Highest NH3-N Research Articles

Nutrient recovery from anaerobic digester supernatant using a fluidized-bed reactor

This study investigated nutrient recovery by struvite precipitation from anaerobic digester supernatant containing nitrogen and phosphorus at high concentrations using a fluidized-bed reactor. In the first phase, hydraulic retention time (HRT) in the system was reduced from 15 min to 2.5 min at molar Mg2+/NH4+/PO43− ratio of 1.5/16.6/1. No significant differences were detected and struvite could be precipitated at high performances even at an HRT of 2.5 min. In the second stage, the impact of Mg/P molar ratio on struvite precipitation performance was evaluated at the molar ratios of 1/1, 1.5/1, 2/1 and 2.5 min HRT. The highest NH4-N and PO4-P precipitation performances were around 38 % and 99.7 %, respectively, at an Mg/P molar ratio of 2. In the last stage, the impact of volatile fatty acid presence on the system performance was investigated by adding 1000 mg/L acetate to the synthetic wastewater at an Mg/P molar ratio of 1.5/1. Observing above 99 % PO4-P removal efficiency both in the presence and absence of acetate confirmed that VFA may not have adverse impact on struvite precipitation performance. According to XRD results, struvite precipitates had a crystal structure with only a small amount of impurities.

Environmental Remediation Potential of Ferrous Sulfate Waste as an Eco-Friendly Coagulant for the Removal of NH3-N and COD from the Rubber Processing Effluent

The present study was conducted to determine the potential of utilizing the FeSO4·7H2O waste from the titanium manufacturing industry as an effective coagulant for treating industrial effluent. In this study, the secondary rubber processing effluent (SRPE) was treated using ferrous sulfate (FeSO4·7H2O) waste from the titanium oxide manufacturing industry. The FeSO4·7H2O waste coagulation efficiency was evaluated on the elimination of ammoniacal nitrogen (NH3-N) and chemical oxygen demand (COD) from SRPE. The central composite design (CCD) of experiments was employed to design the coagulation experiments with varying coagulation time, coagulant doses, and temperature. The coagulation experiments were optimized on the optimal elimination of NH3-N and COD using response surface methodology (RSM). Results showed that coagulant doses and temperature significantly influenced NH3-N and COD elimination from SRPE. The highest NH3-N and COD removal obtained were 98.19% and 93.86%, respectively, at the optimized coagulation experimental conditions of coagulation time 70 min, coagulant doses 900 mg/L, and temperature 62 °C. The residual NH3-N and COD in treated SPRE were found below the specified industrial effluent discharge limits set by DoE, Malaysia. Additionally, the sludge generated after coagulation of SRPE contains essential plant nutrients. The present study’s finding showed that FeSO4·7H2O waste generated as an industrial byproduct in a titanium oxide manufacturing industry could be utilized as an eco-friendly coagulant in treating industrial effluent.

Nitrogen availability under conventional and conservation tillage in semiarid Inceptisol

The present experiment was conducted to study the spatio-temporal variation of available nitrogen fraction in cotton (Gossypium hirsutum L.) in conservation agricultural based long term experiment (since 2010) during 2019-20. The treatment comprises two distinct practices, i.e. conventional tillage (CT) and zero tillage (ZT). Under ZT, permanent narrow bed without (PNB) and with residue of previous crops (PNB+R); permanent broad bed without (PBB) and with residues (PBB+R); flat bed (FB) and FB with residues (FB+R). Soil samples were collected (0-15 and 15-30 cm) at pre-flowering, flowering, boll formation and harvest stages. Adoption of CA practices increased the NH4-N, NO3-N and mineral-N fractions of nitrogen at different crop growth stages. Highest NH4-N, NO3-N and mineral-N were recorded at flowering and boll formation stage respectively. The effect of crop residue retention and crop establishment methods on available N fractions was prominent up to 15 cm soil depth. Crop residue retained plots recorded significantly higher N fraction compared to respective without residue and CT plots. Residue retained plots of FB, PBB, PNB recorded 50, 25 and 36% higher NO3-N concentration as compared to respective without residues plots at pre-flowering stage. At flowering stage, maximum NH4-N was recorded in PBB+R (17.9 mg/kg) and FB+R plots (17.5 mg/kg), which was approximately 68 and 16% higher over CT and PNB+R plots. The results revealed that zero tillage together with PBB+R could be a viable option over conventional practice for maintaining nitrogen availability to plants under cotton-wheat (Triticum aestivum L.) cropping system in semiarid climate.

Agrowastes Potentials in Releasing Soil form of Nitrogen

A laboratory incubation study to determine the decomposition rate of Sunflower (SF), Gliricidia sepium (GL), Kola Pod Husk (KPH), and Cocoa Pod Husk (CPH) on soil forms of nitrogen was carried out at the Department of Agricultural Science, Adeyemi College of Education, Ondo South-Western Nigeria. The soil sample was collected from the farmers’ field in Ondo. The soil was air-dried and sieved through a 2mm diameter laboratory sieve. 200g of the soil samples were weighed into cups and 1g of each CPH, SF, GL and KPH was added. The treatments were replicated five times to give 45 cups of soil samples and arranged on a Completely Randomised Design. The cups were covered with absorbents. The treatments were analysed 30, 60 and 90 days to determine total N, NO3-N and NH4-N using destructive analytical method. Compared with control, all the treatments significantly increased total N and NO3-N while SF and GL significantly increased (p <0.05) NH4-N at 30 days of incubation. All the treatments significantly increased (p <0.05) total N, NH4-N and NO3-N at 60 and 90 days. Cocoa Pod Husk had the highest increase in total N while KPH recorded the highest NH4-N and NO3-N. Cocoa Pod Husk (CPH), KPH, GL and SF could be used to increase soil forms of N for optimum crop production in Ondo, South-Western Nigeria.

Intensified nitrogen removal of constructed wetland by novel integration of high rate algal pond biotechnology

High rate algal pond (HRAP) was combined with constructed wetland (CW) to intensify nitrogen removal through optimizing nitrification and denitrification. Nitrification and denitrification process mainly depends on the oxygen content and carbon source level in CWs. Algal biomass was enriched in HRAP, and dissolved oxygen (DO) concentration was increased via photosynthesis. Algal debris increased COD as degradable bioresource. The results showed that HRAP-CW hybrid systems effectively promoted the nitrogen removal performance due to rich DO and COD. The extension of hydraulic retention time in HRAP significantly improved NH4-N and TN removals by 10.9% and 11.1% in hybrid systems, respectively. The highest NH4-N and TN removals in hybrid systems respectively reached 67.2% and 63.5%, which were significantly higher than those in single CW. The study suggested that the hybrid system had the application potentials in nitrogen removal from wastewater.

Regional optimal allocation for reducing waste loads via artificial neural network and particle swarm optimization: a case study of ammonia nitrogen in Harbin, northeast China.

Cutting external waste loads can improve water quality. Allocation for reducing waste loads should consider changing variables, such as river flows and pollutant emissions. A particle swarm optimization (PSO) method and coupling artificial neural network (ANN) models have been applied to optimize reduction rates of ammonia nitrogen (NH3-N) loads from sewage outlets in Harbin, northeast China. For the planned water quality functional section (WQFS), the NH3-N concentration is related to emitted pollutant loads and can be well predicted by ANN linkage models. Further, NH3-N load reduction rates of all outlets are optimized by PSO with the water quality standard target. The highest NH3-N concentrations occur in January and February, a typical low-flow period in Harbin. The results delivered optimum NH3-N reduction rates for the five outlets, for January and February 2011. All predicted NH3-N concentrations after the reduction meet the water quality standard. The results indicate that the outlet with the highest NH3-N load has the biggest reduction rate in each WQFS, and outlets in the WQFS with higher background NH3-N concentrations need to cut more NH3-N loads. Decision-makers should not only focus on the outlet with the highest NH3-N emission load, but also ensure that the NH3-N concentration of upper WQFS meets the water quality goal.

Green Manure and N Fertilizer Rate Effects on Cassava and Sweet Corn Sequential Cropping in a Sandy Typic Plinthustult

Appropriate N fertilizer rate for cassava and sweet corn sequential cropping grown after different green manures was investigated on a Typic Plinthustult in the tropical climate of Thailand. Split-plot experimental design was used, and three treatments, ruzi grass (Brachiaria ruziziensis), sun hemp (Crotalaria juncea), and local weeds (e.g., jungle rice (Echinochloa colana), crabgrass (Digitaria biformis), and coat button (Tridox procumbens)) grown as green manure, were chosen as the main plot. Nitrogen fertilizer levels, 0, 0.5, 1.0, and 1.5 times the rates recommended for cassava (94 kg N ha) and sweet corn (191 kg N ha), were tested as subplots. Comparing average yield over all fertilizer treatments, ruzi grass statistically had the highest dry biomass and the lowest N content and released the highest NH4-N but gave the lowest tuber yield and peeled sweet corn grown after cassava. Incorporation of sun hemp, having the highest N content and the highest NO3-N released to the soil, significantly gave the highest yields of cassava (25.1 t ha) and peeled sweet corn (3.5 t ha) and aboveground biomass. Incorporated sun hemp and N applied at recommended rates significantly gave the highest cassava fresh tuber yield of 27.2 t ha. Either crop grown sequentially showed no response to N fertilizer rates except for cassava starch content that significantly decreased with increasing N fertilizer rates. In a separate experiment, sun hemp decomposition resulted in a slightly higher available N production than did ruzi grass. The sun hemp decomposition was greater in most weeks during the experiment.

Combined Effect of Cattle Dung and Urea Fertilizer on Organic Carbon, Forms of Nitrogen and Available Phosphorus in Selected Nigerian Soils

Incubation experiment was conducted on four soil types in Nigeria using cattle dung (CD) at the rate -1 -1 of 2.5g/kg soil ( 5 t ha ), Urea fertilizer at the rate of 0.1g/kg soil ( 200 kg ha ) and cattle dung -1 (2.5g/kg soil) combined with Urea 0.05g/kg soil (100 kg ha ) as treatments. The objective of the experiment was to compare the rate of OC, NH 4 – N, NO3 – N and available P release on soils selected from different agro ecological zones of Nigeria. Ten soil samples were collected and bulked from each of the sandy clay, sandy loam, sandy clay loam and loamy sand soils from three different locations within each soil type. The soils were arranged on completely randomized design in laboratory for 60 days. All the treatments reacted differently in each of the soil type in relation to OC, total N, NH4 – N, NO3 – N and available P. In sandy clay and sandy loam soils, all the treatments significantly increased (p < 0.05) OC, total N, NH4 – N, NO3 – N and available P except OC in sandy loam compared with control. In sandy clay loam and loamy sand soils, all the treatments significantly increased (p< 0.05) NH4 – N, NO3 – N and available P. Among all the treatments, CD had the highest OC in all the soil textural classes,, urea had the highest NH4-N and NO3-N while CD + urea had the highest available P (except sandy clay). Cow dung had the highest P in sandy clay. Sand loam and sandy clay loam had highest total N but urea recorded highest value of N in sandy clay while urea+CD mineralized equal amount of total N

Nitrogen Leaching from Saybrook Soil Amended with Biosolid and Polyacrylamide

In this study, Nitrogen leaching following surface application of biosolid with and without polyacrylamide (PAM) coating was investigated using soil column experiments. Three treatments including bare soil (C), a commercially available biosolid (BS) and PAM coated biosolid (PAM + BS), were applied to manually packed (bulk density: 1.3 g·cm-3) growth chamber soil columns (GC columns: 5 cm diameter by 40 cm long) and greenhouse soil columns (GH columns: 15 cm diameter by 40 cm long). The application rates for BS and PAM + BS were 729 and 740 kg/ha, respectively. The GC columns were incubated for 60 days in a dark chamber at 25℃ and no crop was grown in the columns. The GH columns were incubated for 60 days in a greenhouse and Ryegrass (seed rate: 252 kg/ha) was grown in these columns under 16 h daylight and at about 25℃. The columns were irrigated weekly using 270 mL DI-water for GC columns and 850 mL for GH columns and leachate was analyzed for Ammonium (NH4-N), Nitrate (NO3-N) and total Nitrogen (TN). The GH column experiments were repeated with three times greater biosolid application rate (2187 kg/ha) while keeping the PAM and Ryegrass seed rate constant. The leachate volume and NH4-N, NO3-N and TN concentration/load were not significantly different among the treatments for the GH columns but were significantly different during the incubation period. The same was true for GC columns with the exception of NO3-N and TN concentration/load which, overall, were higher for the BS and PAM + BS treatments than for the C treatment. In the beginning of the incubation, the leachate from all treatments (GC and GH) contained the highest NH4-N concentrations (>USEPA target level: 0.1 mg/L) and decreased, in some cases rapidly, to near zero. The NO3-N concentrations were highest in the middle of the incubation and greater than the USEPA target level (10 mg/L). The NO3-N concentrations were lower for cropped GH columns compared to GC columns due to NO3-N uptake by plants. The three fold increase in biosolid application rate did not increase NH4-N concentrations in leachate but did increase NO3-N and TN concentrations/loads in leachate on average 2.5 to 2.7 times. The non-significant differences among treatment means for NH4-N, NO3-N and TN concentrations/loads for the GH columns suggest that land application of biosolid (with or without PAM) to cropped silt loam landscapes at the rates considered may be safe within the context of groundwater pollution.

NUTRIENT CONCENTRATIONS IN SOIL SOLUTIONS FOR MUSKMELONS AS INFLUENCED BY FERTILIZER TREATMENT

A study was made to investigate the effects of liming and N source fertilization on soil acidity, nutrient uptake an yield of muskmelon on a Princeton loamy-sand (fine sandy, mixed, mesic, type Hapludalf) at Southwest Purdue Agricultural Center, Vincennes, IN. The experiment consisted of lime and no lime treatments with five N treatments of 0 N, 50 kg·ha-1 N as urea and 100 kg·ha-1 N as urea, NH4NO3, and (NH4) SO4. The unlimed soil tested pH 4.6, 4.2 and 4.1 and the limed soil was pH 5.5, 5.6 and 5.2 with 100 kg N·ha-1 as urea, NH4NO3 and (NH4) SO4, respectively. With NH4NO3 the NO3-N declined from 268 ppm on 6/1 to 64 ppm on 7/7 in the saturation extract (SE). Highest NH4-N was from (NH4)2SO4 followed by NH3NO4 and urea. The NH4-N concentration from (NH4)2SO4 in the SE decreased from 152 ppm to 19 ppm during the season on unlimited soil and from 56 ppm to 8 in the SE decreased from 152 ppm on limed soil. Symptoms of Mn toxicity in the leaves became apparent on unlimed plots 7 weeks after transplanting. As the rate of N increased in the range of 0, 50 and 100 kg·ha-1 from urea the Mn contents were 372,459 and 607 ppm respectively. The muskmelon fruit yield increase due to 100 kg N·ha-1 was 13279 kg·ha-1, 12161 kg·ha-1 and 8502 kg·ha-1 for ureas, NH4NO3 and (NH4)2SO4 respectively.