manure used was (0%:100%), (25%:75%), (50%:50%), (75%:25%), (and 100%:0%), with a total volume of 2 liters. In addition, 10% of EM-4 (effective microorganism) was added to the mixture of livestock waste that had previously been given 2 liters of water. The waste mixture was then fermented for 30 days. The fermentation process was carried out under mesophilic conditions at room temperature and pressure. This study showed that the higher the concentration of chicken litter in the mixture, the higher the carbon-to-nitrogen (C/N) ratio value. On the other hand, if there is a higher composition of cow manure in the mixture, the substrate pH value will be higher. Furthermore, a 50%:50% composition of chicken litter and cow manure produced a high volume of biogas. Similarly, the biogas formation rate in this composition showed the best performance. These results prove that the balance of carbon and nitrogen composition, temperature, and substrate acidity significantly affect biogas production.

Composting degradable organic matters with chemical fertilizers produces stable material with the aid of organisms and makes nutrients readily available to plants. A field study was carried out for incorporation of the urea and KOH treatments on composting fresh cattle manure, wheat straw, sawdust, and dried leaves to evaluate the decomposition rate during four months. The mineralization of the organic wastes as increased in microbial biomass carbon (MBC) and organic matter (OM) loss was higher in urea treatments, in contrast with KOH treatments which need more time for optimum decomposition. Laccase activity reduced in the manure but increased in other organic wastes and in the urea treatments. Water-soluble carbon (WSC) decreased in all organic wastes, particularly in urea-treated manure. The fluctuation of pH and electrical conductivity (EC) were observed for four months but increased at the end of the experiment. Total organic carbon (TOC) reduced, and total nitrogen (TN) has risen, especially in the presence of urea treatments; so, the C/N ratio significantly decreased and the trend of composting progressed overtime. Insufficient technical planning in composting has led to changed approaches to increase elements availability with the management of existing plantations. The successive applications of urea were observed to enhance the rate of organic wastes decomposition than KOH treatments. This study further recommends application of urea and KOH with degradable organic materials in which this method should be improved with the ability to mineralize nutrients rapidly, which could make them advantageous to crop growth. [ABSTRACT FROM AUTHOR]

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This study designed surface flow constructed wetlands (SFCWs) with Myriophyllum aquaticum (M. aquaticum) to evaluate how different influent C/N ratios (0:1 (C0N), 5:1 (C5N), 10:1 (C10N), and 15:1 (C15N)) affect pollutant removal, greenhouse gas (GHG) emissions, and microbial communities. The results showed that effluent ammonia nitrogen ( N H 4 + -N), nitrate nitrogen ( N O 3 − -N), and total nitrogen (TN) concentrations decreased, but effluent chemical oxygen demand (COD) concentration increased with increasing influent C/N ratios. The highest removal rates of TN (73.17%) and COD (74.56%) were observed with C5N. Regarding GHG emissions, a few changes in CO2 fluxes were caused by the influent C/N ratio, whereas CH4 fluxes obviously increased with the increasing influent C/N ratio. The highest N2O emission occurred with C0N (211.03 ± 44.38 mg-N·m−2·h−1), decreasing significantly with higher C/N ratios. High-throughput sequencing revealed that different influent C/N ratios directly influenced the microbial distribution and composition related to CH4 and N2O metabolism in SFCWs. The highest abundance (46.24%) of denitrifying bacteria (DNB) was observed with C5N, which helped to achieve efficient nitrogen removal with a simultaneous reduction in N2O emissions. Methanogen abundance rose with higher C/N ratios, whereas methanotrophs peaked under C5N and C10N conditions. Additionally, the random forest model identified influent C/N ratio and Rhodopseudomonas as primary factors influencing CH4 and N2O emissions, respectively. This highlights the importance of the influent C/N ratio in regulating both pollutant removal and GHG emissions in constructed wetlands. [ABSTRACT FROM AUTHOR]