High Concentrations Of Suspended Solids Research Articles

A novel chitosan and polyferric sulfate composite coagulant for biogas slurry pretreatment by simultaneous flocculation and floatation: Performance and underlying mechanisms

Biogas slurry from anaerobic digestion is rich in active nutrients but has not been fully utilized due to a high content of suspended solids (SS) causing clogging during agricultural irrigation. This study aimed to evaluate the performance of a novel chitosan and polyferric sulfate (CTS-PFS) composite coagulant for simultaneous flocculation and floatation to enhance SS removal while preserving nutrients in biogas slurry. Orthogonal method was used for experimental design to determine the optimal synthesis and operational conditions of CTS-PFS. Results show that CTS-PFS outperformed individual CTS and PFS coagulant in terms of SS removal and nutrient (nitrogen, phosphorus, and potassium) preservation. Compared to individual CTS and PFS coagulation, the combination of CTS and PFS at the mass ratio of 1:6 showed significantly higher performance by 41.5% increase in SS removal and 5.2% reduction in nutrient loss. The improved performance of CTS-PFS was attributed to its formation of polynuclear hydroxyl complexes with ferric oxide groups (e.g. Fe-OH, Fe-O-Fe, Fe-OH-Fe and COO-Fe) to strengthen charge neutralization and adsorption bridging. Data from this study further confirm that CTS-PFS enhanced the removal of small suspended particles and dissolved organic matter in the molecular weight range of 0.4 – 2.0 kDa and preserved ammonia and potassium better in biogas slurry. Bubbles were generated as hydrogen ions from coagulant hydrolysis interacted with bicarbonate and carbonate in biogas slurry for removing the produced flocs by floatation. Floc flotation was more effective in CTS-PFS coagulation due to the significant production of uniform bubbles, evidenced by the reduction in the viscosity of biogas slurry.

Evaluating Relationship between Surface Water Quality and Zooplankton Diversity in Coastal Areas of Tien Giang Province, Vietnam

The zooplankton diversity is the most important ecological parameter for water quality assessment, as these small creatures are sensitive to any changes in water quality, hence the objective of this study as to evaluate the relationship between surface water quality and zooplankton diversity in the coastal areas of Tien Giang province, Vietnam using appropriate standard methods. The results showed that the coastal water quality had high concentrations of suspended solids, ammonium and coliforms. A total of 71 zooplankton species with a total density ranging from 3,219,383 to 24,993,634 individuals/m3 were identified. Among the zooplankton species, Copepoda nauplius appeared at all monitoring stations, predominating with a density ranging from 740,800 to 7,555,250 individuals/m3. The values of the Shannon-Wiener diversity index (H') ranged from 1.54 to 2.37, reflecting the coastal water quality in the study area from polluted to mildly polluted. The coastal water variables of pH, salinity, DO, NH4+-N and coliform were closely correlated with the density of zooplankton species. The relationship between surface water quality and zooplankton diversity could be a basis for selecting biological indicators to monitor coastal water quality.

Effect of suspended solids from anaerobic digested wastewater on performance and microbial community of autotrophic nitrogen removal process

Most anaerobically digested wastewaters have high concentrations of suspended solids, while little is known about whether they adversely affect the performance of the autotrophic nitrogen removal process. In this work, using air-lift internal circulation reactor we studied the effect of suspended solids on the autotrophic nitrogen removal process by adding 600–900 mg/L suspended solids from digested swine wastewater to the influent (R–SS). The results showed that during the formation of autotrophic nitrogen removal granular sludge, suspended solids containing Ca, Mg, Cu P, and Pb can enter the granular sludge, occupy the ecological niche of anammox bacteria, lead to loose internal structure, and damage the internal anoxic environment. It then reduces the settling performance in the R–SS, causes heavy wash-out of granular sludge from the R–SS reactor (2.5 times more than the control, R–CK), and finally reduces the maximum nitrogen removal rate of the autotrophic nitrogen removal process from 5.16 kg N/m3/d to 4.31 kg N/m3/d. Meanwhile, the metagenomic analysis showed that suspended solids reduce the relative abundance of reads from key nitrogen genes of anammox bacteria yet increases reads from both nitrite-oxidizing and denitrifying bacteria, especially nir and nor genes. Further analysis of 16 highly abundant genomes assembled via metagenomics showed that suspended solids decrease the relative abundance of Kuenenia_seed103, an anammox bacterium, from 13.36% (R–CK) to 11.03% (R–SS). Since suspended solids can act as a carbon source for denitrifiers to compete with nitrite or nitric oxide with anammox bacteria, the denitrifier community has progressed from a simple denitrifier consisting of only one or two denitrification steps (nar or nos) that acts as an ammonia and nitrite sink to a complete one that directly reduces nitrite to nitrogen gas. This study will lay a good foundation for its application in wastewater treatment.

Enhanced Pretreatment of Natural Rubber Industrial Wastewater Using Magnetic Seed Coagulation with Ca(OH)2

The efficiency of magnetic seed coagulation (MSC) with pH adjustment by NaOH and Ca(OH)2 as a pretreatment for high-strength natural rubber industrial wastewater (NRIWW) was compared in this study. The high content of suspended solids (SSs) and other inhibitory substances of NRIWW is a primary issue which affects its subsequent secondary and tertiary treatment processes. The MSC process with polyaluminum chloride (PAC), anionic polymer (polyacrylamide—PAM)), and magnetic seeds (MS) (ferric oxide (Fe3O4)) was proven to be a cost-effective pretreatment of NRIWW, and Ca(OH)2 showed improved pretreatment performance, with turbidity, COD, and TSS removals of 95%, 56%, and 64%, respectively. Sedimentation was enhanced from 30 min by conventional coagulation to less than 5 min by the MSC. The organic components of NRIWW reacted with MS to generate Fe–OH/Fe–OH+ linkages through processes of surface complexing and hydrogen bonding. According to fractal analysis, the MSC process optimized with Ca(OH)2 produces less complex flocs that are uniform and densely packed. Additionally, MS served as an adsorbent and promoted the development of magnetic flocs by boosting their density and size. MSC with pH adjustment by Ca(OH)2 presents a robust and cost-effective pretreatment process for NRIWW.

Bioactive carbohydrate from potato peels: A sweet inducer that mediate resistance against powdery mildew disease of cucumber through phytohormonal alterations

Large volumes of nutritive wastes are generated by food industries, which can be used in the production of bioactive compounds of commercial values. The waste generated by potato chips industries contains high quantities of insoluble starch, high concentrations of total suspended solids and chemical oxygen demand, or environmental issues. In this study, the starch extracted from the potato peels was subjected to bioconversion of isomaltose-oligosaccharide by enzymatic method and further eluted isomatlose by liquid chromatography-mass spectrometry. The structural elucidation of isomaltose was confirmed by 1H NMR and 13C NMR spectroscopy. The purified isomaltose displayed excellent in vitro antifungal action against Erysiphe cichoracearum and Fusarium oxysporum at concentrations 1.0 and 2.5 mg/ml, respectively. Notably, cucumber-seeds primed with isomaltose (2.5 and 5.0 mg/mL) concentrations recorded a significant improvement of germination (91.5 and 89 %) and vigor (2210.93 and 2015.7) over the untreated control. Subsequently, the isomaltose-primed cucumber plants challenged with powdery mildew pathogen showed enhanced protection of 63% in comparison with pathogen alone-induced plants. This enhanced growth parameters and induced resistance in cucumber may be fairly contributed by the upregulation of phytohormone levels in primed plants observed in this study. Taken together, this study is unique in the use of bioactive isomaltose from potato peels, which could enable us to minimize the agro-industrial wastes and most importantly could help to develop new formulations for sustainable crop protection strategies.

A novel approach for purifying food waste anaerobic digestate through bio-conditioning dewatering followed by activated sludge process: A case study

Although anaerobic digestion is the mainstream technology for treating food waste (FW), the high pollutant concentration in the resultant food waste anaerobic digestate (FWAD) often poses challenges for the subsequent biochemical treatment such as activated sludge process. In this study, taking a typical FW treatment plant as an example, we analyzed the reasons behind the difficulties in treating FWAD and tested a novel process called as bio-conditioning dewatering followed by activated sludge process (BDAS) to purify FWAD. Results showed that high concentrations of suspended solids (SS) (16439 ± 475 mg/L), chemical oxygen demand (COD) (24642 ± 1301 mg/L), and ammonium nitrogen (NH4+-N) (2641 ± 52 mg/L) were main factors affecting the purification efficiency of FWAD by the conventional activated sludge process. By implementing bio-conditioning dewatering for solid-liquid separation, near 100% of SS and total phosphorus (TP), 90% of COD, 38% of total nitrogen (TN), and 37% of NH4+-N in the digestate could be effectively removed or recovered, consequently generating the transparent filtrate with relatively low pollution load and dry sludge cake (<60% of moisture content). Furthermore, after ammonia stripping and biochemical treatment, the effluent met the relevant discharge standards regulated by China, with the concentrations of COD, TN, NH4+-N, and TP ranging from 151 to 405, 10–56, 0.9–31, and 0.4–0.8 mg/L, respectively. This proposed BDAS approach exhibited stable performance and low operating costs, offering a promising solution to purify FWAD in practical engineering and simultaneously realize resource recovery.

Towards better differentiation of archaeological objects based on geomorphometric features of a digital elevation model, the case of the Old Oder Canal

AbstractLimited visibility in the underwater environment often restricts opportunities for archaeological prospection. Especially in reservoirs with a high content of suspended solids, methods based on acoustics prove to be extremely useful. This study represents the first high‐resolution acoustic mapping and archaeological prospections of the Old Oder Canal, which has extremely poor visibility. The study site is located near the town of Krosno Odrzańskie in Poland. The town is one of the country's most significant river crossings and settlements of mediaeval origin (including its wooden bridges). The following research objectives were identified: (1) exploration of the Old Oder Canal, including underwater acoustics and archaeological prospections; (2) analysis and interpretation of the study area based on acquired datasets; and (3) evaluation of secondary features of the river bathymetry for identification of archaeological objects. Possible locations of archaeological objects were determined based on analysis and interpretation of multibeam echosounder measurements of the riverbed. Fieldwork allowed structural elements of mediaeval bridges to be found and dendrochronological sampling performed. Feature selection analyses allowed the determination and evaluation of geomorphometric attributes, combining the characteristics of the discovered objects and diagnostics in order better to differentiate archaeological remains. Proposed secondary features may facilitate archaeological explorations in difficult environments.

Research progress of leachate treatment in waste transfer station

The garbage leachate generated by the waste transfer station has the characteristics of scattered water sources, relatively small water quantity, large fluctuations in water quality and quantity, and high concentrations of organic matter, ammonia nitrogen, suspended solids, and other pollutants. These characteristics make it prone to environmental hazards. This paper analyzes the characteristics and hazards of leachate from waste transfer stations and introduces the current research status of physico-chemical, biological, and combined treatment of leachate from waste transfer stations. Meanwhile, this paper introduces engineering practices for leachate treatment in waste transfer stations, offering a valuable reference for research and engineering practices in this field. Finally, this review discusses pretreatment, economic, low-carbon, and high-efficiency treatment methods and facilities, the recovery of valuable elements, energy recycling technologies, and the demand outlook for high-standard deep treatment processes.

Analysis of total suspended solids in Lampuuk-Lhoknga Beach Waters, Aceh Besar, Indonesia

Research on total suspended solids in the waters of Lampuuk-Lhoknga Beach, Aceh Besar was conducted on March 16, 2023. Lampuuk-Lhoknga Beach is a beach that has high activity that affects the concentration level of total suspended solids which becomes a problem for waters if the concentration level is high. This study aims to analyze and calculate the concentration of total suspended solids in the waters of Lampuuk-Lhoknga Beach. This study used purposive sampling method by taking beach water samples from several predetermined stations. Water samples that have been taken are analyzed using the gravimetric method. Based on the results of the study, the concentration of total suspended solids at 10 stations (the northernmost, Station 1 to the southernmost, Station 10) ranged from 100 mg/l to 1500 mg/l. The lowest concentration result was found at Station 4 near the cliff, which was 100 mg/l, while the highest result was found at Station 5 near tourism activities, which was 1500 mg/l. The high concentration of total suspended solids is thought to be caused by high human activity in all fields ranging from marine tourism, culinary areas to industrial areas.

Applications of Fenton Coagulation for wastewater treatment: a review

The most diverse forms of pollution and contamination, especially from the industrial sector, reinforce the need to optimize industrial processes in the search for reducing waste generated or even creating and improving appropriate techniques for removing organic compounds in solid waste and effluents. Wastewater resulting from chemical processes, in general, has a complex composition and causes environmental problems when not treated appropriately. An efficient proposal for the treatment of effluents of high chemical complexity and high concentration of suspended solids is Fenton Coagulation. This process reconciles the coagulation process with iron ions and reuses the residual iron concentration to apply a subsequent treatment, the Fenton process. Therefore, the objective of this work is to address the hybrid Fenton coagulation process and discuss important aspects of its use for the treatment of effluents.

INVESTIGATION ON PHYSICOCHEMICAL AND MICROBIOLOGICAL POLLUTION LOAD OF HUDIARA DRAIN AND ITS SUBSIDIARIES/

Majority of Industrial wastewater, both treated and untreated is being pumped into drains in Lahore; mainly converging to Hudiara drain. The same is already polluted when it enters Pakistan’s boundary by wastewater from India and as it passes through Lahore, it’s pollution levels are magnified by addition of mainly Charrar &amp; Sattukatla Drain. In this study we performed weekly complete analysis of some Physicochemical and microbiological analysis of Hudiara drain on point of entry in Pakistan as well as the same for Charrar &amp; Sattukatla Drains. It was observed that the organic loading of wastewater has increased 2-3 times in the last 10 years with maximum values of 1,406 and 413 mg/L obtained respectively. Major factor is the high concentration of suspended solids which ranged from 280 to 701 mg/L as well as high organic decomposition indicated by sulphides upto 23.85 mg/L. Moreover, the baseline pollution load of Hudiara Drain entering Pakistan as well as the pollution load our Industries and Adjacent canals exert directly and indirectly into Hudiara Drain.

Biological Responses of Oyster Crassostrea gasar Exposed to Different Concentrations of Biofloc

Oysters have the potential to be a part of more sustainable farming systems, such as multitrophic systems integrated into biofloc systems, due to their filtration activity, which enables them to act as organic consumers. However, the stress experienced by animals in a system with a high organic load can compromise their productive performance. The objective of this study was to evaluate the biological responses of Crassostrea gasar oysters when exposed to different concentrations of total suspended solids in biofloc systems. The oysters were exposed to four different concentrations of solids for 28 days. Hall effect sensors were installed on the outside of the shells to detect the movement of the oyster valves. Also, biochemical and histological analyses were conducted to assess the biological responses of the oysters to exposure to varying levels of solids. A difference in valve opening detected by the Hall sensors was observed from the second week of culture, indicating a relationship between shell closure and higher concentrations of suspended solids present in the system. In terms of biochemical analysis, a significant increase in lipid damage was observed in treatments with medium and high levels of total suspended solids compared with the control group. Conversely, no changes were observed in the gill structure of the oysters caused by the concentrations of suspended solids in the system when compared with the control. According to the analyses of gill activity and biochemistry, it is suggested that C. gasar should be cultured with total suspended solids at less than 200 mg/L. Oysters cultivated in a biofloc system keep their shells closed when subjected to high concentrations of total suspended solids; concentrations of total suspended solids below 200 mg/L do not induce oxidative stress, changes in behavior or histological alterations in C. gasar oysters cultivated in a biofloc system.

Pilot study on ceramic flat membrane bioreactor in treatment of coal chemical wastewater

Some toxic and refractory pollutants in coal chemical wastewater can penetrate the biochemical treatment systems and cause high concentrations of suspended solids in the effluent, which may obstruct the subsequent advanced treatment. In this project, a submerged ceramic plate membrane system was integrated to the last oxic corridor of an existing multistage anoxic/oxic tank. In the ceramic flat membrane bioreactor, the influent chemical oxygen demand (COD) was 102.24–178.88 mg/L, with a removal ratio of approximately 30%. The NH3–N concentration in the effluent was relatively stable with an average value of 1.76 mg/L. The turbidity of the effluent was in the range of 0.235–0.852 NTU and was stable below 1 NTU. A flux of 30 L m−2·h−1 could meet the requirements of the pilot test. A gas-water ratio of 50:1 was found optimal. When the concentration of mixed liquor suspended solids (MLSS) was >3769 mg/L, the extracellular polymeric substance in the mixed solution was utilized by microorganisms as a substrate. High MLSS decreased membrane fouling rate. NaClO backwashing can effectively remove pollutants without adversely affecting the treatment efficiency of membrane bioreactors.

Mapping of the Spatial Scope and Water Quality of Surface Water Based on the Google Earth Engine Cloud Platform and Landsat Time Series

Surface water is an important parameter for water resource management and terrestrial water circulation research that is closely related to human production and livelihood. With the rapid development of remote sensing technology and cloud computing platforms, the use of remote sensing technology for large-scale and long-term surface water monitoring and investigation has become a research trend. Based on the Google Earth Engine (GEE) cloud platform and Landsat series satellite data, in this study, the Emergency Geomatics Service (EGS) operational surface water mapping algorithm and water index masking were utilized to extract the spatial scope of the water body. The validated models of the Secchi disk depth (SDD), chlorophyll-a (Chl-a) and suspended solids (SS) concentration were applied to water quality parameter inversion and water quality evaluation. Surface water extent extraction and water quality maps were created to analyze the spatial distribution of the water body and the spatial–temporal evolution characteristics of the water quality parameters. A verification experiment was carried out with the surface water in Zhejiang Province as the research object. The results show that the surface water in the study area from 1990 to 2022 could be accurately extracted. The kappa coefficients were all greater than 0.90, and the overall accuracies of the extractions were greater than 95.31%. From 1990 to 2022, the total surface water area in Zhejiang Province initially decreased and then increased. The minimum water area of 2027.49 km2 occurred in 2005, and the maximum water area of 2614.96 km2 occurred in 2020, with an annual average variation of 193.92 km2. Since 2015, the proportion of high SS and Chl-a concentrations, and low SDD water bodies in Zhejiang Province have decreased, and the proportion with better water quality has increased significantly. The spatial distribution map of the surface water and the inversion results of the water quality parameters obtained in this study provide a valuable reference and guidance for regional water resource management, disaster monitoring and early warning, environmental protection, and aquaculture.

The current state of the Southern Bug River mouth ecosystem

The article considers the pre-war conditions main components of the Southern Bug mouth ecosystem. The results of sediments samples study have shown transformation of lagoonal accumulation, appearance of reducing condition spots in sediments, presence of exceeding MAP for lead. An estuarine water analysis given an idea about hydrochemical features mouth section of river, namely: high concentration of suspended solids – on an average 11,4 mg/dm3; increasable concentration BOD5 – an indicator of easily oxidized organic substances content; periodic significant exceeding MAC of ammonium and nitrite nitrogen. Hydrobiological changes primarily concern a decrease in primary productivity due to a decline in phytoplankton biodiversity; there was also a reduction of zooplankton. The current state of the Southern Bug River mouth ecosystem is formed predominantly under the periodic dredging of shipping channels followed by the formation silt dumps. The post-war revitalization of the Southern Bug estuary ecosystem should include measures to mitigate the negative effects of anthropogenic activity especially the consequences of hydraulic engineering works.

Estimating the concentration of total suspended solids in inland and coastal waters from Sentinel-2 MSI: A semi-analytical approach

Inland and coastal waters provide key ecosystem services and are closely linked to human well-being. In this study, we propose a semi-analytical method, which can be applied to Sentinel-2 MultiSpectral Instrument (MSI) images to retrieve high spatial-resolution total suspended solids (TSS) concentration in a broad spectrum of aquatic ecosystems ranging from clear to extremely turbid waters. The presented approach has four main steps. First, the remote sensing reflectance (Rrs) at a band lacking in MSI (620 nm) is estimated through an empirical relationship from Rrs at 665 nm. Second, waters are classified into four types (clear, moderately turbid, highly turbid, and extremely turbid). Third, semi-analytical algorithms are used to estimate the particulate backscattering coefficient (bbp) at a reference band depending on the water types. Last, TSS is estimated from bbp at the reference band. Validation and comparison of the proposed method with three existing methods are performed using a simulated dataset (N = 1000), an in situ dataset collected from global inland and coastal waters (N = 1265) and satellite matchups (N = 40). Results indicate that the proposed method can improve TSS estimation and provide accurate retrievals of TSS from all three datasets, with a median absolute percentage error (MAPE) of 14.88 %, 31.50 % and 41.69 % respectively. We also present comparisons of TSS mapping between the Sentinel-3 Ocean and Land Colour Instrument (OLCI) and MSI in Lake Kasumigaura, Japan and the Tagus Estuary, Portugal. Results clearly demonstrate the advantages of using MSI for TSS monitoring in small water bodies such as rivers, river mouths and other nearshore waters. MSI can provide more detailed and realistic TSS estimates than OLCI in these water bodies. The proposed TSS estimation method was applied to MSI images to produce TSS time-series in Lake Kasumigaura, which showed good agreements with in situ and OLCI-derived TSS time-series.

Coal mine wastes: Effective mitigation of coal waste slurry and acid mine drainage through bioflocculation using mixotrophic bacteria as bioflocculants

Acid mine drainage (AMD) and coal waste slurry, byproducts of global mining and coal processing activities, represent significant environmental pollution concerns due to their acidic nature and high total suspended solids (TSS) content. The exploration of microbial treatment methods, specifically the utilization of microorganisms and their metabolic byproducts as bioflocculants, is underway to mitigate the adverse effects of these byproducts. This investigation assessed the effectiveness of 54 mixotrophic bacterial strains in treating coal waste slurry and AMD from coal mines located in Kalimantan, Indonesia. The bacterium Citrobacter freundii (strain SKC-4), cultured in SKC1 medium (comprising 225 mL of seawater from the Java Sea and 15 g/L molasses), demonstrated superior performance, reducing the TSS value from 4998.20 ppm to 16 ppm within an hour. Fourier Transform Infrared (FTIR) analysis revealed an increase in the intensity of the CO and CN groups from protein amides and CH2 from carbohydrates, suggesting an interaction between bacteria and clay minerals in the coal waste slurry. The bacteria also played a crucial role in adjusting the pH of AMD, elevating it from 3.82 to 6.07 after one hour of conditioning with a bacterial culture to AMD ratio of 1:9. The interaction between bacteria and their metabolic products was further substantiated by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, which detected the presence of an extracellular polymeric substance (EPS). To our knowledge, this study represents the first exploration of the potential of mixotrophic bacteria as bioflocculants in the biotreatment of coal waste slurry and AMD from coal mining operations.

Sustainable use of wastes as reactive material in permeable reactive barrier for remediation of acid mine drainage: Batch and continuous studies

The aim of this work was to evaluate the feasibility of the use of different industrial and agricultural wastes as reactive materials in Permeable Reactive Barriers (PRB) for Acid Mine Drainage (AMD) remediation. Sugar foam (SF), paper mill sludge (PMS), drinking water sludge (DWS) and olive mill waste (OMW) were evaluated in terms of pH neutralization and metal removal from AMD. Laboratory batch tests and continuous pilot scale up-flow columns containing 82% of Volcanic Slag (VS), as porous fill material, and 18% w/w of one of the industrial and agricultural wastes previously indicated, were tested.From the batch tests it was observed that the reactive material presenting the best results were the SF and the PMS. The results obtained in all the PRB were accurately described by a pseudo-first order model, presenting coefficient of determination higher than 0.96 in all the cases.During the continuous operation of the PRB, the porosity and hydraulic retention time (HRT) of most of the up-flow columns strongly decreased due to chemical precipitation and biofilm growth. The SF presented a significant number of fine particles that were washed out by the liquid flow, generating an effluent with very high total suspended solid concentration. Despite SF was the material with the highest alkalinity potential, the reduction of the HRT limited its neutralization and metal removal capacity. PMS and DWS presented the best pollutant removal yields in the continuous operation of the PRB, ranging from 55 to 99% and 55–95% (except in the case of the Mn), respectively. These results allowed the metal removal from the AMD. Additionally, these wastes presented very good biological sulphate reduction.Based on these results, the use of PMS and DWS as reactive material in PRB would allow to simultaneously valorise the industrial waste, which is very interesting within the circular economy framework, and to remove metals from the AMD by means of a low-cost and environmentally sustainable procedure.

Enhancement of nutrient removal in an activated sludge process using aerobic granular sludge augmentation strategy with ammonium-based aeration control

To enhance nutrient removal from low-strength municipal wastewater in a continuous-flow activated sludge (CFAS) process using aerobic granular sludge (AGS) augmentation strategy, a pilot-scale demonstration was configured with a mainstream reactor (anaerobic/aerobic process) and a sidestream sequencing batch reactor for AGS production. The aeration of the mainstream reactor was controlled based on dissolved oxygen (DO) and ammonium concentrations during Phases I and II–III, respectively. During Phase III, an anoxic zone was created in the mainstream aerobic tank. Throughout the demonstration period, excellent sludge settleability in the mainstream reactor (SVI30 ≤ 80 mL g−1) under long sludge retention time conditions (≥12 d) allowed the maintenance of a high mixed liquor suspended solids concentration (≥3000 mg L−1). The total nitrogen (TN) removal ratio improved significantly during Phases II and III (49.3 ± 4.1% and 50.1 ± 10.2%, respectively) compared to Phase I (43.2 ± 5.5%). Low DO concentration (< 0.5 mg L−1) by the ammonium-based aeration tended to increase the simultaneous nitrification and denitrification efficiency (> 40%), enhancing TN removal (> 50%). The reduction of DO and nitrate concentrations in the returning sludge liquor can stabilize phosphorus removal (approximately 80% of the 25th percentile). In addition, the aeration efficiency during Phase III decreased by 26–29% compared to Phase I. These results suggest that the introduction of ammonium-based aeration control to the CFAS using the AGS augmentation strategy could contribute to superior sewerage treatment, including nutrient removal and a low carbon footprint.

Development and substantiation of an improved version of a main drainage facility classical scheme at a kimberlite mine developed by block caving method

Evidence demonstrates that as the production capacity of a kimberlite mine increases, there is a corresponding increase in the volumetric concentration of suspended solids in the mine water extracted from its watercollecting workings. The Udachny mine, known for its high productivity in comparison to other domestic kimberlite mines, experiences a higher concentration of suspended solids in the mine waters, leading to significant sludge settling within the primary drainage facility’s water-collecting workings. This determinal effect adversely affects the operational efficiency of pumping equipment and the reliability of LHDs. To address these issues, an enhanced version of the conventional main drainage facility scheme, specifically designed for kimberlite mine utilizing the block caving method, is proposed. This modified scheme aims to provide improved clarification of the mine water in the water-collecting workings and facilitate more efficient dewatering of the settled slurry sludges. Furthermore, a methodology has been developed to determine the time required for slurry sludge removal, the sedimentation characteristics of the solid phase, and the rheological properties of the liquid phase of the mine water.