Total Kjeldahl Nitrogen Concentrations Research Articles

Biodegradation of sugarcane trash into substrates of utilizable products using lignocellulolytic microorganisms

Biodegradation of sugarcane trash was conducted using lignocellulolytic microorganisms, Bacillus subtilis (MW715021) and Schizophyllum commune (MW720154) strains. Throughout the biodegradation process, various physicochemical, biochemical, and microbial parameters were monitored. The weight, organic carbon, and C:N ratio of the sugarcane residue progressively decreased from 20 to 120 days of incubation. Among different treatments, T7 (Sugarcane trash + Bacillus subtilis + Schizophyllum commune) exhibited significantly the lowest weight, organic carbon, and C:N ratio of 61.60 g, 17.85%, and 13.02, respectively. The pH of the substrate decreased slightly at the initial period of biodegradation then it increased slightly and became stable at near about neutral pH. The Electrical Conductivity (EC) of the substrate was increased with the advancement of incubation periods. The Total Kjeldahl Nitrogen (TKN) content of the substrate increased with the duration of incubation. A higher TKN content of 1.37% was recorded in T7 on 120 days of incubation. The nutrient content (P2O5, K2O, Fe, Mn, Zn, and Cu) of the substrate was increased with the advancement of the decomposition period. The cellulose and lignin content was reduced from 40.78 to 21.54 % to 23.16 and 10.84 %, respectively in T7. Lignocellulolytic enzymes i.e. cellulase, laccase, lignin peroxidase, and manganese peroxidase were increased at initial degradation periods up to 60 days then it declined at a later stage of biodegradation. The microbial population increased with incubation periods up to 60 days then after it was declined at a later stage of biodegradation.

Soil properties following borrow pit reclamation with insufficient topsoil amended with peat and biochar

AbstractDisturbed sites, such as borrow pits and oil and natural gas well sites, require reclamation to restore and sustain levels of productivity similar to those prior to the disturbance. However, salvaged topsoil at many sites is often insufficient to meet the 80% topsoil replacement depth (TRD80) required for successful reclamation in western Canada. This 5‐year study evaluated soil responses to 50% topsoil replacement depth without organic amendment (TRD50) or amended with either peat (PTRD50) or biochar (BTRD50), relative to the TRD80 treatment (Control), following borrow pit reclamation at a disturbed boreal site near Cold Lake, Alberta, Canada. Amendments were applied once at rates calculated to raise the soil organic carbon (SOC) content in the TRD50 soil to a level equal to that in the TRD80 treatment. Results showed a 143%, 87%, and 116% increase in total Kjeldahl nitrogen concentration in the PTRD50 relative to the TRD80, TRD50, and BTRD50 treatments, respectively, while soil potassium (K) concentration was significantly greater for BTRD50 than PTRD50. Peat and biochar significantly increased SOC concentrations by 83% and 88%, respectively, relative to the mean of TRD80 and TRD50 treatments. Our results show that peat and biochar can improve soil properties of disturbed boreal sites reclaimed with insufficient salvaged topsoil to a level suitable for successful reclamation. This has important implications on the reclamation of a multitude of disturbed sites, in Canada and globally, that have insufficient volumes of salvaged topsoil needed for successful reclamation.

Two-stage (liquid-solid) anaerobic mono-digestion of ammonia-rich chicken manure at low-temperature: Operational strategy and techno-economic assessment

This study investigated mono-digestion of ammonia-rich chicken manure (CM) in a high-solids anaerobic-digester (HSAD) at low-temperature (20±1°C) adopting the recirculation-percolation mode of operation using liquid-inoculum. HSAD was operated for about 282 days in batch-runs under different organic loading rates (4.3-8.7 gVS/L.d), total solids (65-70%) and total kjeldahl nitrogen (TKN) (23.3- 32.8 g/L) concentrations. It was noted that acclimation of the liquid inoculum to a high concentration of TKN (6.9 g/L) facilitated CM digestion, thereby reducing the start-up phase. The maximum cumulative biogas production rate and specific methane yield were found to be 20 L/d and 0.80±0.12 LCH4g/VSfed, respectively with a methane content over 60% without any signs of inhibition. Operating HSAD at low temperature prevented the accumulation of free-ammonia, which is toxic to methanogens. A techno-economic analysis was also conducted as part of this study to determine the profitability of the system and a 9-year tentative payback period was estimated.

Synergetic effect and mechanism of elementary sulphur, MgSO4 and KH2PO4 progressive reinforcement on pig manure composting nitrogen retention

The potential of sulphur (S), MgSO4 (Mg), and KH2PO4 (P) in nitrogen retention, ammonia emission decrease, and microbial community succession during composting needs to be investigated. To achieve this, different levels of S (0, 0.2, 0.4, 0.6, and 0.8% in dry weight) plus Mg and P (S + Mg + P) were progressively added in 70 days pig manure aerobic composting. The results revealed that the amendment increased salinity and lowered pH and dephytotoxication of the product with the increase of S amount. However, no significant inhibition effects were observed on the evolution of the thermophilic phase and product maturity. In addition, the amendment significantly reduced the total NH3 and N2O emissions by 29.66%–58.81% and 20.6%–56.7%, increased NH4+ level by 17.22%–73.21% in thermophilic phase and NO3− content by 26.17%–57.48% in a mature phase, and elevated the total Kjeldahl nitrogen content by 34.28%–46.6% during the composting. In addition, compared to the control, the supplement markedly encouraged the formation of guanite in the compost product. The S addition stimulated the growth of Anseongella, Actinomadura, Chelativorans, Castellaniella, Luteimonas, and Steroidobacter microbial communities which functioned well in the degradation of nitrogen-containing compounds and organic matter. Evidence from Redundancy Analysis, Firmicutes, Myxococcus, Chloroflexi, Gemmatimonadota, and Deinococcota showed positive correlations with pH. These results imply that adding S–Mg–P amendment encourages the population and activity of specific functional microorganisms, and facilitated the ammonia emission reduction by lowering pH and thus reserved nitrogen through the formation of guanite during composting. The investigation of bacterial community abundance and environmental variables at the phylum and genus levels over time revealed that adding of 0.6% S in conjunction with P and Mg minerals was suitable for nitrogen loss mitigation in composting. The findings suggest using S + Mg + P supplement to conserve nitrogen in pig dung aerobic composting.

Response characteristics of denitrifying bacteria and denitrifying functional genes to woody peat during pig manure composting

This study aimed to explore the impacts of adding different proportions of woody peat (WP) (0%(CK), 5%(T1), and 15%(T2)) on denitrification during composting. The results demonstrated that compared with CK, T1 and T2 increased the total Kjeldahl nitrogen content (8% and 14%, respectively) and reduced the nitrate nitrogen (7% and 23%) content after composting. After composting, the abundances of nirK and nirS decreased by 4–9% and 33–35% under T1 and T2, respectively. Adding 15% WP reduced the abundances of key denitrifying bacteria such as Pseudomonas, Pusillimonas, Achromobacter, and Rhizobiales by 5–90%. The main factors that affected denitrification genes were the carbon content, nitrogen form (nitrite nitrogen and ammonium nitrogen), and denitrifying bacteria community. In summary, adding 15% WP has the best ability to reduce nitrogen loss by decreasing the abundances of denitrifying bacteria and denitrifying functional genes, thereby improving the agricultural value of composting products.

Utilizing In Situ Ultraviolet-Visual Spectroscopy to Measure Nutrients and Sediment Concentrations in Stormwater Runoff

The capacity to collect meaningful data to estimate stormwater runoff water quality and subsequent system removal performance is key to selecting the appropriate solutions to protect water resources. Historically, grab sampling and automated composite sampling approaches have been used with training and comprehensive quality assurance protocols to produce defensible data. Innovative approaches use real-time ultraviolet-visual spectrometry (UV-Vis) can provide a powerful tool for understanding pollutant loading regionally. This study found that real-time UV-Vis sensing is a potential new tool for understanding stormwater effluent pollutant dynamics. Researchers compared data from real-time sensing using UV-Vis spectrometers to develop calibration curves for predicting pollutant concentrations in stormwater flows. Results from paired laboratory data and raw spectral data established calibrations for the stormwater runoff composition and support further investigations of the use of this technology to predict in situ concentrations of total Kjeldahl nitrogen (TKN), dissolved organic carbon (DOC), total phosphorus (TP), total suspended solids (TSS), total nitrogen (TN), and nitrate as nitrogen (NO3−N) resulted in robust models with R2 values in the range 0.99–0.93. Using partial least squares regression (PLSR) methods, the study demonstrated a strong correlation between concentrations generated by the raw absorbance data across the full available spectrum (220 to 730 nm). These results indicate the potential for developing specific stormwater calibration curves for pollutants of interest representative of stormwater runoff. Collectively, these results indicate that real-time UV-Vis spectrometers can redefine stormwater control monitoring by potentially delivering more accurate, more repeatable laboratory quality data instantaneously, with greater efficiency.

Investigating water quality sensitivity to climate variability and its influencing factors in four Lake Erie watersheds

Climate change alters weather patterns and hydrological cycle, thus potentially aggravating water quality impairment. However, the direct relationships between climate variability and water quality are complicated by a multitude of hydrological and biochemical mechanisms dominate the process. Thus, little is known regarding how water quality responds to climate variability in the context of changing meteorological conditions and human activities. Here, a longitudinal study was conducted using trend, correlation, and redundancy analyses to explore stream water quality sensitivity to temperature, precipitation, streamflow, and how the sensitivity was affected by watershed climate, land cover percentage, landscape configuration, fertilizer application, and tillage types. Specifically, daily pollutant concentration data of suspended solid (SS), total phosphorus (TP), soluble reactive phosphorus (SRP), total Kjeldahl nitrogen (TKN), nitrate and nitrite (NOx), and chloride (Cl) were used as water quality indicators in four Lake Erie watersheds from 1985 to 2017, during which the average temperature has increased 0.5 °C and the total precipitation has increased 9%. Results show that precipitation and flow were positively associated with SRP, NOx, TKN, TP, and SS, except for SRP and NOx in the urban basin. The rising temperatures led to increasing concentrations of SS, TKN, and TP in the urban basin. SRP and NOx sensitivity to precipitation was higher in the years with more precipitation and higher precipitation seasonality, and the basins with more spatially aggregated cropland. No-tillage and reduced tillage management could decrease both precipitation and temperature sensitivity for most pollutants. As one of the first studies leveraging multiple watershed environmental variables with long-term historical climate and water quality data, this study can assist target land use planning and management policy to mitigate future climate change effects on surface water quality.

Water chemistry and periphyton biomass in the Rideau River: Have conditions changed after 24 years?

Over the past three decades, the Rideau River (Ontario, Canada) watershed has experienced a land-use change from rural and agricultural land towards urban land, and the introduction and expansion of invasive species. This study examined spatial and temporal patterns of periphyton biomass (chlorophyll-a and ash-free dry mass) collected from riffle zones in 1995 and 2019 along a 66-km stretch of the Rideau River. This study also examined long-term changes in water nutrient and chloride concentrations collected through the Provincial Water Quality Monitoring Network between 2000 and 2018. Declines in total nitrogen between 2000 and 2018 occurred in areas that have not experienced urbanization since the 2000s. In contrast, declines in total phosphorus and increases in chloride between 2000 and 2018 occurred at midstream and downstream sites that have undergone urbanization during the same time period. Conductivity also showed an increase with distance downstream similarly in both 1995 and 2019. Average total phosphorus and total Kjeldahl nitrogen concentrations were lower in 2019 compared to 1995 but did not increase with distance downstream as seen in many river systems, including the Rideau River, in earlier years. Periphyton biomass did not change along the length of the river between 1995 and 2019, despite the declines in nutrient concentrations. These findings highlight the persistence of riverine periphyton in a multi-use watershed experiencing ongoing anthropogenic changes.

Enhancement of Lettuce Growth by PAW Spray Gliding Arc Plasma Generator

The effect of non-thermal air plasma on green oak lettuce farming has been proposed. A gliding arc plasma generator (GAPG) was designed for plasma-activated water (PAW) spray generation. A PAW spray was generated at 8, 10, and 12 kV by a custom-made ac high voltage power supply. Four hydroponic green oak lettuce trays were treated by PAW spray at different conditions for 10 min, three times a day for nine days. The experimental results showed that all the plasma-treated green oak lettuce sprouts had a greater growth rate than the control group. The best condition was found in the PAW spray generated at 8 kV source voltage, which led to the longest average height and width of sprouts of 10.88 ± 0.33 cm and 10.09 ± 0.08 cm, respectively. Moreover, its average dried weight was also significantly greater than that of the control group by 1.69 times. It was found that the concentration of total Kjeldahl nitrogen (TKN), mainly ammonium, was enhanced in every PAW spray condition. However, the highest TKN concentration was found in the 8 kV PAW spray, which was 3.67 times higher than that of the control group. The amount of nitrite (NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−</sup> ) and nitrate (NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−</sup> ) in PAW spray was also enhanced but in the opposite trend to TKN concentration. Moreover, the electrical conductivity (EC) and pH levels could be improved by air plasma. It could be confirmed that the plasma treatment could be effectively applied to green oak lettuce farming, and the PAW spray generated by the GAPG could enhance the amount of nitrogenous fertilizer in treated water, which is essential for plant growth stimulation.

Multi-Scale Analysis of the Dependence of Water Quality on Land Use Using Linear and Mixed Models

Land use influences water quality in streams at different spatial scales and varies in time and space. Water quality has long been associated with agricultural and urban land uses in catchments. The effects of developed, forest, pasture, and agricultural land use on nitrogen, nitrate, and nitrite (NNN); total phosphorus (TP); total suspended solids (TSS); chemical oxygen demand (COD); dissolved oxygen (DO) and total Kjeldahl nitrogen (TKN) concentrations and their sensitivity were quantified to spatial pattern differences. The linear mixed modeling framework was used to examine the importance of spatial extent on models with water quality parameters as the response variable and land use types as the predictor variable. The results indicated that land use categories on different water quality parameters were significant and dependent on the selected spatial scales. Land use exhibited a strong association with total phosphorus and total suspended solids for close reach distances. Phosphorus is not highly soluble, and it binds strongly to fine soil particles, which are transported by water via runoff. Nitrogen, nitrate, and nitrite, dissolved oxygen, chemical oxygen demand, and total Kjeldahl nitrogen concentrations were better predicted for further reach distances, such as 45 or 50 km, where the best model of nitrogen, nitrate, and nitrite is consistent with the high mobility of NO3−.

Viable Putative Vibrio vulnificus and parahaemolyticus in the Pensacola and Perdido Bays: Water Column, Sediments, and Invertebrate Biofilms

Vibriosis is the general term for human illnesses caused by infection of pathogenicVibriospecies.Vibrio vulnificus(Vv) andparahaemolyticus(Vp) are two problematic waterborne pathogens that have yet to be enumerated in northwest Florida coastal Gulf of Mexico estuaries. In this regionally novel study, we surveyed 43 locations in two subtropical estuarine systems, Perdido Bay and Pensacola Bay, over seven dates in winter 2020. Sampling included three substrate types: surface waters, sediments, and invertebrate biofilms. We determined baseline abundances of presumptive viableVvandVpappearing as colonies on CHROMagar (Vv, blue;Vp, purple).Vvwas detected in 37 out of 43 water samples, with maximum levels of 3,556 CFU/mL.Vpwas only detected in 15 water samples, with a maximum concentration of 8,919 CFU/mL. Sediments containedVvin all but one sample, with concentrations ranging from 121 to 607,222 CFU/mL. In contrast,Vpwere only detected in 33 sediment samples, where concentrations ranged from 28 to 77,333 CFU/mL. Opportunistically-sampled surface swabs (biofilms), collected from shells (either oyster or barnacle) and polychaete worms found in sediment samples, contained on average 7,735 and 1,490 CFU/mL ofVvandVp, respectively. Surface waterVvabundances covaried with bottom water pH, maximum prior cumulative wind speeds, and tidal coefficient on the day of sampling.Vpsurface water abundances negatively correlated with surface water salinity, surface water pH, and bottom water pH and positively correlated with total surface dissolved inorganic and total Kjeldahl nitrogen concentrations, and wind. Spatially, there was large variation inVibriodensities in surface waters; abundances of both species were strongly correlated with wind, suggesting resuspension was important. Sedimentary abundances of both putativeVvandVpshared a correlation with one parameter: salinity stratification. Due to the length of this study, temperature was not considered a major factor. This short-term (1 month) study was designed not to enumerate pathogenicVvorVp, but rather to establish the first winter baseline ofVibrioabundances for this region. Determination of these baseline winter cultivable putativeVibrioabundances will be valuable in predicting relative risk factors in each waterbody of interest.

Nutrient Concentrations in Macrophytes from Lotic and Lentic Environments of the Middle Parana River, Argentina

Objectives: The purpose of this work was to compare nutrient concentrations in water, sediment, and in plant tissues of Eichhornia crassipes and Panicum elephantipes from lotic and lentic environments of the Middle Parana River floodplain (Argentina). Materials and Methods: The study was carried out over an 18-month period. Plants, water, and sediment were collected in a lake (lentic environment) and in a river (lotic environment) from the Middle Parana River floodplain. Water and sediment were sampled in sites where P. elephantipes or E. crassipes were predominant and in sites without vegetation. Results and Discussion: The lentic and lotic environments dominated by E. crassipes showed the highest ammonium concentrations. The sediment from the lotic environment showed total phosphorus (TP) and total Kjeldahl nitrogen (TKN) concentrations significantly lower than those found in the sediment from the lentic environment. In the lentic environment, the sediment from the lake with the dominance of E. crassipes showed the highest TKN concentration, while the sediment from the lake dominated by P. elephantipes showed the highest TP concentration. For both plant species and for both environments, TKN and TP tissue concentrations were significantly higher in leaves in comparison with roots. Conclusions: Our results could be used to optimize the efficiency of treatment wetlands. Additionally, the use of locally available macrophytes as contaminant bioaccumulators in the Middle Parana River floodplain is completely feasible.

Long-term performance of three mesophilic anaerobic digesters to convert animal and agro-industrial wastes into organic fertilizer

Few studies have investigated the performance of anaerobic digestion (AD) to convert animal and agro-industrial wastes to organic fertilizers over a long-term field conditions. This paper studied three large-scale mesophilic digesters (D1–D3) over two years for their effects on feedstocks, which were dairy manure for D1 and D2 and co-digestion mixed manure and agro-industrial wastes for D3. Hydraulic retention times (HRT) were 9 d for D1, 12 d for D2, and 34 d for D3. Digester influent and effluent samples were taken every two months from the digesters and analyzed for pH, and concentrations of total solids (TS), ammonium nitrogen (NH4-N), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and eight metals. The study revealed high variability in converting feedstock in the three digesters. Compared with their respective influent, the mean digester effluent pH decreased from 7.9 by 0.6 in D1 (p < 0.01) and by 0.3 in D2 (p < 0.01), but it increased from 6.1 by 1.8 in D3 (p < 0.01). The mean digester effluent TS increased from 3.4% by 0.1% (p > 0.05) in D1, but it decreased from 4.9% by 1.3% in D2 (p < 0.05) and from 12.3% by 4.8% in D3 (p < 0.01). All three digesters significantly increased NH4-N concentrations by 21.4–81.8% (p < 0.05), but insignificantly changed TKN and TP concentrations (p > 0.05). Effects of AD on all metal concentrations were mixed and were insignificant (p > 0.05) because of large concentration variations. However, study of a ratio quotient (qMg) using magnesium (Mg) as the reference discovered accumulation of NH4-N, copper, potassium, and sodium, but loss of TKN, TP, iron, manganese, zinc, and calcium during AD for D2 and D3. The impact of AD conversion was closely related with types of feedstock (on pH) and HRT (on TS and NH4-N). The results of this study can assist in developing strategies for cleaner production using AD in an environmentally sustainable manner.

Increasingly severe cyanobacterial blooms and deep water hypoxia coincide with warming water temperatures in reservoirs.

Cyanobacterial blooms are expected to intensify and become more widespread with climate change and sustained nutrient pollution, subsequently increasing threats to lentic ecosystems, water quality, and human health. However, little is known about their rates of change because long-term monitoring data are rare, except for some well-studied individual lakes, which typically are large and broadly dispersed geographically. Using monitoring data spanning 1987-2018 for 20 temperate reservoirs located in the USA, we found that cyanobacteria cell densities mostly posed low-to-moderate human health risks until 2003-2005, after which cell densities rapidly increased. Increases were greatest in reservoirs with extensive agriculture in their watersheds, but even those with mostly forested watersheds experienced increases. Since 2009, cell densities posing high human health risks have become frequent with 75% of yearly observations exceeding 100,000cellsml-1 , including 53% of observations from reservoirs with mostly forested watersheds. These increases coincided with progressively earlier and longer summer warming of surface waters, evidence of earlier onset of stratification, lengthening durations of deep-water hypoxia, and warming deep waters in non-stratifying reservoirs. Among years, higher cell densities in stratifying reservoirs were associated with greater summer precipitation, warmer June surface water temperatures, and higher total Kjeldahl nitrogen concentrations. These trends are evidence that expected increases in cyanobacterial blooms already are occurring as changing climate conditions in some regions increasingly favor their proliferation. Consequently, their negative effects on ecosystems, human health, and socioeconomic wellbeing could increase and expand if warming trends and nutrient pollution continue.

Potential Viable Products Identified from Characterisation of Agricultural Slaughterhouse Rendering Wastewater

The composition of challenging matrices must be fully understood in order to determine the impact of the matrix and to establish suitable treatment methods. Rendering condensate wastewater is a complex matrix which is understudied. It is produced when the vapour from rendering facilities (heat processing of slaughterhouse waste material) is cooled as a liquid for discharge. This study offers a full physicochemical characterisation of rendering condensate wastewater and its potential for valorisation via production of viable by-products. A study of seasonal variation of levels of dissolved oxygen, chemical oxygen demand, total nitrogen and ammonia was carried out on the wastewater. The results show that the wastewater was high strength all year-round, with a chemical oxygen demand of 10,813 ± 427 mg/L and high concentrations of total Kjeldahl nitrogen (1745 ± 90 mg/L), ammonia (887 ± 21 mg/L), crude protein (10,911 ± 563 mg/L), total phosphorous (51 ± 1 mg/L), fat and oil (11,363 ± 934 mg/L), total suspended solids (336 ± 73 mg/L) and total dissolved solids (4397 ± 405 mg/L). This characterisation demonstrates the requirement for adequate treatment of the condensate before releasing it to the environment. While there is a reasonably constant flow rate and dissolved oxygen level throughout the year, higher chemical oxygen demand, total nitrogen and ammonia levels were found in the warmer summer months. From this study, rendering condensate slaughterhouse wastewater is shown to have potential for production of marketable goods. These products may include ammonium sulphate fertilizer, protein supplements for animal feeds and recovery of acetic acid calcium hydroxyapatite, thus enhancing both the financial and environmental sustainability of slaughterhouse operations. This work demonstrates a valuable assessment of a complex wastewater, while taking advantage of on-site access to samples and process data to inform the potential for wastewater reuse.

Differences in the Composition of Leachate from Active and Non-Operational Municipal Waste Landfills in Poland

Leachate formation is one of the many environmental hazards associated with landfilling. The leachate may migrate from the landfill to surface water and groundwater, posing a potential threat to aquatic ecosystems. Moreover, its harmful effect on human health and life has been proven. Due to the risks that landfill leachates may pose, it is necessary to control the state of the environment in their surroundings. The paper presents an example of the application of selected statistical methods (basic statistics, statistical tests, principal component analysis) to assess the impact of individual pollution indicators on the quality of landfill leachates. The conducted analysis showed the existence of significant differences between the surveyed active (Legnica, Jawor) and non-operational (Wrocław, Bielawa) landfills in Poland. These differences were especially visible in the cases of the following: electric conductivity (EC) (non-operational landfills 1915–5075 μS/cm, active 5093–11,370 μS/cm), concentrations of total Kjeldahl nitrogen (TKN) (non-operational landfills 0.18–294.5 mg N/dm3, active 167.56–907.4 mg N/dm3), chemical oxygen demand (COD), organic nitrogen (ON), ammonium nitrogen (AN), total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), sulfates, chlorides, sodium, potassium, calcium, magnesium and nickel. Selected indicators should help to determine the progress of decomposition processes inside the landfill and the potential impact of leachate on the environment, and should be used in the mandatory monitoring of landfills.

Phytoremediation potential of Echinochloa crus galli and Hibiscus cannabinus in the stabilization of municipal wastewater sludge

In this study, the phytoremediation potential of municipal sewage sludge was studied by Echinochloa crus galli and Hibiscus cannabinus plants with special reference to total organic carbon, total Kjeldahl nitrogen, total phosphorus, sodium uptake ratio, pH, electrical conductivity and lead and cadmium heavy metals. Design and construction of E. crus galli beds in Kermanshah and E. crus galli and H. cannabinus in Sarpol Zahab wastewater treatment plant was carried out at the outdoor. In Kermanshah wastewater treatment plant, the removal efficiency of total organic carbon in phytoremediation by E. crus galli increased with maturity and reached 62 ± 1.3% (P < 0.05). At the end of 75 days, total phosphorus and total Kjeldahl nitrogen concentrations were 1.8 ± 0.24 and 1.49 ± 0.18%, respectively. Lead removal efficiency was significantly high, and cadmium concentration which in crude sludge was 0.08 mg/kg decreased to zero (P < 0.05). In Sarpol Zahab wastewater treatment plant, the efficiency of total organic carbon, lead and cadmium phytoremediation by E. crus galli was high. The removal efficiency of total organic carbon in H. cannabinus treatment increased with time (P < 0.05). Though, the nutrient removal efficiency was moderate. The removal efficiency of lead and cadmium significantly increased during the experiments. It can be concluded that the studied plants can be used to remove heavy metals such as lead and cadmium and total organic carbon and to some extent nutritious from municipal sewage sludge. However, the yield of plants varied according to the culture medium. It also increased with increasing ripening time and electrical conductivity and decreasing pH.

Evaluating the effect of seasonal temperature changes on the efficiency of a rhizofiltration system in nitrogen removal from urban runoff

The study presents an evaluation of nitrogen removal efficiency of a pilot-scale rhizofiltration system in Pretoria, South Africa. The rhizofiltration system was divided into two sections, one side planted with common reeds (Phragmites australis) and the other side was without plants kept as a control. The objective of the study was to evaluate the influence of seasonal temperature on the removal of nitrogen species from the simulated urban runoff using the rhizofiltration system. The final effluent from the filter was collected bimonthly at different sampling points for 10 months after an application time of 5 min and 25 min. Duplicate samples were taken to determine the concentrations of TKN (Total Kjeldahl nitrogen), ammonium, nitrate and chemical oxygen demand (COD) for the raw influent and final effluent from the rhizofiltration system. Temperature and pH were determined on-site.During the monitoring period, there was no significant difference in the inflow concentration of ammonium in colder and warmer months for both planted and control sides. Furthermore, the composition of the feed medium to the rhizofilter was kept the same in both cold and warm season and for both planted and control sides. The removal of ammonium in colder and warmer months was not significant in both systems. At an average temperature increase of 5.2 °C in the warmer months, the ammonium removal efficiency in the planted side increased by 7.5%, while for the control side the removal efficiency increased by 2.4%. The difference in removal was not significant between the averages of effluent ammonium after an application time of 25 min in colder versus warmer months for the planted and control sides of the system. Furthermore, an increased nitrification rate was more evident in the planted than in the control side, which was subsequently denitrified. It was observed that 60.4% of nitrate concentration was potentially removed in the planted side whereas 45.4% was potentially denitrified in the control side. These results suggest positive correlation between nitrate concentration and the potential for denitrification. The nitrate removal efficiency dropped to 32.2% for the planted site and to 26.1% for the control system in colder months. Temperature had an effect on nitrogen removal, since nitrogen removal efficiency decreased in colder months. Complete nitrogen removal could not be achieved under the operating conditions.

Nouveau design solar septic tank: Reinvented toilet technology for sanitation 4.0.

The up-flow solar septic tank (UTST) and multi-soil layering (MSL) system has been developed and proposed as “Nouveau Design Solar Septic Tank”. The objective of this study was to verify functionality of the integrated UTST and MSL system for treatment of toilet wastewater (or black water) under actual conditions over a year at the Asian Institute of Technology campus, Pathumthani province, central Thailand. During the operation period which involved fluctuating flow rates, ambient temperatures and black water characteristics, the UTST unit yielded satisfactory performance with the average treatment efficiencies of 9210% for total chemical oxygen demand (TCOD), 7910% for soluble chemical oxygen demand (SCOD), 939% for total 5-days biochemical oxygen demand (TBOD) and 9012% for soluble 5-days biochemical oxygen demand (SBOD), respectively, while the MSL unit could remove 95 3%, and 88 15% of total kjeldahl nitrogen (TKN) and total phosphorus (TP), respectively. The effluent TCOD, TBOD, TKN, nitrite (NO2-N), nitrate (NO3-N), ammonia (NH3) and TP concentrations of the integrated UTST and MSL system were 3927,827,55 mg/L, 22,3924,89,25 and 11 mg/L, respectively, meeting the ISO requirements. The removal efficiencies of TCOD, SCOD, TBOD and SBOD exhibited positive correlation with the ratios of TBOD/TKN, TBOD/SBOD and TBOD/TP. With high treatment efficiencies and effluent quality meeting the ISO requirements, the nouveau design solar septic tank has been demonstrated as an innovative technology toward the sanitation 4.0 concept and the Sustainable Development Goal no. 6 (SDG6).

Modified electrochemical processes for industrial-scale treatment of wastewater having high TKN content

Electrochemical phenomena were implemented to treatment of industrial wastewater containing high nitrogen concentrations. Organic nitrogen and ammonia, measured by Total Kjeldahl Nitrogen (TKN), raise concerns for most conventional wastewater treatment plants having limited capability of their removal. To avoid contamination of ecosystems with an excessive nitrogen discharge, environmental regulations do not permit for dilution of effluent containing nitrogenous compounds but rather require their adequate removal. This is a challenge for many industrial facilities producing wastewater containing TKN at the level of thousands milligrams per liter. The studied wastewater comprised such TKN along with a significant concentration of ferrous ions in a dissolved form. It was found that ferrous ions in so high concentrations could be advantageous as they provide a platform for designing a sustainable process. In this study, combined electrochemical advanced oxidation and modified electro-Fenton like process was designed and validated at three distinct scales with the goal of finding a scalable solution for TKN removal. An Electro-Fenton Sequential Batch Reactor (EF-SBR) was developed to facilitate the removal efficiency of ammonia and TKN, by more than 99% and 98%, respectively. The reproducibility of the process was validated through several SBR cycles. Moreover, the implementation of EF-SBR permitted to optimize the specific energy consumption and resulted in a pronounced decrease in sludge production.