Suspended Solids Research Articles

Increasing biomass concentration facilitates simultaneous nitrogen removal and sludge reduction under low C/N conditions

To overcome the issues of limited carbon source and high sludge production in partial denitrification/anammox (PD/A) process, the effects of mixed liquor suspended solids (MLSS) and carbon/nitrogen ratio (C/N) on PD/A were investigated through parallel experiments. Nitrogen removal efficiencies decreased significantly when C/N was reduced (1.5 → 0.75). When MLSS was doubled, the nitrogen removal efficiencies in the two parallel reactors increased from 75.3 %, 72.9 % to 86.9 %, 89.7 %, respectively, and sludge yields decreased obviously. Combining with in-situ test, it was speculated when MLSS increased, fermentation was enhanced, providing substrate for partial denitrification. Thauera, involved in partial denitrification, decreased obviously with reduced C/N, but increased from 9.93 % to 38.16 % when MLSS doubled, which could promote the PD/A process. Terrimonas and Ignavibacterium (fermentative bacteria) increased from 1.26 %, 5.22 % to 6.62 %, 6.30 %, respectively. These results proved that increasing MLSS under low C/N ratios promoted fermentation in PD/A system, facilitating efficient nitrogen removal and sludge reduction.

Efficient Pulp and Paper Wastewater Treatment Using Green Tea-Synthesized Magnetite: Artificial Intelligence and Kinetic Analysis

The pulp and paper industry generates pollutant-laden wastewater, requiring effective treatment to prevent environmental damage and enable sustainable reuse. This study investigated the use of green tea-synthesized magnetite (GT-Fe3O4) for treating pulp and paper wastewater. Characterization techniques, including SEM, XRD, FTIR and EDX, were employed to analyze the synthesized magnetite. Batch adsorption studies were conducted to examine the optimal operating conditions, including pH, contact time, adsorbent dose, and stirring rate, for achieving the best treatment performance. The treatment focused on reducing chemical oxygen demand (COD), total suspended solids (TSS), and turbidity in the wastewater. The adsorption data were evaluated using kinetic models, with the pseudo-second-order model providing the best fit. Additionally, an artificial intelligence prediction model (AIP) with a 4–10–1 structure was employed to predict the removal efficiencies. The optimal conditions for the treatment process were determined to be a pH of 6, a contact time of 60min, a GT-Fe3O4 dose of 0.7g/L, and a stirring rate of 150rpm at room temperature. Under these conditions, the removal efficiencies for COD, TSS, and turbidity were 70.5%, 65.4%, and 38.8%, respectively. The AIP model achieved an R² value range of 0.978 to 0.982, showing high prediction accuracy. The study demonstrates that GT-Fe3O4 effectively reduces pollutants in pulp and paper wastewater.

How Does Triclocarban Affect Sulfur Transformation in Anaerobic Systems?

Triclocarban (TCC), as a typical antimicrobial agent, accumulates at substantial levels in natural environments and engineered systems. This work investigated the impact of TCC on anaerobic sulfur transformation, especially toxic H2S production. Experimental findings revealed that TCC facilitated sulfur flow from the sludge solid phase to liquid phase, promoted sulfate reduction and sulfur-containing amino acid degradation, and largely improved anaerobic H2S production, i.e., 50-600 mg/kg total suspended solids (TSS) TCC increased the cumulative H2S yields by 24.76-478.12%. Although TCC can be partially biodegraded in anaerobic systems, the increase in H2S production can be mainly attributed to the effect of TCC rather than its degradation products. TCC was spontaneously adsorbed by protein-like substances contained in microbe extracellular polymers (EPSs), and the adsorbed TCC increased the direct electron transfer ability of EPSs, possibly due to the increase in the content of electroactive polymer protein in EPSs, the polarization of the amide group C═O bond, and the increase of the α-helical peptide dipole moment, which might be one important reason for promoting sulfur bioconversion processes. Microbial analysis showed that the presence of TCC enriched the organic substrate-degrading bacteria and sulfate-reducing bacteria and increased the abundances of functional genes encoding sulfate transport and dissimilatory sulfate reduction.

Influence of various carbon and nitrogen ratios in a jaggery-based biofloc rearing system on the Asian stinging catfish Heteropneustes fossilis

Biofloc technology (BFT) is becoming popular in aquaculture. As the human population has rapidly increased, so has the demand for protein, driving the expansion of aquaculture. The increased use of aqua medicines in aquaculture has led to resistant microbes. BFT offers a promising, eco-friendly solution by promoting beneficial microbes to improve fish health and reduce chemical use, supporting the industry's long-term sustainability. BFT recycles waste without water exchange by maintaining an optimal carbon-nitrogen (C:N) ratio and adding an external carbon source, which promotes the growth of heterotrophic bacteria and other essential microbes that absorb ammonia from feed and waste, forming beneficial microbial aggregates. This study evaluated the effects of various C:N ratios in a jaggery-based BFT system on water quality, growth, feed efficiency, and the well-being of Heteropneustes fossilis. A completely randomized design with triplicates (2.33 kg/m³ in 1500 L tanks) was used to compare a control group without biofloc to three BFT treatments with C:N ratios of 8:1 (CN8), 12:1 (CN12), and 16:1 (CN16) over 180 days. Daily feeding was conducted at 5–2 % of the fish's body weight (initial weight of 5.0±0.5 g). Higher C:N ratios were linked to reduced dissolved oxygen, ammonia, and nitrite levels, alongside increased total suspended solids, floc volume, and heterotrophic bacteria counts, while the CN12 had the highest levels of beneficial microbes (Firmicutes and Actinobacteria), leading to superior fish growth, survival, and biomass compared to CN8 and CN16. The CN12 also showed better stress response, hematology, immunity, and antioxidant properties. Histologically, fish in CN12 and CN8 had healthier liver and intestines compared to CN16 and control. The results suggest that a C:N ratio of 12:1 was optimal for biofloc systems used in cultivating H. fossilis, enhancing both microbial growth and water quality.

Assessing the nutrient removal performance from rice-crayfish paddy fields by an ecological ditch-wetland system

Agricultural drainage from catchments significantly impacts aquatic ecosystems due to high nitrogen and phosphorus concentrations in runoff. While original ecological ditches and wetlands have demonstrated effectiveness in nutrient load removal, the overall impact of an ecological ditch-wetland system (EDWS) on agricultural nutrient removal has received limited attention. This study conducted a field experiment to investigate the physicochemical conditions and nutrient removal efficiency of an EDWS for purifying nutrient discharge from rice-crayfish paddy fields. Variations in water temperature (WT), dissolved oxygen (DO), pH, and total suspended solids (TSS) within the EDWS were assessed. Nutrient concentrations—including total nitrogen (TN), ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), total phosphorus (TP), and soluble reactive phosphorus (SRP)—were monitored from the tillering to the ripening stage of the rice growth cycle. The evaluation of nutrient removal efficiencies in the EDWS revealed that ecological ditches exhibited higher removal efficiencies compared to wetlands. The average total removal efficiencies for TN, NH4-N, NO3-N, TP, and SRP were 37.50 %, 39.38 %, 38.62 %, 37.94 %, and 39.51 %, respectively, with peak removal efficiencies observed at specific growth stages of the rice crop. Furthermore, the study explored the influence of hydraulic retention time on nutrient removal efficiency in the EDWS, indicating higher nutrient discharge removal efficiencies under low water discharge rates. Linear regression analysis identified water discharge, influent nutrient loads, and TSS as significant factors affecting nutrient removal efficiency in the EDWS. This study provides valuable insights into the effectiveness of EDWS in purifying nutrient discharge from rice-crayfish paddy fields, highlighting their potential as sustainable solutions for nutrient management in agricultural landscapes.

Assessment of the efficiency of wastewater treatment from coal enterprises for suspended solids using various filtering materials

Assessment of the efficiency of wastewater treatment from coal enterprises for suspended solids using various filtering materials

Performance evaluation of a wastewater treatment plant from a dairy in the state of Minas Gerais, Brazil: a case study.

Wastewater generated in dairies has a strong polluting potential and must be treated for disposal into water bodies or reuse. The objective of this work was to analyze the efficiency of removing pollutants through the processes used by a wastewater treatment plant (WWTP) of a dairy located in the state of Minas Gerais, Brazil. For this purpose, the results of the characterization analyses referring to raw and treated wastewater were interpreted. The results showed that the sequence of processes used in the WWTP (water/oil separation, dissolved air flotation, followed by biodegradation in an upflow anaerobic filter) is efficient in removing on average 99.1% of COD and 98.7% of BOD5. For treated wastewater, data on pH and concentration of total suspended solids, total ammoniacal nitrogen, surfactants, settleable solids, and oils and greases also met the standards for disposal into water bodies. For reuse in agriculture, treated wastewater can be used for irrigation, but it is recommended to additionally evaluate the Escherichia coli parameter. When evaluating the existence of linear correlation between COD and BOD5 data, it was possible to find only a moderate correlation (R2 equal to 0.7) for treated wastewater.

Sustainable treatment of combined industrial wastewater: synergistic phytoremediation with Eichhornia crassipes, Pistia stratiotes, and Arundo donax in biofilm wetlands

This study investigates the treatment of combined wastewater from Hattar Industrial Estate using Biofilm Wetlands (BW) planted with monoculture species: Eichhornia crassipes (EAC), Pistia stratiotes (WL), and Arundo donax (GR). Each species showed distinct capabilities in organic degradation, metal uptake, and pH stabilization. BW2, planted with EAC, achieved the highest total solids (TS) and total suspended solids (TSS) removal efficiencies of 66% and 65%, respectively. GR effectively reduced initial COD concentrations from 232 mg/L to 58.67 mg/L, while EAC and WL reached reductions to 72.78 mg/L and 70.67 mg/L, respectively. Overall, the plant efficiency ranking was EAC > GR > WL. These findings underscore the potential of these plant species in synergistic BW systems, highlighting their role as natural solutions for remediating complex industrial effluents. This research contributes to advancing eco-friendly wastewater treatment approaches, suggesting promising applications for sustainable practices in industrial contexts. RESEARCH HIGHLIGHTS This research assessed the effectiveness of phytoremediation using Eichhornia crassipes, Pistia stratiotes, and Arundo donax for removing pollutants i.e. heavy metals (Cd, Pb, Ni, K, Ca, Mg, Na, Fe, Hg) nitrates, phosphates and sulfates from combined industrial wastewater of Hattar Industrial Estate Pakistan. It highlighted the potential of selected plant species’ as natural treatment systems, providing crucial insights into their efficiency. Findings contribute to understanding nature-based solutions for complex industrial effluents.

POLLUTION OF THE FIFTH CANAL ON THE CRNA RIVER IN THE REGION OF BITOLA

Water is an irreplaceable natural resource. The main goal of this research is to see the pollution of the fifth canal on Crna River in the region of Bitola. As measuring points for sampling for this analysis are: measuring point 1 (Crna River near the village of Novaci), measuring point 2 (fifth canal exit of Bitola), measuring point 3 (fifth canal near the village of Kravari) measuring point 4 (fifth canal before flowing into the Crna River), measuring point 5 (Crna River before being mixed with water from the fifth canal), measuring point 6 (Crna River after mixing with water from the fifth canal) and measuring point 7 (Crna River near the village of Skocivir). Water samples were taken in May and November. To determine the water quality, the following physicochemical parameters were made: turbidity (by turbidimeter), suspended solids, total organic carbon, biological oxygen demand, and dissolved oxygen (determined with UV pastel). From the results, it has been concluded that the highest pollution is in the fifth channel, measuring point 2 for the following parameters in May: turbidity (35.3 mg/L), total organic carbon (210.8 mg/L), suspended solids (77.5 mg/L, and in November164.0 mg/L). Of the measuring points of Crna River, the highest pollution is in measuring point 6 in November: biological oxygen demand (14.5 mg/L), and total organic carbon (13.7 mg/L). That is why it is suggested to purify the wastewater before it is released into the rivers.

Performance of a novel Built-in Static Magnetic Field – Biological Aerated Filter (BSMF–BAF) for treating high-salt textile dyeing wastewater

High-salt textile dyeing wastewater is difficult to treat. Magnetic fields can enhance the biodegradation capacity and extreme environmental adaptabilities of microorganisms. Thus, magnetically enhanced bioreactors are expected to improve the treatment efficiency and stability of high-salt textile dyeing wastewater. Accordingly, a novel Built-in Static Magnetic Field – Biological Aerated Filter (BSMF–BAF) was constructed and investigated for treating actual high-salt textile dyeing wastewater in this study. Two other BAFs packed with traditional and magnetic ceramsite carriers, respectively, were simultaneously operated for comparison. The removal of color, chemical oxygen demand (COD), suspended solid (SS) and acute toxicity were monitored. The activities of key enzymes and microbial community structure were analyzed to reveal possible mechanisms for improving the treatment efficiency of traditional BAF using the BSMF. The results showed that the BSMF–BAF possessed the highest removal efficiencies of color, COD, SS and acute toxicity among the three BAFs. The BSMF induced significant increases in the activities of azoreductase and lignin peroxidase, which were responsible for the degradation of azo compounds in the wastewater and the detoxification of toxic intermediates, respectively. Additionally, the BSMF induced the relative enrichment of potentially effective bacteria and fungi, and it maintained a relatively high abundance of fungi in the microbial community, resulting in a high treatment efficiency.

Environmental factors that regulate Vibrio spp. abundance and community structure in tropical waters

Vibrio spp. is a group of heterotrophic bacteria that are ubiquitous in marine habitats, with various ecological and clinical importance. This study investigated the environmental factors that regulate Vibrio spp. dynamics in various tropical marine habitats, including nearshore (an estuary and a coastal beach) and offshore transects located northwest and southeast of Peninsular Malaysia, while focusing on the distribution of attached and free-living Vibrio spp., population growth, and community composition. The results showed that > 85% of the Vibrio spp. in nearshore waters occurred in attached form and correlated positively to total suspended solids (TSS) and Chlorophyll a (Chl a) concentrations. On the other hand, Vibrio spp. growth rates were positively correlated to dissolved organic carbon (DOC) concentrations, but negatively correlated to total bacterial counts, likely due to resource competition. In addition, high-throughput sequencing of 16S rRNA V3-V4 region showed that Vibrio spp. in these tropical waters contributed < 1 − 18% of the whole bacterioplankton community, and the six major Vibrio spp. taxa were V. alginolyticus group, V. brasiliensis, V. caribbeanicus, V. hepatarius group, V. splendidus group and V. thalassae. db-RDA (cumulative variance explicated = 93.53%) further revealed the influence of TSS, DOC, and dissolved organic nitrogen (DON) to the Vibrio spp. community profiles. The study highlighted the importance of suspended solids (TSS and Chl a) and dissolved organic nutrients (DOC and DON) towards Vibrio spp. dynamics in tropical marine waters.

Integrated treatment of black wastewater using sedimentation, constructed wetland, and nanoparticles coagulation

ABSTRACT The aim of the present investigation was to achieve an efficient treatment for black wastewater for non-restricted reuse. The treatment included sedimentation followed by horizontal flow constructed wetland (HF-CW), and finally chemical coagulation using magnetite (Fe3O4) nanoparticles. For the wetland, the average organic loading rate (OLR) was 42.83 biochemical oxygen demand (BOD)/m2day and 71.30 g chemical oxygen demand (COD)/m2 day, while average surface loading rate was 0.185 m3/m2 day. The obtained results revealed that removal percentage of COD, BOD, and total suspended solids (TSS) by sedimentation followed by processing through wetlands was 80.3, 81.6, and 80%, which corresponds to 76, 42.56, and 54 mg/l, respectively. When magnetite nanoparticles were added to the HF-CW effluent at the optimum dose of 25 mg/l in combination with 10 mg/l FeCl3, the overall removal rate increased to reach 95.9, 99.1, 99.17, 92.3, 94.3, 94.3, and 91.3% for turbidity, COD, BOD, TSS, phosphate (PO4), total nitrogen (TN), and sulfide, respectively. The corresponding residual concentrations were 5 NTU, 8, 5, 18 according to table 3, 0.07, 1, and 1.04 mg/l, respectively. According to the national and international regulations, the present final treated effluent can be safely reused as a non-restricted source for agriculture purposes. The overall results revealed that the implemented study is simple, efficient, reliable, and economical, particularly for remote areas, according to the non-restricted reuse requirements.

Impacts of illegal mining activities on water quality for irrigation and implications for public health: A case study of the Oda River in the Ashanti Region of Ghana

ABSTRACT This study evaluated the biological and physicochemical parameters of the Oda River, including the detection of heavy metals. To achieve this purpose, a quantitative experimental research design was employed. Twenty-four water samples were taken along the Oda River from Obeng ne Obeng, Abuakwaa, and Odaso communities. The samples were analysed in a laboratory, and the results were compared to the irrigation water quality standards from the Food and Agricultural Organization (FAO). The study found that the concentration of turbidity and total suspended solids exceeded the recommended standards of FAO, while the river's pH, electrical conductivity, and total dissolved solids concentrations were within permissible boundaries. Lead, cadmium, mercury, arsenic, and fluoride were present at concentrations lower than the recommended guidelines, whereas copper and cyanide were not discovered. However, iron concentrations exceeded the FAO guidelines. Escherichia coli concentrations in the Obeng ne Obeng were lower than the FAO irrigation standards but were higher in the Abuakwaa and Odaso. The Pearson correlation coefficient highlighted significant correlations between the physicochemical parameters. This paper concludes that unregulated mining activities may endanger vital water resources for irrigation, public health, food safety, ecosystems, and livelihoods.

Septic tanks as a pathway for emerging contaminants to the aquatic environment–Need for alternative rural wastewater treatment?

Septic tanks (STs) as a decentralised approach to community wastewater treatment were investigated as a pathway for emerging contaminants (ECs) entering the aquatic environment. A broad range of ECs were examined in five community STs (population equivalents 217–475) and receiving rivers in Scotland over 12 months. All 68 studied ECs were detected at least once in ST influent or effluent at a broad concentration range from ng L−1 – μg L−1 which can surpass freshwater predicted no-effect concentrations. Pharmaceuticals with acute use, such as antibiotics and antifungals, had high monthly variability and concentrations can exceed those previously found in centralised wastewater treatment works. Differences between the STs demonstrate the impact of localised prescription and population behaviour on EC concentrations. The similarities in concentrations between influent and effluent, suggest limited or no removal of ECs in STs. Hence, dilution of the discharges is required to mitigate environmental risk. Although the contribution of ECs sorbed to suspended solids to the total EC concentration was generally small (<10%), higher contributions (>30%) were observed for fluoroquinolone antibiotics (ofloxacin and ciprofloxacin), antidepressants (fluoxetine), and antifungals (clotrimazole). A wide range of ECs were also detected in rivers upstream and downstream of the ST discharge points, and concentrations increased by up to 95% downstream. In general, risk quotients (RQs) in the rivers were low, indicating small risk for the environment. However, higher RQs (>1) were found for ibuprofen, diclofenac and ciprofloxacin in a few samples. Therefore, reducing their concentration by improving ST performance or through sustainable medicines use may be needed at low dilution locations to mitigate any risk.

Characterization of Silica Sand-Based Pervious Bricks and Their Performance under Stormwater Treatment

The acceleration of urbanization has disrupted natural water cycles, resulting in increased impervious urban surfaces and non-point source pollution from stormwater runoff. Addressing urban stormwater recharge has become crucial. This study introduces a novel silica sand-based permeable filtration material, investigating its surface characteristics, pore structure, permeability, and pollutant interception capabilities. The results demonstrate that hydrophilic binder coating modification of the permeable surface sand aggregate, combined with hydrophilic inorganic additives, having a porous structure with an average pore size of less than 50 μm and a porosity between 15% and 35%, significantly enhances surface hydrophilicity, achieving a permeation rate of up to 6.8 mL/(min·cm²). Moreover, it shows exceptional filtration and anti-clogging properties, achieving over 98% suspended solids interception and strong resistance to fouling. Dynamic biofilm formation experiments using simulated rain and domestic wastewater explore biofilm morphology and function on silica sand filtration well surfaces. Mature biofilms sustain COD removal efficiency exceeding 70%, with levels consistently below 50 mg/L, NH4+ decreasing to 2 mg N/L, and total nitrogen maintained below 10 mg N/L. The system features anoxic, anoxic, and aerobic zones, fostering synergistic organic matter and nitrogen removal by diverse microorganisms, enhancing pollutant mitigation. Silica sand-based permeable filtration material effectively mitigates urban stormwater runoff pollutants—suspended solids, organic matter, and nitrogen—offering an innovative solution for sponge city development and rainwater resource management.

Analysis of wastewater treatment plant data identifies the drivers of PFAS enrichment in foams

The concept of incorporating foam fractionation in aerated bioreactors at wastewater treatment plants (WWTPs) for the removal of per- and polyfluoroalkyl substances (PFAS) has recently been proposed. The extent of PFAS enrichment in aerated bioreactors’ foams, as indicated by enrichment factors (EFs), has been observed to vary widely. Laboratory evidence has shown that factors affecting PFAS enrichment in foams include conductivity, surfactant concentrations and initial PFAS concentrations. However, real wastewaters are complex heterogenous matrices with physical, chemical and biological characteristics potentially contributing to the phenomenon of PFAS partitioning into foams. In this study, we characterised mixed liquor suspensions, including conductivity, filament content, aqueous PFAS concentrations, surface tension and total suspended solids concentrations (TSS) as well as foams, including bubble size and half-life. We used statistical tools – linear mixed-effects model – to establish relationships between PFAS enrichment in aerated bioreactor foams and the examined characteristics. We found that some of the examined characteristics, specifically filament content, surface tension and TSS concentrations measured in mixed liquor suspension and foam half-life, are negatively and significantly associated with the enrichment of longer chain PFAS (with perfluorinated carbon number ≥ 6). Of these, filament content is the important determinant of PFAS enrichment, potentially leading to an increase in, for example, perfluorooctanoic acid (PFOA) EF from 3 to 100 between typical filamentous and non-filamentous suspended biomass. However, enrichment of shorter chain PFAS (with perfluorinated carbon number ≤ 5) is negligible and is not affected by the characteristics that were measured. The findings of our study may serve as valuable information for the implementation of foam fractionation at WWTPs by elucidating the drivers that contribute to the enrichment of longer chain PFAS, under conditions typically found at WWTPs.

Optimization of Recovery of Nutrients from Pig Manure Slurry through Combined Microbial Fuel Cell and Microalgae Treatment

Microbial fuel cells (MFCs) and microalgae–bacteria consortia represent two renewable and promising technologies of growing interest that enable wastewater treatment while obtaining high-value-added products. This study integrates MFCs and microalgae production systems to treat animal slurry, aiming to remove and recover organic and inorganic components while generating energy and producing biomass. The MFCs effectively eliminated Chemical Oxygen Demand (COD), organic nitrogen, and a portion of the suspended solids, achieving a maximum voltage of 195 mV and a power density of 87.03 mW·m−2. After pre-treatment with MFCs, the slurry was diluted to concentrations of 10%, 50%, and 100% and treated with microalgae–bacteria consortia. The results showed a biomass production of 0.51 g·L−1 and a productivity of 0.04 g·L−1·day−1 in the culture fed with 10% slurry, with significant removal efficiencies: 40.71% for COD, 97.76% for N-NH4+, 39.66% for N-NO2−, 47.37% for N-NO3−, and 94.37% for P-PO4−3. The combination of both technologies allowed for obtaining a properly purified slurry and the recovery of nutrients in the form of bioelectricity and high-value biomass. Increasing the concentration of animal slurry to be treated is essential to optimize and scale both technologies.

Performance of Dairy Factory Wastewater Treatment Plant (Case Study of Pasuruan Dairy Factory East Java)

The 'ILP' company produces bottled milk with chocolate, melon, strawberry, and vanilla flavors in colorless HDPE (High-Density Polyethylene) plastic bottles and aluminum foil covers. The 'ILP' dairy industry wastewater treatment process stages include bar screen, grease trap, equalization tank, flocculation-coagulation, primary clarifier, aeration tank/activated sludge, and secondary clarifier. The research aims to determine the performance of the dairy factory's WWTP (Wastewater Treatment Plant) in terms of TSS (Total Suspended Solids) and COD (Chemical Oxygen Demand) parameters. This field-scale research was carried out for approximately 5 weeks (35 days) at the wastewater treatment plant of the ILP company. Wastewater sampling is carried out at the inlet point, equalization tank, primary sedimentation, aeration tank, and outlet point of WWTP. Wastewater examination conducted in the company's internal laboratory, including temperature, pH, total suspended solids (TSS), and chemical oxygen demand (COD). The dairy factory WWTP (wastewater treatment plant) can generate TSS (total suspended solids) effluent of 22 mg/L and COD (chemical oxygen demand) of 26.8 mg/L to meet the applicable wastewater quality standards. The treatment efficiency of the dairy industry WWTP for TSS is 94.7% and COD is 98.1%.

Experimental investigation and Monte Carlo simulation of landfill leachate treatment using physicochemical method and a non-thermal plasma reactor

ABSTRACT Leachate treatment is one of the challenging subjects in the field of waste management. Leachate as a dumpling sites hazardous byproduct due to the high concentration of chemical oxygen demand (COD) and toxic compounds with dark colour is a potential pollutant of the environment, causing a lot of problems in the absence of treatment and direct discharge to the environment. In this study, the combinatory performance of sequential chemical flocculation and coagulation process and non-thermal plasma (NTP) technology on leachate from the Sarāvān city former controlled landfill, Iran, was investigated. The outcomes of Jar test illustrated that hydrated aluminium sulphate (PAC) was selected the best coagulant compared with hydrated aluminium sulphate (HAS) and ferric chloride (FC) to remove suspended solids and colour. The optimised parameters for 10% PAC pre-treatment were obtained 3 g lime and cationic 0.1 g polyelectrolyte per 1 litre of leachate. After pre-treatment by using jar test, NTP was used to remove turbidity, colour, COD and so forth. The sequential system-based all stages of pretreatment and NTP diminished the turbidity and colour removal to 98.6% and 99.2%, respectively. Furthermore, COD, BOD5, TSS, and TDS were also reduced. As a result, combination of pre-treatment and NTP technology are able to remove the landfill leachate effectively. Monte Carlo calculations exhibited that Al3+ and H2O2 had the most effects to decompose HA (Humic acid) compound in physicochemical pre-treatment and treatment stages.

Winter atmospheric deposition of trace elements in the Arkhangelsk region (NW Russia): Insights into environmental effects

Atmospheric precipitation is an important indicator of ecological status. Snow cover accumulates all atmospheric precipitation that occurs during the cold season and releases large amounts of matter into surface water streams during spring snowmelt. We measured chemical composition of suspended solids (>0.45 μm) and dissolved matter (<0.45 μm) of atmospheric precipitation sampled on a monthly basis in 4 stations of Arkhangelsk region in cold seasons of 2018–2021. The fluxes of insoluble particles increase consistently in the spring months. In winter, the largest fluxes of suspended solids from the atmosphere were observed in the urbanized areas (in Severodvinsk and Onega). Snow in Onega showed a significant enrichment in Mn as well as Rb, Sr, Cs, Ba and Pb, which is related to boiler house emissions. Severodvinsk snow is enriched in V, Ni in dissolved fraction and Al, V, Cu, Sr, Pb in suspended solids. The environmental risk assessment shows that Onega station is affected to high and extremely polluted conditions for Mn concentration and Severodvinsk station is affected to multi-element pollution from moderate to significant levels. Comparison with the composition of the river runoff of the Northern Dvina showed that the concentrations of Cu, Zn, Cd and Pb in the snow are equal to or even higher than the river concentrations, indicating that atmospheric precipitation accumulated during winter can significantly affect the geochemistry of river runoff with respect to these elements.