Nutrient Removal Research Articles

Effect of Harvest Management on Biomass Yield, Forage Quality, and Nutrient Removal by Bioenergy Grasses in Mid-Central Virginia

The increasing cost of fossil-based energy sources has driven research in bio-based alternatives, such as perennial grasses for feedstock. The mid-Atlantic receives appreciable summer rainfall that may support a two-cut-per-year−1 harvest. At Virginia State University, a study on annual forage sorghum and two one-year stand perennials, miscanthus, and selected switchgrass ecotypes was carried out. The experimental design was a split-plot with harvest systems and feedstock grass species randomly assigned to the main and sub-plots, respectively. Only perennial grasses were assigned to the two-cut-per-year−1 system. The first cut occurred in early summer, and the second and single cut occurred after the frost-kill. Under the two-cut system, in 2022, the first-cut dry matter (DM) yield ranged from 8.9 Mg ha−1 in Blackwell to 14.7 Mg ha−1 in BoMaster. Additionally, except for BoMaster, the regrowth DM yields were within 10% of the first-cut DM yield. Under the one-cut system, the yield ranged from 10.8 Mg ha−1 in Blackwell to 23.2 Mg ha−1 in sorghum. Under the two-cut system, in 2023, miscanthus produced the greatest first-cut DM yield of 18.4 Mg ha−1, while other perennials averaged 10.1 Mg ha−1. Compared to the first cut, the hot and dry summer significantly reduced regrowth for all feedstock species, with the miscanthus DM yield dropping by 64%. While forage attributes differ among feedstock species, in general, both the first cut and regrowth showed greater crude protein and mineral elements, as well as lower ADF contents compared to a single cut following a killing freeze. Sorghum had better forage quality for the one-cut-per-year−1 feedstock material, and, along with the first cut and regrowth, it may have the potential for use as forage for maintenance energy in animal systems. For perennials, the two-cut-per-year−1 system removed the greatest quantities of nutrients during both years, with the first-cut harvest contributing about 65% of all removed N and K. Sorghum removed the greatest quantities of nutrients compared to the perennial under a one-cut-per-year−1 system. Therefore, while a two-cut-per-year−1 system can result in the greatest DM yields for dual-purpose use, its adoption calls for a critical analysis of economic benefits that considers feedstock bioenergy processing approaches, stand persistence, and fertilizer management strategies to address potential soil fertility depletion due to mineral element mining.

Dynamics of nutrient removal and N2O emissions in an ecological ditch with different plant combinations

Dynamics of nutrient removal and N2O emissions in an ecological ditch with different plant combinations

Nutrient removal and biomass production of marine microalgae cultured in recirculating aquaculture systems (RAS) water with low phosphate concentration

This study was conducted to investigate the feasibility of microalgal biomass production and nutrient removal from recirculating aquaculture systems (RAS) water (RASW) with low phosphate concentration. For this purpose, Nannochloropsis oculata, Pavlova gyrans, Tetraselmis suecica, Phaeodactylum tricornutum, and their consortium were cultivated in RASW and RASW supplemented with vitamins (+V). Among them, N. oculata showed the maximum biomass production of 0.4 g/L in RASW. Vitamins supplementation significantly increased the growth of T. suecica from 0.16 g/L in RASW to 0.33 g/L in RASW + V. Additionally, T. suecica showed the highest nitrate (NO3–N) removal efficiency of 80.88 ± 2.08 % in RASW and 83.82 ± 2.08 % in RASW + V. Accordingly, T. suecica was selected for scaling up study of microalgal cultivation in RASW and RASW supplemented with nitrate (RASW + N) in 4-L airlift photobioreactors. Nitrate supplementation enhanced the growth of T. suecica up to 2.2-fold (day 15). The fatty acid nutritional indices in T. suecica cultivated in RASW and RASW + N showed optimal polyunsaturated fatty acids (PUFAs)/saturated fatty acid (SFAs), omega-6 fatty acid (n-6)/omega-3 fatty acid (n-3), indices of atherogenicity (IA), and thrombogenicity (IT)). Overall, the findings of this study revealed that despite low phosphate concentration, marine microalgae can grow in RASW and relatively reduce the concentration of nitrate. Furthermore, the microalgal biomass cultivated in RASW consisting of pigments and optimal fatty acid nutritional profile can be used as fish feed, thus contributing to a circular bioeconomy.

Growth, nutrient removal, and lipid productivity promotion of Chlorella sorokiniana by phosphate solubilizing bacteria Bacillus megatherium in swine wastewater: Performances and mechanisms

Effects of a phosphorus-solubilizing bacteria (PSB) Bacillus megatherium on growth and lipid production of Chlorella sorokiniana were investigated in synthesized swine wastewater with dissolved inorganic phosphorus (DIP), insoluble inorganic phosphorus (IIP), and organic phosphorus (OP). The results showed that the PSB significantly promoted the algal growth in OP and IIP, by 1.10 and 1.78-fold, respectively. The algal lipid accumulation was also greatly triggered, respectively by 4.39, 1.68, and 1.38-fold in DIP, IIP, and OP. Moreover, compared with DIP, OP improved the oxidation stability of algal lipid by increasing the proportion of saturated fatty acids (43.8 % vs 27.9 %), while the PSB tended to adjust it to moderate ranges (30.2–41.6 %). Further, the transcriptome analysis verified the OP and/or PSB-induced up-regulated genes involving photosynthesis, lipid metabolism, signal transduction, etc. This study provided novel insights to enhance microalgae-based nutrient removal combined with biofuel production in practical wastewater, especially with complex forms of phosphorus.

Nutrient removal and emission of nitrous oxide and methane by a sequencing batch reactor treating wastewater with and without landfill leachate

Wastewater and landfill leachate treatment processes have the potential to generate nitrous oxide (N2O) and methane (CH4), both significant greenhouse gases (GHG). However, little is known about these emissions when a combined treatment approach (wastewater with leachate) is utilized. This study aimed to assess the emissions of these gases and nutrient removal in an anaerobic/aerobic/anoxic sequencing batch reactor (SBR) employed for treating wastewater with landfill leachate (1% v/v). Leachate contributes significantly to the removal of organic matter and nutrients, primarily phosphorus. The production and emission of N2O occurred during the aerobic phase, whereas CH4 was produced in the anaerobic and anoxic phases. This gas was emitted at the beginning of the aerobic phase and in the end of anoxic phase. The emission factors obtained in this work were 0.0108 and 0.0119 kg N2O-N per kg TNinfluent and 0.000225 and 0.000253 kg CH4-C per kg CODinfluent with and without landfill leachate, respectively. Regarding CO2-equivalent, the N2O was the major contributor, accounting for 99% of the emitted GHG by the process. Further studies are required; however, the main findings of this study suggest that this system may be appropriate when lower GHG emissions are required.

New insights into substrates shaped nutrients removal, species interactions and community assembly mechanisms in tidal flow constructed wetlands treating low carbon-to-nitrogen rural wastewater

A limited understanding of microbial interactions and community assembly mechanisms in constructed wetlands (CWs), particularly with different substrates, has hampered the establishment of ecological connections between micro-level interactions and macro-level wetland performance. In this study, CWs with distinct substrates (zeolite, CW_A; manganese ore, CW_B) were constructed to investigate the nutrient removal efficiency, microbial interactions, metabolic mechanisms, and ecological assembly for treating rural sewage with a low carbon-to-nitrogen ratio. CW_B showed higher removal of ammonia nitrogen and total nitrogen by about 1.75–6.75 % and 3.42–5.18 %, respectively, compared to CW_A. Candidatus_Competibacter (denitrifying glycogen-accumulating bacteria) was the dominant microbial genus in CW_A, whereas unclassified_f_Blastocatellaceae (involved in carbon and nitrogen transformation) dominated in CW_B. The null model revealed that stochastic processes (drift) dominated community assembly in both CWs; however, deterministic selection accounted for a higher proportion in CW_B. Compared to those in CW_A, the interactions between microbes in CW_B were more complex, with more key microbes involved in carbon, nitrogen, and phosphorus conversion; the synergistic cooperation of functional bacteria facilitated simultaneous nitrification-denitrification. Manganese ores favour biofilm formation, increase the activity of the electron transport system, and enhance ammonia oxidation and nitrate reduction. These results elucidated the ecological patterns exhibited by microbes under different substrate conditions thereby contributing to our understanding of how substrates shape distinct microcosms in CW systems. This study provides valuable insights for guiding the future construction and management of CWs.

A cloud-based infrastructure to deploy supervisory forecast models for predictive coagulant dosing control

Abstract Advanced optimal dosing control based on multiple online sensor data is operational in several treatment facilities in Norway. The benefits of the dosing control system in maintaining stable phosphate/solids removal and saving coagulant usage are documented in the literature. The dosing algorithm is currently implemented in a programmable logic controller (PLC) connected to the treatment plant's Supervisory Control and Data Acquisition System (SCADA) system. The PLC receives online sensor data from the plant's SCADA, calculates the optimal dosing values, and transmits optimal dosage values back to the SCADA system. The dosing algorithm is frequently updated to keep in sync with the process and equipment upgrades of the treatment plant and advances in control algorithm schemes. The upgrades include new regulatory feedback loops structural changes to the dose equation, and the addition of conditional setpoints. Each maintenance and upgrade routine entails operational downtime where the dosing algorithm is set to a sub-optimal flow-proportional dose. This paper presents a non-intrusive Internet of Things (IoT) infrastructure to implement a predictive/forecast component to an existing dosing control algorithm. The benefits of the new cloud-based system in improving nutrient removal, increasing operational flexibility, and reducing maintenance downtime are presented in this work.

Nitrogen and phosphorus removal from synthetic aquaculture water through electrocoagulation

In this research, we utilized multivariate analysis to evaluate the efficient removal of nitrogen and phosphorus from synthetic aquaculture water using the electrocoagulation process. The elimination of nitrogen and phosphorus is a critical issue in various wastewater treatment plants and aquaculture systems, especially in instances of intensive or super-intensive cultivation. To avert the buildup of pollutants in the water, be it within internal recirculation systems or bodies of water receiving effluents from rearing tanks, it is imperative to employ treatment methodologies designed to effectively eliminate nitrogen and phosphorus nutrients. These nutrients have the potential to induce eutrophication in aquatic ecosystems. However, conventional biological treatment technologies can be ineffective, as they often only remove one pollutant or the other. Furthermore, the individual operations for these systems are complex and require substantial space. Electrocoagulation is a compact and promising technology for treating aquaculture water and effluents for raw nutrient removal. In this context, our findings showcase the simultaneous removal of both nitrogen and phosphorus through the electrocoagulation method. The best treatment was verified for the highest electrical current density (74 A. m-2), the shortest distance between electrodes (4 cm), and the lowest electrolysis time (50 min). In these conditions, the efficiency removal in ammonia nitrogen and total phosphorus were 30.5% and 100% respectively. Keywords: electrochemical treatment, eutrophication, water pollution control.

Potential of hospital wastewater treatment using locally isolated Chlorella sp. LH2 from cocoon wastewater

Chlorella sp. is able to grow and transform inorganic and organic contaminants in wastewater to create biomass. In the present study, Chlorella sp. LH2 isolated from cocoon wastewater was able to thrive in hospital wastewater, then remove nutrients and eliminate E. coli ATCC 8739. The results indicated that optimal cultivation conditions of Chlorella sp. LH2 in hospital wastewater were pH of 8, light:dark cycle of 16:8 at 30oC. The inhibitory effect of chlorination on algae growth was accompanied with the chlorine concentration. BOD5:COD ratio of 0.77 indicated biodegradability of hospital wastewater. The untreated and treated wastewatee samples were collected to investigated the nutrient removal efficiency after 10 days. Untreated and treated results were192 ± 8.62 mg/l 23.91 ± 2.19 mg/l for BOD5; 245 ± 9.15 mg/l and 47.31 ± 5.71 mg/l for COD. The treated value met the required standards for hospital wastewater treatment. The removal efficiency total nitrogen and total phosphorus were 68.64% and 64.44% after 10 days, respectively. Elimination of E. coli ATCC 8739 after 7 days by Chlorella sp. LH2 was 88.92%. The results of this study suggest the nutrients and pathogens removal potential of Chlorella sp. LH2 in hospital wastewater for further practical applications.

Selection of microalgae in artificial digestate: Strategies towards an effective phycoremediation

Digestate is a complex by-product of anaerobic digestion and its composition depends on the digestor inputs. It can be exploited as a sustainable source of nutrients for microalgae cultivation but its unbalanced composition and toxic elements make the use challenging. Screening algae in a simplified synthetic digestate which mimics the main nutrient constraints of a real digestate is proposed as a reproducible and effective method to select suitable species for real digestate valorisation and remediation.Growth performance, nutrient removal and biomass composition of eight microalgae exposed to high amounts of NH4+, PO4− and organic-C were assessed. Using a score matrix, A. protothecoides, T. obliquus, C. reinhardtii, and E. gracilis were identified as the most promising species. Thus, three strategies were applied to improve outcomes: i) establishment of an algal consortium to improve biomass production, ii) K+ addition to the medium to promote K+ uptake over NH4+ and to reduce potential NH4+ toxicity, iii) P starvation as pretreatment for enhanced P removal by luxury uptake.The consortium was able to implement a short-term response displaying higher biomass production than single species (3.77 and 1.03–1.89 mg mL−1 respectively) in synthetic digestate while maintaining similar nutrient remediation, furthermore, its growth rate was 1.6 times higher than in the control condition. However, the strategies aiming to reduce NH4+ toxicity and higher P removal were not successful except for single cases. The proposed algal screening and the resulting designed consortium were respectively a reliable method and a powerful tool towards sustainable real digestate remediation.

Evaluating The Potential of Hibiscus Rosa-Sinensis in Floating Wetland for The Remediation of Water Bodies Polluted with Domestic Sewage

The inadequate infrastructure for wastewater treatment in many regions has led to the contamination of surface water bodies and groundwater degradation. To address this issue, floating wetland treatment systems have emerged as a viable alternative for effective wastewater remediation. This study focuses exclusively on utilizing Hibiscus rosa-sinensis, a tropical ornamental plant, within the context of floating wetland treatment techniques for the remediation of domestic wastewater. The primary objective is to assess the nutrient and pollutant removal efficiency of Hibiscus rosa-sinensis in a laboratory-scale floating wetland system. Healthy Hibiscus rosa-sinensis plants were cultivated on identical floating rafts and placed in plastic tanks filled with domestic sewage for experimental investigation. Water quality analyses were conducted regularly, spanning 0, 3, 5, 10, 15, 20, and 25 days HRT. The results of this experimental investigation revealed that Hibiscus rosa-sinensis, when used in floating wetland treatment, exhibited significant removal efficiencies for various parameters, including turbidity, total suspended solids (TSS), total phosphorus (TP), ammonia, and dissolved oxygen (DO).These findings highlight the potential of Hibiscus rosa-sinensis plants as a practical component of floating wetland systems for removing nutrients and pollutants from domestic wastewater. This research underscores the viability of Hibiscus rosa-sinensis as a sustainable and environmentally friendly solution to address water pollution challenges, particularly in the context of floating wetland treatment.

Seasonal Stream Water Chemistry Response To Long-Term Forestry Drainage And Wildfire: A Case Study In A Part Of The Great Vasyugan Mire

Recent research suggests that climate change is contributing to rising solute concentrations in streams. This study focuses on assessing the concentrations of major elements, nutrients, and dissolved organic carbon (DOC), and their release through the bog-river system in the taiga zone of Western Siberia. The research was carried out in the northeastern part of the Great Vasyugan Mire (GVM), the largest mire system that impacts the quality of river water in the Ob River basin. By using PCA and cluster analysis, we examined the long-term dynamics of the chemical composition of headwater streams of the GVM affected by drainage and wildfires. Our data from 2015-2022 revealed that the concentrations of Са2+, Mg2+, K+, Na+, and HCO3- in stream water from the drained area of the GVM were, on average, 1.3 times lower than those at the pristine site. Conversely, the concentrations of NH+4, Fetotal, Cl-, SO42-, NO-3, DOC, and COD were higher, indicating the influence of forestry drainage and the pyrogenic factor. Our findings also demonstrated that the GVM significantly impacts the water chemical composition of small rivers. We observed a close correlation in the concentrations of К+, Na+, Cl-, Fetotal, NH+4, HCO3-, and COD between the GVM and the Gavrilovka River waters. PCA analysis revealed that air temperature influences the concentrations of Са2+, Mg2+, NH4+, NO3-, HCO3-, Fetotal, and DOC in the studied streams, with an inverse correlation with river discharge. The removal of major elements, nutrients, and DOC from the drained area of the GVM was most pronounced in April, being twice as high as in the pristine area. However, the total export from the drainage area of the Gavrilovka in April-September 2022 was 1.3 times lower than in the pristine area, amounting to 8487 kg/km2, with DOC removal at 42%.

Exogenous compound bacteria enhance the nutrient removal efficiency of integrated bioremediation systems: Functional genes and microorganisms play key roles

With the continuous development of intensive mariculture, the application of the integrated bioremediation system of aquaculture wastewater (IBSAW) is increasingly promoted. However, the process and nutrients removal performance of the IBSAW need to be further optimized due to its immature technologies. In this study, exogenous compound bacteria (ECB) were added to IBSAW to investigate its pollutants removal efficiency and the relevant mechanisms. High-throughput sequencing and Geochip gene array were used to analyze the correlation between nutrients and bacteria, and the abundance of N and P cycling genes were quantified. Multivariable statistics, dimensionality reduction analysis, and network analysis were applied to explore the mechanisms of IBSAW operation. The results showed that the nutrients decreased significantly after adding ECB, with the brush treatment group significantly outperforming the ceramsite in removing NO3− and PO43−. Ceramsite has an advantage in removing NO2−-N. The addition of ECB and different substrates significantly affected the composition of bacterial communities. The contents of nosZ and nirKS related to denitrification in the treatment groups were significantly higher than those in the control group, and the contents in the brush treatment group were significantly higher than that of ceramsite. The biomarkers Psychroserpens and Ruegeria on the biofilm of the brush treatment group were positively correlated with nirKS, while Mycobacterium, Erythrobacter and Paracoccus, Pseudohaliea in the ceramsite group were positively correlated with nirS and nirK, respectively. Therefore, it is speculated that the ECB significantly promoted the increase of denitrification bacteria by affecting the composition of bacterial communities, and the ECB combined with functional genera improved the efficiency of nutrients removal in the system. This study provided a reference for understanding the process and mechanism of nutrients removal, optimizing the wastewater purification technology of the IBSAW and improving the performance of the system.

Synergistic interactions of light and dark biofilms in rotating algal biofilm system for enhanced aquaculture wastewater treatment

Aquaculture wastewater management is critical for environmental sustainability. This study investigates the synergistic interactions between light and dark biofilms with a Rotating Algal Biofilm (RAB) system for effective aquaculture wastewater treatment. The RAB system, optimized with a 5-day harvest time and 12-hour hydraulic retention time, demonstrated superior biomass productivity (3.3 g m−2 d−1) and total ammoniacal nitrogen removal (82.3 %). Comparative analysis of light and dark biofilms revealed their complementary roles, with the light side exhibiting higher carbon assimilation and nutrient removal efficiencies, while the dark side contributed significantly to denitrification and phosphorus removal. Microbial community analysis highlighted the dominance of key bacterial genera such as Haliangium, Methyloversatilis and Comamonadaceae, along with the algal genus Chlorella, indicating their crucial roles in nutrient cycling. This study provides insights into the operational dynamics of RAB system for sustainable aquaculture wastewater treatment.

Evaluation of Microalgae Chlorella vulgaris and Tetradesmus bernardii for Cultivation and Nutrient Removal in Palm Oil Mill Effluent

The palm oil industry is one of the key players in contributing to Malaysia’s economy. Palm oil mill effluent (POME), a significant by-product of the oil extraction process, requires mandatory remediation to ensure proper treatment and disposal. Bioremediation using microalgae is a cost-effective and sustainable approach. This study aims to utilise pure and mixed microalgal species, Chlorella vulgaris and Tetradesmus bernardii, in phycoremediation and biomass production in different concentrations of POME (20%, 40%, 60%, and 80%). Cultivation of microalgae was carried out in 200 mL medium with pH 7–7.8, room temperature of 25±1°C for 21 days and continuous light illumination at 2000 lux. The highest biomass productivity was observed in 20% POME for mixed microalgae (mean = 0.1733 mg.mL-1 ± 0.0057), followed by C. vulgaris (0.1633 mg.mL-1 ± 0.0057) and T. bernardii (0.1603 mg.mL-1 ± 0.0020). Similarly, the highest nutrient removal was observed in 20% POME for mixed microalgae (COD:66.9801%, TN:86.9565%, TP:86.9655%), followed by C. vulgaris and T. bernardii. The results showed positive effects on growth, increased biomass production, and nutrient removal, with 20% POME being the optimal concentration for microalgae. Valuable by-products, such as high-quality pigments and biomass, are also generated by applying microalgae for remediation. Mixed microalgae are superior in the remediation of POME compared to single-culture algae. Treating wastewater through microalgal bioremediation is highly efficient in nutrient removal. This research has contributed towards the use of mixed microalgae to achieve effective nutrient removal and biomass for future industrial applications.

Performances of constructed wetland system to treat whey and dairy wastewater during a macrophytes life cycle

Constructed wetlands system (CWs) have been proposed as an economical, efficient and sustainable wastewater treatment technology. The aim of this paper was to provide the first published data on the efficiency of CWs for dairy wastewater treatment in Tunisia. In most CWs, good organic, total suspended solids (TSS) and nutrient removal was measured. In order to evaluate the efficiency of this process, hybrid small-scale wetland system was designed containing three horizontal subsurface flow (HSSF) and one free water surface flow (FWS). A mixture of Reeds (Phragmites australis), Cattails (Typha latifolia), and Papyrus (Cyperus papyrus) was planted. Several water quality parameters in both raw and treated wastewaters were monitored during the macrophytes life cycle. The average influent properties for 20 % of whey are: TSS (3040 mg/L), COD (5060 mg O2/L), BOD5 (3020 mg O2/L), TKN (79 mg N/L) and TP (32,2 mg P/L). Removal efficiencies of 99.6 % for TSS, 80 % for COD, 97 % for BOD5, 90.4 % for TKN and 99.6 % for TP were observed. The results reveal temporal variations in system performance according to macrophyte growth rates. Reeds, Cattails and Papyrus start their life cycle at the beginning of the winter and continue growing in summer. The effluent pH, TSS, COD,BOD5, TKN and TP concentrations were in compliance with both irrigation reuse and discharge regulations.

Comparing the effect of carbon media on nutrient removal and greenhouse gas production in laboratory-scale bioreactors

Abstract The performance of locally available agricultural carbon media (barley straw and hemp straw) was compared to woodchips for removing nitrate (NO3-N) and orthophosphate (PO4-P) in up-flow laboratory bioreactors. These media were tested in three replicates to quantify variability. The production of greenhouse gases nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) were quantified. Influent water with NO3-N and PO4-P flowed continuously through bioreactors at a 4-h hydraulic retention time at 20 °C for 16 weeks. Nitrate removal reached up to 37% across all carbon media after the fifth week, with a removal rate of 64 g N m−3 d−1. Nitrate removal was affected by the type of carbon media in the order of barley straw > hemp straw > woodchips (P < 0.05). Most of the PO4-P rates declined rapidly after the first week for all carbon media meaning none were superior. Greenhouse gas production was dominated by CO2 with less CH4 and N2O produced. Production of N2O relative to nitrate removal for the three media remained low at 0.16 to 0.75%. The findings suggest that agricultural residues could perform better than woodchips for NO3-N removal although there was slightly higher N2O and CO2 production for these residues than woodchips.

Evaluation of Biochar as an Amendment for the Removal of Metals, Nutrients, and Microplastics in Bioretention Systems

Evaluation of Biochar as an Amendment for the Removal of Metals, Nutrients, and Microplastics in Bioretention Systems

Natural Moroccan bentonite clay as an adsorbent for nutrient removal from synthetic leachate: Performance and evaluation

To ensure the protection of public health and environmental integrity, while also meeting effluent regulation standards, it is critical to treat leachate due to its composition of hazardous substances before it is introduced into the environment. Pollution from leachate is characterized by several indicators, including COD, BOD5, conductivity, pH, and the presence of various ions such as ammonium, nitrite, nitrate, chloride, and orthophosphate. This research examines the adsorption properties of natural bentonite clay from Nador, located in eastern Morocco, for its efficacy in removing ammonium, nitrate, and nitrite ions from synthetic leachates. We present the outcomes of adsorption experiments utilizing bentonite clay to eradicate these nitrogen-based ions from artificial leachate, using UV adsorption spectroscopy for the measurement of ion concentrations before and after adsorption. Additionally, the study evaluates the efficiency of bentonite clay in adsorption, identifying the optimal amount of clay required for effective pollutant reduction. Our results demonstrate that, following a 24-hour mixing period, the adsorption rates for ammonium, nitrate, and nitrite ions were roughly 48%, 40%, and 85% at 35 °C, and 40%, 15%, and 25% at 25 °C, respectively. These findings suggest that modulation of agitation duration and temperature can significantly improve adsorption efficiency, with elevated temperatures facilitating shorter reaction times and higher adsorption rates for nitrogen ions. Ultimately, the research confirms the potential of bentonite clay as an effective medium for the removal of these contaminants from landfill leachate, offering a promising approach for enhancing environmental sustainability.

Operation and Performance of The Lab and Pilotscale Greywater Treatment Systems: Biochar and Gravel Use in South Africa

Water security in South Africa depends on natural and artificial water sources such as rivers, lakes, rainwater harvesting, boreholes, dams, desalination, the importation of water from nearby countries, and wastewater treatment plants. The primary input to these water resources is rainfall which is estimated to be around 492 mm per year and is half of the world average (985 mm per year) due to climate change impacts. This study encourages the treatment and reuse of greywater as an additional water source for non-potable purposes such as toilet flushing and irrigation. The performance of the Laboratory (Lab)-scale Gravel Filter Towers (GFTs) was evaluated concurrently with the Pilot-scale system for remediation of the microbiological and physicochemical constituents in greywater which was sampled from separate single-households for both systems. The highest removal efficiency of faecal coliforms by the GTFs was 92.89 ± 93.39 % while the Pilot-scale exhibited a removal efficiency of 21.51 ± 12.47 %. The systems showed partial removal of microbiological, chemical, nutrient, and physical constituents, indicating that further analysis and improvements are required before decentralization. The GFTs could be improved by the addition of a biochar filter while the pilot-scale systems require fresh treatment materials monthly to avoid clogging and leaching of biofilms to the final collection tank. Further analysis could involve the profiling of the microbial communities using metagenomic techniques which may provide insight into the biochemical functioning (bioremediation, quorum sensing, and pathogenicity) of the system.