Biological Phosphate Research Articles

Comparative Analysis of Water Quality Index (WQI) from Selected Water Bodies in Different Regions of Southeast Nigeria

This study was carried out to compare the water quality index of selected water bodies in Okigwe, Imo State, Nigeria. Water samples were collected from two streams, Ihiku and Iyiechu (upstream and downstream) and the experimental research was used for this study. Several physico-chemical characteristics were analyzed in line with W.H.O, USEPA, S.O.N. The results obtained from the physico- chemical parameters ranged as follows: air shade temperature (23.3-25.0), pH (5.7-6.8), Electrical conductivity (15.5-20.4), Total hardness (33-40.5), Alkalinity (55.5-70.8), Biological Oxygen Demand (2.6-5.0), Dissolved Oxygen (6.5-8.0), Sulphate (1.8-5.7), phosphate (5.2-7.0) and silica (0.66-0.78). The result showed that there were variations in the concentration as a result of anthropogenic activities of man. The water quality index was also checked and compared to standards. The Pearson’s Correlation Moment was performed at 0.01% level. The result showed that values obtained were statistically significant. However, adequate treatment facilities that purify sewage prior to discharge or disposal should be adopted.

Thauera enriched granular activated carbon-assisted aerobic granular sludge performs enhanced biological nitrogen and phosphate removal via propionate utilization

Propionate constituting up to 25 % of volatile fatty acids in municipal wastewater, presents metabolic challenges for microorganisms. This study investigated the combined use of propionate along with granular activated carbon (GAC) for aerobic granular sludge (AGS) development and biological nutrient removal (BNR), particularly bio-P removal in granular reactors. GAC addition decreased granulation time and facilitated stable BNR pathways with propionate. AGS demonstrated robust settling properties (≥1 mm, 6 g/L MLSS, 40 mL/g SVI) with increased alginate-like exopolysaccharide (ALE) content up to 400 mgALE/gSS, indicating stable granule formation. Effective ammonium removal via simultaneous nitrification and denitrification was achieved. By day 90, phosphate removals reached 89 %, due to enrichment of polyphosphate accumulating organisms (PAOs) in GAC-containing AGS. The sludge fraction (>0.5 mm) comprised of granules and GAC-biofilms showed efficient phosphate removal through enhanced biological phosphate removal (EBPR). Enrichment of denitrifying PAO, Thauera sp., contributed to enhanced granulation, granular stability and nutrient removals.

Petroleum spills and assessment of heavy metals in water, sediment, soil from Afiesere River, Ughelli, Delta State, Nigeria

The study which was to determine the concentrations of heavy metals in water, sediment and soil of Afiesere river because of the anthropogenic activities of petroleum exploration and attendant spills in the area. Surface water, sediment, surface soil and sub-surface soil samples were collected from Afiesere River, Ughelli, Delta State. Some physiochemical parameters of water were analysed using standard methods and Hanna water quality checker. The concentrations of five heavy metals, namely; lead (Pb), cadmium (Cd), zinc (Zn), copper (Cu) and nickel (Ni) were determined in water, sediment, surface soil, and sub-surface soil using Flame Atomic Absorption Spectrophotometer (Flame-AAS). The results obtained show the mean values of pH, temperature, total dissolved solid, conductivity, dissolved oxygen, biological oxygen demand, phosphate, nitrate, and sulphate as follows: 6.87 ± 0.18, 27.40 ± 0.28oC, 4.00 ± 0.00 mg/L, 8.67 ± 0.25 µs/cm, 4.23 ± 0.08 mg/L, 0.65 ± 0.17 mg/L, 0.01 ± 0.00 mg/L, 0.01 ± 0.03 mg/L, and 2.17 ± 0.18 mg/L respectively. The heavy metals; Pb, Cd, Zn, Cu and Ni mean concentrations are as follows: in water, 0.06 ± 0.02, 0.02 ± 0.01, 0.46 ± 0.01, 0.03 ± 0.01 and 3.56 ± 0.07 mg/L; in sediment, 0.52 ± 0.03, 0.02 ± 0.00, 0.21 ± 0.02, 0.07 ± 0.01 and 0.26 ± 0.01 mg/kg; in surface soil, 0.50 ± 0.03, 0.02 ± 0.00, 0.07 ± 0.01, 0.03 ± 0.00 and 2.91 ± 0.03 mg/kg; in sub-surface soil, 0.55 ± 0.02, 0.02 ± 0.01, 0.26 ± 0.02, 0.06 ± 0.01 and 0.36 ± 0.08 mg/kg respectively. The results showed a significant difference at P<0.05. The results obtained in this study were within and above the set standard for water, sediment and soil by World Health Organization (WHO). The metals are toxic, can bio-accumulate and are potential carcinogens; therefore treatment of water is very important. Periodic medical examination of the inhabitants of the area must be a top priority.

Wastewater Treatment with Bacterial Representatives of the Thiothrix Morphotype.

Bacteria of the Thiothrix morphotype, comprising the genera Thiothrix, Thiolinea and Thiofilum, are frequently encountered in domestic and industrial wastewater treatment systems, but they are usually not clearly differentiated due to the marked similarity in their morphologies. Methods ranging from light microscopy, FISH and PCR to modern high-throughput sequencing are used to identify them. The development of these bacteria in wastewater treatment systems has both advantages and disadvantages. On the one hand, the explosive growth of these bacteria can lead to activated sludge bulking or clogging of the treatment system's membranes, with a consequent decrease in the water treatment efficiency. On the other hand, members of the Thiothrix morphotype can improve the quality of granular sludge and increase the water treatment efficiency. This may be due to their capacity for sulfide oxidation, denitrification combined with the oxidation of reduced sulfur compounds, enhanced biological phosphate removal and possibly denitrifying phosphate removal. The recently obtained pangenome of the genus Thiothrix allows the explanation, at the genomic level, of the experimental results of various studies. Moreover, this review summarizes the data on the factors affecting the proliferation of representatives of the Thiothrix morphotype.

Impact of feeding regimes on the performance of anaerobic sequencing batch membrane bioreactor treating wastewater from an urban drain

ABSTRACT This work evaluated an anaerobic sequencing batch membrane bioreactor (AnSBR-MBR) equipped with waste-based ceramic membranes for treating low-strength real drain wastewater. Two feeding regimes, viz. settled feed (Phase 1) and mixed feed (Phase 2) were compared. The biological performance (chemical oxygen demand (COD) and phosphate (PO43-) removal) and filtration performance (total suspended solids (TSS) removal and membrane fouling) were investigated. The reactor characteristics in terms of solids content, sludge settling behaviour, and extracellular polymeric substances (EPS) were also assessed. In Phase 1, the settled feed (with the absence of particulate organic matter) resulted in low volatile suspended solids (VSS; 0.23 ± 0.15 g/L), causing low COD removal (28.38 ± 8.14%). In the mixed feed regime in Phase 2, VSS increased (1.82 ± 0.60 g/L) due to the organic content in the particulate matter, which gave microorganisms additional food, resulting in increased COD removal (47.42 ± 2.81%); this phase was also characterised by lower membrane fouling because of the lower EPS content. Marginally higher TSS removal was obtained as well in Phase 2 (96.72 ± 3.26%) than in Phase 1 (90.48 ± 8.14%). This work demonstrates that AnSBR-MBR performance is superior with mixed drain wastewater containing suspended solids and thus pre-settling is not recommended.

Assessment of water quality for Al-Salibat marsh\\Southern Iraq

The objective of the current study is to assess if water is suitable for drinking, irrigation, and aquatic life. From April 2021 to January 2022, water samples were taken on a monthly basis from three locations in the Salibat marsh. To apply the Canadian index, fourteen variables were tracked, including (Water temperature (WT), pH, Turbidity (Tur), Electrical conductivity (EC), Total dissolved solids (TDS), Dissolved Oxygen (DO), Biological oxygen demand (BOD5), Total hardness (TH), Nitrate (NO3), Nitrite (NO2), Active Phosphate (PO4), Cadmium (Cd), Lead (Pb) and Zinc (Zn)). The results showed that the water temperature varied from (20.1 to 39) C°. pH values ranged between (7.1-9.5), Turbidity (9.8-54.78) NTU, total hardness that varied from (120 to 560) CaCO3mg/l. Electrical conductivity was between (2650-23220) μs/cm. Total dissolved solids ranged between (1014-9428) mg/l, dissolved oxygen and biological oxygen demand ranged between (5-9.1) (10-18) mg\\l respectively. Nitrate, nitrite and phosphate ranged between (0.14-59.10), (0.16-10.13), (0.04-5.65) μg\\l, Cadmium, Zinc and Lead (0-0.022)(0-0.50)(0-0.42) mg\\l. Results showed that the water quality was varied from marginal to good for irrigation but poor to marginal for aquatic life. It was also poor to marginal for drinking. Results showed that the water was suitable for irrigation, but not for drinking or aquatic life.

Assessing the Efficiency and Role of Duckweed (Lemna Minor) in the Removal of Pollutants from Wastewater Treatment Plant Secondary Clarifier Tanks: A Comprehensive Review

Aquatic plants, including duckweed (Lemna minor), are increasingly utilized in sewage and wastewater treat-ment to improve pollution parameters and organic matter removal. This study aimed to investigate the impacts and efficacy of duckweed in secondary clarifier tanks in a conventional biological treatment facility. The per-formance of four secondary clarifiers with and without duckweed was compared based on water quality efflu-ent and settling characteristics. As per the experiment results, the secondary clarifier tank with duckweed demonstrated higher removal efficiency for chemical oxygen demand (COD), biological oxygen demand (BOD5), ammonium, phosphate, total nitrogen (TN), and total phosphorus (TP) – of 70%, 75%, 72%, 82%, 67%, and 96%, respectively, compared to the tank without duckweed. The concentration of suspended solids in the effluent and sludge volume index (SVI) values were similar in both settings. The research findings suggest that duckweed can contribute to the treatment efficiency of conventional biological treatment plants, thus re-ducing the need for tertiary nutrient removal. Additionally, the cost-effectiveness of treatment with duckweed and its reuse as fertilizer and animal fodder make it a valuable resource. The optimal temperature for duck-weed growth is approx. +26°C, and it is influenced by sunlight and temperature more than nutrient concentra-tions.

Temporal Variation of Water Quality in Nilwala River, Southern Province, Sri Lanka

This study intended to investigate the temporal variation of water quality of the Nilwala river in the Matara district and to determine how the changes in rainfall affect to river water quality. Water samples were collected monthly from March 2019 to October 2019 (considering the second Inter monsoon season and first inter-monsoon season) at eight locations along the main river. Water quality parameters such as chemical oxygen demand (COD), biological oxygen demand (BOD), pH, electrical conductivity, temperature, alkalinity, hardness, chloride, nitrate and phosphate were analyzed using APHA 23rd edition of standard methods for the examination of water and wastewater. Experimental results were statistically analyzed by Two-way ANOVA using Minitab 17. The pH, EC, temperature, alkalinity and nitrate concentration showed statistically significant differences among the months (p<0.001) and those showed statistically significant differences with monthly rainfall (p< 0.001). There is a statistically significant relationship between rainfall and month (p<0.001). There is a statistically significant relationship between rainfall and sampling location (p<0.001). The highest rainfall was recorded from august to November (2nd inter-monsoon season) and secondly from March to May (1st inter-monsoon season) was recorded. Conductivity, pH and temperature were decreased from March to June. This may due to 1st inter monsoon rainfall. Conductivity was increased during august-november. Flooding can increase conductivity when it washes salts and minerals from the soil into the water. Nitrate concentration in the majority of the locations was increased during march-may. Total alkalinity, pH and nitrate were increased from august to November. The temperature of river water at all locations decreased from august- November. In conclusion, the pH, EC, temperature, alkalinity and nitrate concentration showed statistically significant differences among each month. It may due to variation of rainfall. Upper part of Nilwala River had a higher rainfall than lower basin.
 Keywords: Conductivity, Nilwala River, pH, temporal variation, Water quality

Baku mutu kualitas air muara sungai di kawasan Pura Petitenget dan upaya pengendaliannya

The main objective of this research is to analyze the quality standards for the quality of flowing water and river estuaries in the Petitenget Temple Area and efforts to control pollution or reduce the quality standards for flowing and river estuary water in the Petitenget Temple Area. The research was conducted from December 2018 to April 2019 in the river that flows into Petitenget Beach by taking four sampling points. The quality of water quality standards is measured using the water quality standards of Bali Governor Regulation No. 16 of 2016 concerning Environmental Quality Standards and Standard Criteria for Environmental Damage. The results of the research found that the quality of the water quality standards in the Petitenget Temple area had experienced pollution, namely the parameters of turbidity, chemical oxygen demand (COD), biological oxygen demand (BOD5), phosphate (PO4-P), total ammonia (NH3-N), fecal coliform, and total coliform. Efforts that can be made to overcome pollution in Loloan waters and river estuaries in Petitenget are the creation of Waste Management Regulations through the 4R (Reuse, Reduce, Recycle, Replace) pattern, limiting the use of chemical fertilizers and pesticides, creating waste storage and processing (septic tanks), and involving traditional villages (based on traditional villages) as well as environmental law enforcement.

Biogeochemical explanations for the world’s most phosphate-rich lake, an origin-of-life analog

Environmental phosphate concentrations are typically much lower (~10−6 M) than needed for prebiotic phosphorylation of nucleosides, critical for the origin of life. Here, we tested hypotheses explaining highly concentrated dissolved phosphate in carbonate-rich “soda” lakes by examining phosphorus and nitrogen cycling in Last Chance Lake and Goodenough Lake, Canada. We find a lack of geochemical phosphorus precipitation, that sedimentary calcium is in dolomite rather than apatite, and that N2-fixation rates, probably suppressed by high salinity, are too low to create significant biological phosphate demand. Thus, nitrogen-limitation of biological production and precipitation of calcium-rich carbonate instead of apatite combine to allow unimpeded evaporative phosphate buildup in Last Chance Lake to the highest known natural levels (37 mM) due to small biological and geochemical phosphorus sinks. Forming on basaltic rock, which was likely common on early Earth, evaporative soda lakes were consequently plausible origin-of-life settings with sufficient phosphate for prebiotic synthesis.

Multivariate analysis of water quality of "omi-omo" stream Ikole Ekiti, Nigeria.

The multivariate Principal Component Analysis (PCA) was used to assess the variations in the water quality of the "Omi Omo" Stream. This allowed for the identification of temporal and spatial variations in the water quality caused by contamination by analysing the similarities and differences between the sampling points. For three months, four sampling locations along the streamline provided data on the quality of the water. Temperature and other physicochemical parameters were used to analyse the samples. Turbidity, alkalinity, Electrical Conductivity (EC), hardness pH, Total Dissolved Solids (TDS), Dissolved Oxygen (DO), Biological oxygen demand (BOD), heavy metals (Cd, Cu, Pb, Fe, Mn), sulphate, phosphate, nitrate and chloride were also determined. For the months under study, PCA helped identify and extract the factors causing variations in water quality. The important factors influencing the variation in water quality for the three months of study were turbidity, TDS, alkalinity, electrical conductivity, nitrate, calcium, and chloride. The comparison of the stream’s physicochemical parameters with the W.H.O standards shows an acceptable correlation except for the turbidity and the EC which for some period were higher than the acceptable level of the W.H.O standard. The study's findings will assist pertinent authorities in determining how to improve the declining water quality caused by pollution from various human activities.

Spatial and temporal pattern of zooplankton assemblage in response to Limnological factors of river, Yamuna

Zooplankton plays a key role in maintaining aquatic ecosystem quality and is closely related with the community structure. During the present investigation, the zooplankton samples were collected from the three different sampling stations of River Yamuna for a period of one year from April 2012 to March 2013. The physico-chemical parameters of water such as temperature, transparency, velocity, turbidity, conductivity, pH, total alkalinity, total hardness, calcium, magnesium, dissolved oxygen, biological oxygen demand, phosphate and nitrate. The temperature ranged from 17.0±2.59 oC to 18.58±2.90oC and pH showed slightly alkaline nature. Sampling station, I registered a maximum dissolved oxygen concentration of 11.41±0.775 mg/l and minimum nutrient concentration. A total of 29 genera of zooplankton belonged to four different taxonomic groups were identified. Among these 10 genera belonged to protozoa, 11 genera belonged to rotifera, 6 genera belonged to copepod and 2 genera belonged to ostracoda. The zooplankton density was highest at sampling site I with maximum number of individuals belonging to all the four group. Rotifera formed the dominant group followed protozoa, copepoda and ostracoda. Daphnia, Asplanchna and Paramecium was reported with highest number of individuals during the entire study period. The total zooplanktonic richness generally indicated favorable environmental conditions and these were characterized by tolerant of widely fluctuating environmental conditions. Pearson correlation coefficient and Shannon- Weiner diversity index (H’) was calculated.

Impact of Physico-Chemical and Biological Parameters on Zooplankton Composition and Abundance in Freshwater Lake of Mulukanoor Karimnagar District, Telangana

The plankton constitutes the basic food sources of any aquatic ecosystem, which Supports fish and other aquatic animals. Zooplankton diversity is one of the most important ecological parameters in water quality assessment. Zooplankton is good indicator of the changes in water quality because they are strongly affected by environmental conditions and respond quickly to changes in water quality. In the present paper, Zooplankton diversity in relation to physico-chemical parameters of the Mulukanoor Lake located in Krimnagar District, Telangana state.The study was carried out for a period of one year from June 2015 to May 2016 to evaluate the relationship and influence between different water quality parameters and the abundance of zooplankton population. The physico-chemical parameters includes Temperature, Electrical Conductivity, Total Dissolved Solids, Water Transparency, PH, Dissolved Oxygen.Free Co2, Total Alkalinity, Total Hardness, Chloride, Biological Oxygen Demand, Phosphate, Nitrate and Ammonia were analyzed. All the values of these parameters were found within the prescribed standard limits. Therefore this lake has rich number of species biodiversity of aquatic animals. Four different groups of zooplankton were identified in this study which includes Rotifera, Cladocera, Copepoda and Ostracoda. Zooplankton diversity and abundance refers to variety within in the community. Numerically rotifers were dominant group throughout the study period. The season wise zooplankton analysis showed a maximum average abundance of species in Post-Monsoon season, minimum abundance in monsoon season due to the different environmental and inflow characteristics of the water body. The composition of zooplankton rotifers was dominant Rotifera(56%) followed by cladocera (23%), copepod (13%) and ostracoda (8%).Therefore it can be now concluded that this lake is highly potential to take up commercial fisheries.

New model of long-term changes in spatiotemporal patterns of water quality across Shatt-Al-Arab River by applying GIS technique, from 1976 to 2020

PurposeUsing a combination of the geographical information system (GIS) and the Canadian water quality index (WQI), the current study sought to provide a long-term general assessment of the water quality of the Shatt Al-Arab River (SAAR), focusing on its suitability for living organisms. Likewise, SPSS statistics was used to develop a nonlinear WQI regression model for the study area.Design/methodology/approachThe study required four decades of data collection on some environmental characteristics of river water. After that, calculate the WQI and conduct the spatial analysis. Eight variables in total, including water temperature, dissolved oxygen, potential hydrogen ions, electrical conductivity (EC), biological oxygen demand, turbidity, nitrate and phosphate, were chosen to calculate the WQI.FindingsThroughout the study periods, the WQI values varied from 55.2 to 79.83, falling into the categories of four (marginal) and three (fair), with the sixth period (2007–2008) showing the most decline. The present research demonstrated that the high concentration of phosphates, the high EC values, and minor changes in the other environmental factors are the major causes of the decline in water quality. The variations in ecological variables' overlap are a senior contributor to changes in water quality in general. Notably, using GIS in conjunction with the WQI has shown to be very effective in reducing the time and effort spent on investigating water quality while obtaining precise findings and information at the lowest possible expense. Calibration and validation of the developed model showed that this model had a perfect estimate of the WQI value. Due to its flexibility and impartiality, this study recommends using the proposed model to estimate and predict the WQI in the study area.Originality/valueEven though the water quality of the SAAR has been the subject of numerous studies, this is the only long-term investigation that has been done to evaluate and predict its water quality.

Effectiveness of Chlorella sp. in phytoremediation of different wastewater in North Aceh

Chlorella sp. is microalgae species used to treat wastewater and can grow and develop well inside contaminated environments by interweaving symbiosis with bacterial decomposers. This study purposed to evaluate the effectiveness of Chlorella sp. in the phytoremediation of different wastewater from North Aceh. This research used the experimental laboratory method with an experimental design Non-Factorial Completely Randomized Design. The treatment factor was different wastewater obtained from North Aceh consisting of A: domestic wastewater, B: tofu wastewater, and C: slaughterhouse wastewater repeated three times. The observed parameters were water quality parameters (temperature, pH, dissolved oxygen, biological oxygen demand, nitrate, and phosphate concentration, decrement of organic materials, and microalgae growth. The result showed that Chlorella sp. could remediate the wastewater by decreasing the organic materials in the wastewater. The temperature, pH, and dissolved oxygen in wastewater were optimal for Chlorella’s life. Implementation of Chlorella sp. gave a significant effect (p<0.05) on the efficiency of organic materials decrement in wastewater, namely BOD 64,6%-65%, nitrate 76,8%-91,2%, and phosphate 72,7%-94,6%. Furthermore, the suitable wastewater for Chlorella sp. growth with its highest peak value (p<0,05) was the slaughterhouse wastewater. The recommended wastewater was slaughterhouse remediated by Chlorella sp. to be used as cultivation media of fish.

Aerobic granular sludge phosphate removal using glucose

Enhanced biological phosphate removal and aerobic sludge granulation are commonly studied with fatty acids as substrate. Fermentative substrates such as glucose have received limited attention. In this work, glucose conversion by aerobic granular sludge and its impact on phosphate removal was studied. Long-term stable phosphate removal and successful granulation were achieved. Glucose was rapidly taken up (273 mg/gVSS/h) at the start of the anaerobic phase, while phosphate was released during the full anaerobic phase. Some lactate was produced during glucose consumption, which was anaerobically consumed once glucose was depleted. The phosphate release appeared to be directly proportional to the uptake of lactate. The ratio of phosphorus released to glucose carbon taken up over the full anaerobic phase was 0.25 Pmol/Cmol. Along with glucose and lactate uptake in the anaerobic phase, poly‑hydroxy-alkanoates and glycogen storage were observed. There was a linear correlation between glucose consumption and lactate formation. While lactate accounted for approximately 89 % of the observed products in the bulk liquid, minor quantities of formate (5 %), propionate (4 %), and acetate (3 %) were also detected (mass fraction). Formate was not consumed anaerobically. Quantitative fluorescence in-situ hybridization (qFISH) revealed that polyphosphate accumulating organisms (PAO) accounted for 61 ± 15 % of the total biovolume. Metagenome evaluation of the biomass indicated a high abundance of Micropruina and Ca. Accumulibacter in the system, which was in accordance with the microscopic observations and the protein mass fraction from metaproteome analysis. Anaerobic conversions were evaluated based on theoretical ATP balances to provide the substrate distribution amongst the dominant genera. This research shows that aerobic granular sludge technology can be applied to glucose-containing effluents and that glucose is a suitable substrate for achieving phosphate removal. The results also show that for fermentable substrates a microbial community consisting of fermentative organisms and PAO develop.

Assessment of the potentials of <i>Azotobacter</i> spp. as bioinoculants on the growth of potted maize plants

The use of chemical fertilizers in crop production has detrimental effects such as soil acidity and eutrophication. There is need for environmentally friendly approach in improving soil nutrients and agricultural productivity. This study aimed at the isolation of Azotobacter spp from the rhizosphere of crops and the use of these isolates as biofertilizer for the growth of potted maize plants under 5 treatments. These treatments were maize plant only (control), plant with once application of NPK fertilizer, plants with once, weekly and fortnights application of Azotobacter spp. as bio-inoculants. The counts of Azotobacter obtained from the rhizosphere of the crops ranged from 4.0 × 104 – 1.0 × 106 CFU/g. The three high ranking in-vitro biological nitrogen fixing and phosphate solubilization isolates were identified A. chroococcum, A. vinelandii and A. beijerinckii. At the 7th weeks of growth, 83.3 and 100% of the plants that received different levels of bio-inoculants had the perimeter of their girths greater than and significantly different from the controls when cultivated in 8.1 and 12.0 litre pots respectively. At least 91.7% of the plants that received bio-inoculants had higher heights than the controls. It is concluded that the application of Azotobacter bio-inoculants enhanced the growth of maize plants compared to the contro

Biological calcium phosphate nanorods for piezocatalytical extraction of U(VI) from water

Biological calcium phosphate nanorods for piezocatalytical extraction of U(VI) from water

Denitrifying phosphorus removal (DPR) performance and metabolic mechanisms of Tetrasphaera at long-term nitrite exposure

Tetrasphaera has been identified as the main polyphosphate-accumulating organism (PAOs) in enhanced biological phosphate removal (EBPR), but the ability of Tetrasphaera to use nitrite as electron acceptor for denitrifying phosphorus removal (DPR) is still unclear. This study investigated the DPR performance and mechanism, microbial structures, and FNA inhibition of Tetrasphaera-dominated culture in the long-term acclimatization at different nitrite concentrations (10, 20, 40 and 50 mgN/L). The results showed that the most optimal influent nitrite concentration was 20 mgN/L (C/N = 6), and the removal efficiency of nitrite and phosphorus reached above 90 % and 95 %, respectively. Fluorescence In Situ Hybridization-Flow Cytometry (FISH-FCM) showed that the population abundance of Tetrasphaera was 80.95 %, in which Tet2-892 clade was the most abundant and mainly responsible for DPR with nitrite as electron acceptor. When the nitrite concentration reached 50 mgN/L (FNA = 12.80 µgHNO2-N/L, pH = 7.0 ± 0.1), electron supply deficiency and FNA inhibition resulted in only 43.0 % and 68.4 % of nitrite and phosphorus removal efficiency, respectively. The intracellular amino acid and glycogen metabolism were inhibited by FNA under this condition. A significant accumulation of N2O was observed, resulting from a combination of the insufficient electron supply, absence of nos-Z gene, and long-term FNA inhibition. DPR dominated by Tetrasphaera with appropriate nitrite as electron acceptor provides a new way to achieve nitrogen and phosphorus simultaneous removal. In addition, this study found that Tet2-892 clade of Tetrasphaera was more tolerant to FNA compared to Accumulibacter and GAOs, which provides a strategy for inhibiting GAOs activity to maintain the stability of the EBPR system.

Assessment of water quality of Tigris River by using WQ index in Salah Al-Din province

The management of water resources depends on the evaluation of water quality. In this research, Water Quality Index (WQI) was used to evaluate Tigris River water quality for drinking water purposes and assess significant factors that affect water quality. The physiochemical parameters measurements of water samples taken from four sites along the river within Salah Al-Din province were collected from October 2022 to May 2023, including water temperature, turbidity, Electrical Conductivity (EC), Total dissolved Solids (TDS), pH, Dissolved Oxygen (DO), Biological oxygen demand (BOD5), Total harness, Calcium, Magnesium, Total Alkaline, Chloride, Sodium, Potassium, Sulfate, Nitrite, and Phosphate. The results of WQI values ranged from 71.28 to 90.78, the water was considered poor to very poor in the study sites, due to the water getting polluted to some extent, so the value of WQI decreases. This indicated the Tigris River in the study area was unsuitable for drinking uses.