Chemical Oxygen Demand Concentration Research Articles

Industrial indigo dyeing wastewater purification: Effective COD removal with peroxi-AC electrocoagulation system

Direct current (DC) electrocoagulation has obvious decolorization effect on indigo dyeing wastewater produced in actual production, while the removal rate of chemical oxygen demand (COD) was less than 40%, accompanied by serious electrode corrosion and high energy consumption. In order to enhance the COD removal rate, reduce the electrode loss and power consumption, a peroxi-alternating current (AC) electrocoagulation (EC) system was constructed. With COD as the main evaluation index, the effects of power type, electrode combination and process parameters on COD removal rate and decolorization rate were focused on and explored, as well as revealing the degradation mechanism of COD. The results showed that AC electrocoagulation enhanced the floc adsorption capacity by improving the floc structure, and the COD removal rate after treatment was 51.19%. The coupled system of peroxi-AC electrocoagulation further removed sulfite and residual dyes in the wastewater, and the COD removal and decolorization rate of the treated wastewater reached 78.09% and 98.47%, respectively. In addition, the specific energy consumption analysis of COD removal showed that the coupled system was far less energetic than the DC electrocoagulation process, with only 30% of its energy consumption. The uniform corrosion of the electrode under the action of AC weakened the passivation, which reduced the electrode loss and power consumption by 22.73% and 43.75%, respectively. Results from the present work indicated that the peroxi-AC EC system could be an effective method for reducing the concentration of COD in indigo dyeing wastewater.

Enhancement effect of biochar addition on anaerobic co-digestion of pig manure and corn straw under biogas slurry circulation

Based on the semi-continuous anaerobic co-digestion (AcoD) reactor, the effects of biochar addition on the internal environmental changes and gas production characteristics were studied under the condition of biogas slurry recirculation. The results showed that the addition of biochar enhanced the degradation and metabolic pathways of acetate and propionate, thereby reducing the concentrations of volatile fatty acids (VFAs), total ammonia and chemical oxygen demand by 55 %, 41 % and 61 %, respectively. The buffer system formed by the combination of NH4+ and VFAs of C2-C5 was also enhanced, thereby improving the stability of the system. The addition of biochar effectively increased the relative abundance of Bacteroidetes, Chloroflexi, Spirochaetota and Synergistota, and enhanced three methanogenic metabolic pathways. This study provides scientific support for the application of biochar to solve the system inhibition in mixed substrate semi-continuous AcoD process and provides technical support for the stable operation of biogas project.

Alga-based dairy wastewater treatment scheme: Candidates screening, process advancement, and economic analysis

The common means of wastewater pre-treatment is impractical in large-scale wastewater treatment plants (WWTP). There is still a lack of suitable microalgae to treat raw dairy wastewater (DWW) with high organic matter concentration. For screening more diverse microalgae to treat raw DWW, the growth characteristics and metabolite production of ten algal strains cultured in undiluted DWW were studied in this paper, among which three were able to tolerate excessive chemical oxygen demand (COD) concentration and yielded high biomass concentration. Under the condition of 25 ± 1 °C and 55 μmol/m2/s, the most suitable strain were Scenedesmus SDEC-13, Chlorella pyrenoidosa SDEC-35, and Chlorella vulgaris SDEC-34, all of which had biomass concentrations above 1.2 g/L and protein contents above 45%. Based on the feasibility of cultivating microalgae with raw DWW, an alternative alga-based WWTP strategy was provided for the first time. The most important modification was the construction of the photobioreactor (PBR) to replace hydrolytic upflow sludge bed (HUSB) reactor and remove anaerobic-aerobic (AO) pond. The dairy WWTP with a PBR unit (1.68 × 104 m3) will yield a biomass production of 1.44 × 106 kg/year while capturing 2.59 × 106 kg CO2/year. Through carbon comparison and economic analysis, we believe that the use of microalgal PBRs for the treatment of wastewater from dairy plants presents a cost-effective and environmentally friendly alternative for the future. And future research should focus on pilot scale photobioreactor in the natural environment and large-scale treatment of dairy wastewater.

Monitoring the Variability of the Pollutant Level in Urban Water Front during Dry and Wet Seasons

The variability of the physicochemical properties of River water during the dry season (DS) and rainy season (RS) were carried out using Bonny Water Front Creek (BWFC) as case study. The levels of physicochemical properties including: pH, temperature (T), electrical conductivity (EC), turbidity, salinity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), total dissolved solids (TDS), salinity, polycyclic aromatic hydrocarbon (PAH), iron (Fe), lead (Pb), chromium (Cr) and mercury (Hg), vanadium (V), magnesium (Mg), cadmium (Cd), and nickel (Ni) were analyzed. Water samples were collected along the coastal line in the direction of flow of the water at intervals of 10m from the pollution source up to 100 meters on the water surface with the aid of boat moving from the upstream to downstream in the direction of water flow. The experimental results showed the average concentration of pH (7.52), EC (22355.00µs/cm), T(30.14OC), turbidity (11.64NTU), Salinity (18.91mg/l), B0D(18.07mg/l), COD (55.10mg/l), DO (4.29mg/l), TDS (16.26mg/l), The pH values were within acceptable range, EC, turbidity, TDS, and salinity were above WHO acceptable limit of 1000s/cm, 5NTU, 24-28, N/S, respectively. Also, BOD and COD concentration equally indicated that the Creeks were polluted. Similarly, the concentrations of some heavy metals in the creeks during both seasons were higher than limits given by World Health Organization for river water. Therefore, suggesting for continuous assessment and remedial techniques or treatment process must be applied to ascertain pollutant levels in the creeks to inhabit aquatic life.

Treatment of Landfill Leachate by Short-Rotation Willow Coppice Plantations in a Large-Scale Experiment in Eastern Canada

The treatment of leachate by vegetative filters composed of short-rotation willow coppice (SRWC) has been shown to be a cost-effective alternative to conventional and costly methods. However, few studies have considered the treatment capability of willow filters at a scale large enough to meet the industrial requirements of private landfill owners in North America. We report here on a field trial (0.5 ha) in which a willow plantation was irrigated with groundwater (D0) or aged leachate at two different loadings (D1 and D2, which was twice that of D1). Additionally, half of the D2-irrigated plots were amended with phosphorus (D2P). The system, which operated for 131 days, was highly efficient, causing the chemical oxygen demand concentration to drop significantly with the total removal of ammonia (seasonal average removal by a concentration of 99-100%). D2P efficacy was higher than that of D2, indicating that P increased the performance of the system. It also increased the willow biomass 2.5-fold compared to water irrigation. Leaf tissue analysis revealed significant differences in the concentrations of total nitrogen, boron, and zinc, according to the treatment applied, suggesting that the absorption capacity of willows was modified with leachate irrigation. These results indicate that the willow plantation can be effective for the treatment of landfill leachate in respect of environmental requirements.

Comparative Study on Enhanced Photocatalytic Activity of Visible Light-Active Nanostructures for Degradation of Oxytetracycline and COD Removal of Licorice Extraction Plant Wastewater

This study evaluates the effects of carbon, nitrogen, and sulfur dopants on the photocatalytic activity of TiO2 for degradation of oxytetracycline (OTC) and chemical oxygen demand (COD) removal from licorice extraction plant wastewater (LEPW). Three novel visible-light-responsive nanostructures, including L-Histidine-TiO2, L-Methionine-TiO2 and L-Asparagine-TiO2, were successfully synthesized. The results showed that the modification of TiO2 with these three amino acids made the catalyst active in the visible light region and reduced the recombination rate of e−/h+ pairs according to PL analysis. The photodegradation efficiency of L-Histidine (2 wt.%)-TiO2 was 100% and 94% for OTC and COD, respectively. It showed the highest photocatalytic activity under illumination, compared to L-Methionine (1.5 wt.%)-TiO2 and L-Asparagine (2 wt.%)-TiO2. Synthesized composites were characterized with SEM, XRD, FTIR, DRS, and PL analyses. The biological oxygen demand to COD (BOD5/COD) ratio for treated LEPW was determined to be 0.5–0.6, confirming the enhanced biodegradability of the treated effluent. The effect of the independent variables, namely, initial concentration of OTC and COD, catalyst dosage, irradiation time, pH of solution, and light intensity, on the photocatalytic process was evaluated by Response Surface Methodology (RSM), and the optimum value of each independent parameter for maximum degradation of OTC and COD by L-Histidine (2 wt.%)-TiO2 was determined. The radical trapping experiment was performed with various scavengers in order to propose a photocatalytic mechanism, showing that hydroxyl radicals were the main active species. L-Histidine (2 wt.%)-TiO2 showed a stable and reusable structure even after four cycles of COD removal under the following optimal conditions of [COD]: 300 mg/L, [catalyst]: 1 g/L, light intensity: 25 W/cm2 at pH = 4 after 180 min irradiation.

Optimization of a compact on-site stormwater runoff treatment system: Process performance and reactor design

Stormwater runoff has become a major anthropogenic urban pollution source that threatens water quality. In this study, coagulation-sedimentation, and ammonium ion exchange and regeneration (AIR) modules were coupled as a CAIR system to efficiently treat stormwater runoff. In the coagulation module, 99.3%, 91.7%, and 97.0% of turbidity, total phosphorus, and chemical oxygen demand could be removed at an optimized poly-aluminum ferric chloride dosage of 30 mg/L, and the continuous experiment confirmed that the full load mode was more suitable for its rapid start-up. In the AIR module, dynamic ammonium removal indicated that the breakthrough time decreased with the rising initial concentration and superficial velocity. The Modified Dose Response (MDR) model described the ammonium exchange behavior better than the Thomas and the Bohart-Adams models. Then, a design flow of the ion exchange reactor was constructed by correlating constants in the MDR model with engineering parameters, and the ion exchange reactor was designed for continuous operation of the CAIR system. The average concentrations of chemical oxygen demand, total phosphorus, ammonium nitrogen, and total nitrogen in the effluent of the CAIR system were 7.22 ± 2.26, 0.17 ± 0.05, 1.49 ± 0.01, and 1.62 ± 0.02 mg/L, respectively. The almost unchanged exchange capacity and physicochemical properties after the multicycle operation confirmed the durability of zeolite for ion exchange. Techno-economic analysis suggested that the CAIR system is practically promising for stormwater management with efficient pollutants removal, small footprint, and acceptable operating cost.

Dual-chamber microbial fuel cells as biosensors for the toxicity detection of benzene, phenol, chromium, and copper in wastewater: Applicability investigation, effect of various catholyte solutions, and life cycle assessment

Microbial fuel cells (MFCs) were investigated as biosensors for the toxicity detection of benzene, phenol, chromium, and copper in wastewater as they can instantaneously indicate the presence of these contaminants. In this study, two rectangular MFCs, each composed of anodic and cathodic chambers separated by a proton exchange membrane, were operated in parallel. The anode comprised plain carbon cloth, and the cathode comprised plain carbon cloth covered by 0.5 mg/cm2 20% Pt. The anode chamber was filled with synthetic wastewater containing the designated chemical oxygen demand (COD) concentration, while the cathode chamber was filled with ferricyanide (MFC-F) or aerated tap water (MFC-T). The external resistances varied from 100 − 10,000 Ω, and organic load was assessed at COD values of 500, 750, and 1000 mg/L at a pH of 7. Toxic injections were performed at concentrations of 1, 5, 20, and 100 mg/L. Scanning electron microscope images revealed the formation of biofilm after the start-up period. The results indicate that the contaminants investigated caused an inhibitory effect when present at high concentrations. The inhibition ratios of benzene, phenol, chromium, and copper reached 2.9%, 5.1%, 41.8%, and 13.3%, respectively, for MFC-F. For MFC-T, the inhibition ratios of benzene, phenol, chromium, and copper were 14.3%, 10%, 10%, and 4.7%, respectively. MFC-T was more sensitive to the toxicity of organic compounds, while MFC-F was found to be more sensitive to heavy metal toxicity. A life cycle assessment was also conducted to determine the environmental impacts associated with the two biosensors.

Water quality variation of a typical urban landscape river replenished with reclaimed water

Replenishing landscape water with reclaimed water has been an effective way to alleviate urban water shortage. In order to investigate the variation of water quality along the pipeline and flow direction in a typical urban landscape river replenished with reclaimed water, relevant water quality indexes were consecutively monitored for 8 months. Concentrations of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) all showed a downward trend along the flow direction in reclaimed water effluent pipeline. However, values of turbidity, COD, and chlorophyll a (Chla) were decreased significantly, while concentrations of TN and TP were increased in the mixed area of reclaimed water and river. Furthermore, along Licun River, an upward trend of COD and ammonia-nitrogen (NH4+-N) was observed in summer, while in other seasons, a falling first and then rising trend of COD concentration appeared. The concentration of NH4+-N randomly fluctuated between 0.08 ​mg/L to 2.05 ​mg/L among all seasons, and TN and nitrate-nitrogen (NO3−-N) were below 15 ​mg/L with a downward first and then upward trend in each season. The concentration of TP showed a slightly upward trend (ranging from 0.08 ​mg/L to 0.57 ​mg/L) and Chla was at a relatively low level (0 – 46.32 ​μg/L). The correlation analysis revealed that light intensity, nitrogen and phosphorus were the influential factors of algae growth in river. In addition, the biomass of emergent plants and submerged plants was increased after replenishing with reclaimed water, playing a vital role in the remediation of urban landscape river.

Chemical coagulation and biological techniques for wastewater treatment

Abstract This paper reports the effectiveness of chemical coagulation and biological techniques for the treatment of wastewater from industrial and agricultural operations. Agricultural husbandry has been reported to produce wastewater that has high content of chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity as well as organic and inorganic pollutants. A comparison on the use of organic and inorganic based coagulants as well as the optimum conditions required for high percentage removal efficiency of pollutants from wastewater has been reviewed. At optimum experimental condition, ferric chloride coagulants were reported to yield 98, 95, 93 and 50 % removal of color, turbidity, iron and manganese. Moreover, chemical coagulation, electrocoagulation and biological methods have been reported to display a close range in their capacities for removing pollutants from wastewater. However, biological method was observed to be highly effective in the removal of pollutants from wastewater but requires more time and produces lesser volume of sludge, when compared to chemical method in the treatment of wastewater.

A COD measurement method with turbidity compensation based on a variable radial basis function neural network.

In recent years, ultraviolet-visible spectrometry has been widely used to measure sewage's chemical oxygen demand (COD). However, most methods that use UV-vis spectroscopy for COD measurement have not eliminated the influence of turbidity. Therefore, this article proposes a new COD measurement method using UV-vis spectroscopy. This method includes a new turbidity compensation algorithm and an algorithm for COD measurement using a variable radial basis function (VRBF) neural network. Our turbidity compensation algorithm first utilizes principal component analysis (PCA) to extract the characteristic wavelengths of the spectrum. Then, turbidity is used to fit the absorbance difference caused by turbidity at the characteristic wavelength, and a turbidity compensation model is obtained. The turbidity compensation model is used to remove the influence of turbidity from the absorbance spectrum, thereby compensating for its effect on the COD measurement. Secondly, the VRBF neural network model is used to measure the COD concentration. The results show that, compared with the traditional partial least squares regression model, the R2 coefficient of determination increases from 0.27 to 0.88, and the root-mean-square deviation decreases from 5.56 to 1.69. Compared with the improved bagging algorithm and MLP algorithm, this method can measure COD concentration from absorption spectra faster, more directly, and more accurately.

Design and Performance Evaluation of a Low-Cost Domestic Level Filter to Treat Kitchen Wastewater

The aspects of water security mainly govern by the availability and the quality of the water. As foreseen, use of portable fresh water for landscape irrigation can be a problem in the future. This research study was carried out with objectives of characterizing the raw kitchen wastewater (KWW), designing a domestic level filter for treating KWW and evaluating the removal efficiency of newly designed filter for reuse purpose. Four combinations of treatment systems were used namely in an order, sand and gravel layer, sand and bricks, sand and bricks with a coco peat layer and sand, bricks, coco peat and activated charcoal units for filtering. Raw kitchen wastewater samples were collected three times per day and made a composite sample by mixing equal proportion of each. Water quality parameters were measured before and after treatment of the KWW and compared with the Central Environmental Authority, Sri Lanka (CEA) standards. The average pH, Chemical Oxygen Demand (COD) and oil content in raw KWW was significantly higher than CEA standards. Based on results, raw KWW cannot be reuse for irrigation and it requires adequate treatment prior irrigation. The quality of filtrate from treatment system four resulted with the mean values of pH, electrical conductivity, temperature, total dissolved solids, COD and oil content and respectively quantitative figures were 7.2 ,0.65 mS cm-1, 29.5°C, 230.1 mg L-1, 365 mg L-1 and 2.8 g L-1 .The combination of sand, bricks, coco peat and activated charcoal filter filtrated effluent was within the CEA standards, which can be reuse for irrigation.

Determination of biokinetic coefficients of an aerobic system for potato starch removal

This study presents an aerobic laboratory scale-reactor completely mixed performance for starch wastewater treatment. The reactor was operated for 119 days divided into 5 operational phases which included the start-up and the variation of cell-residence time. In order to determine the biokinetic coefficients for starch removal, the cell-residence time was varied between 20 to 4 days, and the system operation was set hydraulic retention time of 24 hours with a completely mixed reactor setup. The chemical oxygen demand concentration was 1000mg/L in the inflow of the reactor and dissolved oxygen remained above 2mg/L. In this experimentation time, the parameters such as pH, chemical oxygen demand (in the influent and effluent), dissolved oxygen and Mixed liquor suspended solids were monitored. The calculation of biokinetic constants was done by an approximate method, using the graphical Lineweaver-Burk method. The biokinetic coefficients determined were for Maximum substrate removal rate , Half saturation rate constant or affinity constant ( sludge yield coefficient (Y), and Microbial decay or indigenous respiration rate . The results showed that Y, , and ( were in the range of 0,3- 0,7 mgSSV/mgBOD5, 2- 8 Day1 and 40-120 mg/L (COD- BOD5), respectively. Values of the coefficients were within the range of those reported for conventional activated sludge processes.

Microplastic Abundance From Pig Farm Effluent and Surface Water In Sungai Tuang, Melaka, Malaysia

Livestock is one of the country’s important economic resources, nevertheless, an unsystematic livestock farm management system contributes to microplastic pollution. Microplastics (MPs) pollutant hurts the environment and human life, limited studies have been done in Malaysia’s freshwater ecosystems. Therefore, this research was to determine the abundance of MPs in surface water and sediments from the nearby river and the last catchment pond of pig farm effluent in Paya Mengkuang and Sungai Tuang, Melaka. The concentration of MPs was compared with six water quality parameters (pH, biochemical oxygen demand (BOD), suspended solids (SS), dissolved oxygen (DO), total ammoniacal nitrogen (NH3-N), and chemical oxygen demand (COD). This study found that the average concentration of MPs was 487.38 particles/L and 50.96 particles/g for water and sediment samples consequently. This study showed a significant correlation between COD concentration and microplastic count in sediment samples. The source of microplastics in rivers is associated with anthropogenic activities such as unsystematic garbage disposal and poultry manure. The prevalence of microplastics in the environment of MPs could threaten the safety of resource utilization as MPs enter the food chain in aquatic ecology and pose a severe threat to aquatic organisms directly and subsequently to humans. Our study provides essential data on microplastic pollution in river estuaries and livestock farm areas.

Application of iron–carbon microbial galvanic activated sludge combined with MBR process in the treatment of wastewater from comprehensive railway station

The application of iron–carbon microbial cell activated sludge (ICMC-AS) was carried out in a membrane bioreactor (MBR) processor to treat wastewater from an integrated railway station. Results showed that the chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) removal efficiencies of the original MBR processor increased from 80%, 30%, and 10% to 92%, 93.5%, and 92%, respectively. Further research showed that the combined sewage treatment system also had a strong impact resistance ability. The combined sewage treatment system ran stably when the COD, TN, and TP concentrations changed greatly. The in-depth analysis of the reaction process and reaction rate of the combined sewage treatment system revealed that the combined system is dominated by COD removal with high nitrogen removal efficiency. The removal rate constants of various pollutants were in the order: KCOD (0.647 ± 0.017) > KNO3−−N (0.416 ± 0.044) > KNH4+−N (0.275 ± 0.014) > KTN (0.258 ± 0.083). Calculations of the energy saving and carbon emission reduction of the combined system showed that the system’s annual carbon emission reduction could reach more than 388,203.55 kg CO2e, which remarkably improves the carbon emission reduction effect and obtains a good green effect. The results indicate that adding ICMC-AS to the MBR processor for combined wastewater treatment can substantially improve the efficiency of wastewater treatment and obtain better energy-saving and emission-reducing effects. This combined application provides an effective way for the transformation and upgrading of small- and medium-scale water treatment systems.

A novel coupled microbial fuel cell operation for organic and nitrogen removal with simultaneous energy recovery from wastewater

The inherent disadvantage of MFC in wastewater treatment is low energy recovery and is even lower when dealing with nitrogen. This study investigated a novel coupled MFC, where each MFC is designed or configured to accomplish different tasks. The 1st MFC was responsible for dominating the electricity generation from oxidation of organics and the 2nd MFC for nitrogen removal with an adequate minimum amount of carbon. At the 1st MFC, 88.3–98.7 % of organic matter was removed with an average power density of 3432–3847 mW m−3 depending on the initial chemical oxygen demand (COD) concentration. Ammonium was completely oxidized to nitrite and nitrate in the cathode chamber of the 1st MFC. These were then reduced in both chambers of the 2nd MFC helping to achieve a total nitrogen removal of 56.5–79.8 %. The high ratio of autotrophic denitrification demonstrated that bioelectrochemical denitrification is the main pathway in the cathode chamber of 2nd MFC when the remaining organic carbon is minimal. The cathodic nitrification and anodic heterotrophic denitrification processes contributed to pH stability in these chambers. These findings indicated a suitable operating method for a coupled MFC that can efficiently remove nitrogen and maximize the energy recovery from organic matter in wastewater.

Irrigation suitability, health risk assessment and source apportionment of heavy metals in surface water used for irrigation near marble industry in Malakand, Pakistan.

Water is a vital, finite resource whose quantity and quality are deteriorating as the world population increases. The current study aims to investigate the concentration of heavy metals (HM) in surface water for irrigation purposes with associated human health risks and pollution sources near the marble industry in Malakand, Pakistan. Twenty-seven water samples were randomly collected and analyzed for HM concentration by inductively coupled plasma‒optical emission spectrometry (ICP‒OES). pH, electrical conductivity (EC), total dissolved solids (TDS), biological oxygen demand (BOD), and chemical oxygen demand (COD) were measured using standard methods of American Public Health Association (APHA). Irrigation suitability was assessed using specific water quality parameters. The associated health risks from ingestion and dermal exposure to heavy metals were calculated by USEPA health risk indices. Pollution sources and spatial distribution mapping were studied using compositional data analysis (CoDa) and the application of a geographic information system (GIS) to understand the changing behavior of heavy metals in surface waters. The concentrations of BOD (89%), COD (89%), Al (89%), Ca (89%), Cr (56%), Cu (78%), Fe (56%), K (34%) Mg (23%), Mn (56%), Na (89%), Ni (56%), P (89%), and Zn (11%) exceeded the safety limits of National Environmental Quality standards (NEQs) of Pakistan. The results of Kelly's ratio (KR) classified surface water as unsuitable for irrigation. The average daily doses (ADD, mg/kg/day) for Al, Cu, Cr, Fe, Mn, Ni, and Zn were higher in children than in adults. The hazard index (HI) for children and adults was above the threshold (HI > 1), indicating a significant risk of non-carcinogenic toxicity. The carcinogenic risk values for Cr and Ni were above the USEPA limit (1 × 10-6 to 1 × 10-4), suggesting a potential carcinogenic risk for the target population. Principal component analysis (PCA), biplot (CLR), and the CoDa-dendrogram allowed for the identification of elemental associations, and their potential source was anthropogenic rather than natural in origin. Regular monitoring and phytoremediation strategies are proposed to safeguard crops and human health.

Ex-situ biological treatment of industrial saline seafood wastewater by salt-tolerant mixed cultures and phytotoxicity evaluation

In the framework of circular economy, this study assessed the ex-situ biodegradation and desalination of saline non-sterilized seafood wastewater (SFW) by new salt-tolerant mixed bacterial cultures, followed by its phytotoxicity evaluation. These cultures were characterized through 16S amplicon sequencing, an advanced tool to process the biodiversity of samples empowering applicability to advanced bioprocessing of SFW. The mixed cultures had high relative abundance of Pseudomonas and Aeromonas, and abundance of Acinetobacter, Myroides and Chryseobacterium. The biodegradation potential, growth kinetics and specific growth rate of the mixed cultures were determined using varying concentrations of SFW (20% and 80% v/v). The process was completed in just 24 h resulting in no odour and colour. The mixed cultures were also combined. Effective Chemical Oxygen Demand (COD) removal (36.2–89.1%) was achieved by the mixed cultures and their combinations. The mixed cultures resulted in significant salt content reduction (77.5–83.3%). The considerably lower levels of COD (<900 mg/L) and salt content achieved, in most cases, is a step towards in-situ SFW treatment before entrance to the sewage system. Among all, mixed Pseudomonas sp. dominant cultures were the most promising for further in-situ bioprocessing studies. In addition, the biotreated SFW supernatant, which was not overly-diluted using freshwater, could potentially be reused in agriculture, as the germination index was higher than 50% upon seed and root growth of tomato and lettuce. It contained approximately 0.03% total nitrogen and 0.01% phosphate which may irrigate to plants providing additional nutrients.

Determination of Coagulant Dosage and Stirring Time in Laboratory Wastewater Pretreatment

The use of chemicals in practical activities or research in the laboratory will certainly produce wastewater. Wastewater generated from the laboratory is classified as hazardous and/or toxic waste. Based on the substances contained in laboratory wastewater in terms of accumulated amount and a long period of time, wastewater will pollute the environment and will have an impact on living things around it if it is directly discharged into water bodies. The composition of laboratory waste is reactive and dangerous because it contains heavy metals Pb, Fe, and Cu as well as high Chemical Oxygen Demand (COD) and Total Suspended Solid (TSS) so it is difficult to decompose in nature. This study aimed to prepare the laboratory wastewater using the coagulation process as pretreatment. Therefore, this research prioritized the reduction of heavy metal levels of Pb, Fe, and Cu and reduced the content of COD and TSS with Alum as a coagulant. The highest degradation percentage of COD and TSS content occurred at the Coagulation Dose of 80 ppm, namely 99.79% and 99.80% respectively. Meanwhile, the highest degradation percentage of heavy metal levels of Pb, Fe, and Cu as well as the optimum COD and TSS content occurred at a stirring time of 60 minutes respectively, which were 49.48%, 58.96%, 94.09%, 99.97%, and 99.40%. It was concluded that the pretreatment of laboratory wastewater using the coagulation process could reduce the levels of Pb, Fe, and Cu metals, and the content of COD and TSS.

Comprehensively investigating performance and potential mechanism of anammox-based nitrogen removal process with different microbial morphologies under mainstream conditions

Achieving the stable operation of anammox-based wastewater treatment plants at comparatively low temperature and high organic concentrations is still a challenge. A limited number of studies have systematically investigated the performance of anammox-based systems with different microbial morphologies under mainstream conditions. Big data analysis of previous publications was performed. Based on this, we used various options to test wastewater treatment plant performance. Granule help the wastewater treatment system avoid the low temperature and mesophilic conditions. The next best option was biofilm, while the suspended sludge option performed the worst of all the treatment plants. The chemical oxygen demand concentration over 100 mg/L limited nitrogen removal. Higher temperatures however tempered this effect. The Spearman correlation analysis also verified the observed effects of temperature and organic matter on the efficiency of nitrogen removal. The calculated apparent activation energies of microorganisms in the granular sludge, the biofilm, the integrated fixed activated sludge (IFAS), and the suspended sludge were 26, 47, 118 and 120 kJ/mol, respectively. The granules and biofilm were more effective in treating the wastewater since they could resist the low and mesophilic temperatures. To predict the results of the nitrogen removal rate of the four different microbial morphologies, the Gaussian process regression model performed the best. When the correlation analysis was combined with the quantitative calculation, the inhibition ratio of low temperature on the anammox process was 63%, 91%, and 90% for the granular sludge, the biofilm, and the IFAS, respectively. We recommend using the granule morphology for wastewater treatment under mainstream conditions.