Effect Of Wastewater Composition Research Articles

Treatment of sludge hydrothermal carbonization wastewater by ferrous/sodium percarbonate system: Effect of wastewater composition and role of coagulation and oxidation

It is crucial to explore the effect of complex wastewater compositions on the ferrous/sodium percarbonate (Fe(Ⅱ)/SPC) system and the role of oxidation-coagulation in designing water treatment processes. This study employed redundancy analysis to investigate the effects of wastewater constituents on oxidation and coagulation. Raman analysis, X-ray Photoelectron Spectroscopy, and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry were used to determine the roles of oxidation and coagulation in the system. The results showed that sulfates and phosphates formed amorphous complexes with iron species via coprecipitation, thereby promoting coagulation to remove organics. Some heavy metals can also be removed by coagulation. The co-activation of SPC by pre-existing transition metals and the added Fe(Ⅱ) facilitated the oxidative removal of organics, while chloride and arsenic were the main inhibitory inorganic substances in the system. Aromatic compounds mainly promoted coagulation, polysaccharides promoted oxidation, humic acid promoted oxidation and coagulation, and C=C/C=O inhibited the Fe(Ⅱ)/SPC system. The oxidation process removed graphitic structures and unsaturated organic matter in the region of (O/C, H/C) = (0.2–0.4, 0.9–2.0) through free radicals and generated amorphous carbon structures and saturated organic matter in the region of (O/C, H/C) = (0.3–0.7, 1.2–1.9). The coagulation process removed aromatic organics with 2–5 rings and unsaturated organics in the region of (O/C, H/C) = (0.2–0.6, 0.7–1.6) with oxygen-containing organics. The combined effects of coagulation and oxidation enhanced the removal efficiency of organic carbon by approximately 40%. This study facilitates the optimization of hydrothermal carbonization wastewater treatment and advanced oxidation processes.

Effects of wastewater composition and reactor operating mode on the removal of micropollutants via electrochemical advanced oxidation

When implementing an electrochemical Advanced Oxidation Process (eAOP) for wastewater treatment, the composition of the wastewater to be treated and the selection of the reactor operating mode are key parameters to be considered given their strong influence on the degradation kinetics, energy consumption, operating costs and environmental impacts. To this end, this study investigated the degradation of carbamazepine (CBZ) in different matrices (i.e., pure water vs. synthetic secondary effluent, high vs. low organic/ion content, single vs. multicomponent systems) and under several reactor operating modes (i.e., batch, fed-batch and continuous). The key findings of this research are (i) the self-cleaning capabilities that naturally occurring ionic species in wastewater (i.e., sulfate and nitrate ions) offer even if present at low concentrations and (ii) the significant performance implications resulting from the reactor operation selection. By combining both insights, this study illustrates the opportunities for developing more efficient eAOPs where no additional chemicals are needed, and hence, where secondary waste streams can be mitigated, while energy consumption is minimized and degradation efficiency is enhanced. In particular, treating CBZ-polluted secondary wastewater effluent in fed-batch mode could lead to up to a 2.1-fold increase in degradation and a 60 % reduction in energy with respect to a batch equivalent, despite the hindering effects that competition reactions from other wastewater constituents entailed.

Nutrient removal in an algal membrane photobioreactor: effects of wastewater composition and light/dark cycle.

Graesiella emersonii was cultivated in an osmotic membrane photobioreactor (OMPBR) for nutrients removal from synthetic wastewater in continuous mode. At 1.5days of hydraulic retention time and under continuous illumination, the microalgae removed nitrogen (N) completely at influent NH4+-N concentrations of 4-16mg/L, with removal rates of 3.03-12.1mg/L-day. Phosphorus (P) removal in the OMPBR was through biological assimilation as well as membrane rejection, but PO43--P assimilation by microalgae could be improved at higher NH4+-N concentrations. Microalgae biomass composition was affected by N/P ratio in wastewater, and a higher N/P ratio resulted in higher P accumulation in the biomass. The OMPBR accumulated about 0.35g/L biomass after 12days of operation under continuous illumination. However, OMPBR operation under 12h light/12h dark cycle lowered biomass productivity by 60%, which resulted in 20% decrease in NH4+-N removal and nearly threefold increase in PO43--P accumulation in the OMPBR. Prolonged dark phase also affected carbohydrate accumulation in biomass, although its effects on lipid and protein accumulation were negligible. The microalgae also exhibited high tendency to aggregate and settle, which could be attributed to reduction in cell surface charge and enrichment of soluble algal products in the OMPBR. Due to a relatively shorter operating period, membrane biofouling and salt accumulation did not influence the permeate flux significantly. These results improve the understanding of the effects of N/P ratio and light/dark cycle on biomass accumulation and nutrients removal in the OMPBR.

Shifts in bacterial community composition and abundance of nitrifiers during aerobic granulation in two nitrifying sequencing batch reactors

Shifts in bacterial community composition and abundance of nitrifiers during aerobic granulation, and the effects of wastewater composition on them were investigated using Illumina sequencing and quantitative PCR. The bacterial diversity decreased sharply during the post-granulation period. Although cultivated with different wastewater types, aerobic granular sludge (AGS) formed with similar bacterial structure. The bacterial structure in AGS was completely different from that of seed sludge. The minor genera in seed sludge, e.g., Arcobacter, Aeromonas, Flavobacterium and Acinetobacter, became the dominant genera in AGS. These genera have the potential to secrete excess extracellular polymer substances. Whereas, the dominant genera in seed sludge were found in less amount or even disappeared in AGS. During aerobic granulation, ammonia-oxidizing archaea were gradually washed-out. While, ammonia-oxidizing bacteria, complete ammonia oxidizers and nitrite-oxidizing bacteria were retained. Overall, in this study, the bacterial genera with low relative abundance in seed sludge are important for aerobic granulation.

Separation of ammonia from radioactive wastewater by hydrophobic membrane contactor

The radioactive wastewater produced in the manufacturing process of UO2 kernel for high temperature gas-cooled reactor (HTR) contains high concentration of ammonia. The ammonia has to be removed effectively for further treatment of the wastewater. In this study, the hydrophobic membrane contactor (HMC) was adopted to remove and recover the ammonia from radioactive wastewater at room temperature. The operating parameters such as feed velocity and initial ammonia concentration were determined. In addition, the effect of wastewater composition on ammonia separation was studied. The experiment results showed that ammonia removal efficiency could reach above 90% after 120 min operation when pH was not adjusted. While the initial pH of wastewater was adjusted to 12.0, ammonia removal efficiency could reach above 95%. The ammonia mass transfer coefficient increased with increase of feed velocity and tended to an asymptotic value when the feed velocity reached 0.049 m/s. When the initial ammonia concentration was 2211.6 mg/L, 5864.6 mg/L and 23,898.7 mg/L, the ammonia removal efficiency was 95.0%, 94.2% and 94.1%, respectively after 120 min operation, i.e. the initial concentration of ammonia in wastewater had almost no effect on ammonia separation. In addition, the coexisting substances, such as urea and tetrahydrofurfuryl alcohol (THFA), also had no effect on ammonia separation. The HMC is a promising way to separate ammonia from radioactive wastewater.

Influence of wastewater treatment plants' operational conditions on activated sludge microbiological and morphological characteristics

The effect of wastewater composition and operating conditions in activated sludge (AS) microbiological and morphological characteristics was studied in three AS wastewater treatment plants (WWTPs): (a) a high organic load slaughterhouse AS WWTP, operating at complete solids retention, monitored from its start-up and for 425 days; (b) a seasonally operational, low nitrogen load fruit canning industry AS WWTP, operating at complete solids retention, monitored from its start-up and until the end of the season (87 days); (c) a municipal AS WWTP, treating wastewater from a semi-combined sewer system, monitored during the transitions from dry to rainy and again to dry periods of operation. The sludge microbiological and morphological characteristics were correlated to nutrients' availability, solids retention time, hydraulic retention time, dissolved oxygen, mixed liquor suspended solids (MLVSS), organic load (F/M) and substrate utilization rate. The AS WWTPs' operation was distinguished in periods based on biomass growth phase, characterized by different biological and morphological characteristics and on operational conditions. An anoxic/aerobic selector minimizes the readily biodegradable compounds in influent, inhibiting filamentous growth. Plant performance controlling is presented in a logic flowchart in which operational parameters are linked to microbial manipulation, resulting in a useful tool for researchers and engineers.

Membrane treatment of liquid wastes from radiological decontamination operations

The paper focuses on the evaluation of membrane filtration for the treatment of liquid radioactive streams generated in area decontamination operations. In this work, semi-permeable membranes were demonstrated to be effective reducing the volume of wastewater containing cesium and cobalt by two orders of a magnitude. The efficiency of membrane separation was enhanced by employing additives that enlarged the size of target radionuclide species and improved their rejection by the membranes. This was achieved by chelation with synthetic water-soluble polymers and by adsorption on micro particles of adsorbent coupled with micelle formation. The effect of wastewater composition and that of the radionuclide-binding additives on the volume reduction was investigated. Membrane treatment is expected to help simplify further processing and decrease disposal costs.

Effect of wastewater composition on archaeal population diversity

Distribution and occurrence of Archaea and methanogenic activity in a laboratory scale, completely mixed anaerobic reactor treating pharmaceutical wastewaters were investigated and associated with reactor performance. The reactor was initially seeded with anaerobic digester sludge from an alcohol distillery wastewater treatment plant and was subjected to a three step feeding strategy. The feeding procedure involved gradual transition from a glucose containing feed to a solvent stripped pharmaceutical wastewater and then raw pharmaceutical wastewater. During the start-up period, over 90% COD removal efficiency at an organic loading rate (OLR) of 6 kg COD m −3 d −1 was achieved with glucose feeding, and acetoclastic methanogenic activity was 336 ml CH 4 gTVS −1 d −1. At the end of the primary loading, when the feed contained solvent stripped pharmaceutical wastewater at full composition, 71% soluble COD removal efficiency was obtained and acetoclastic methanogenic activity decreased to half of the rate under glucose feed (166 ml CH 4 gTVS −1 d −1). At the end of secondary loading with 60% (w/v) raw pharmaceutical wastewater, COD removal dropped to zero and acetoclastic methanogenic activity fell to less than 10 ml CH 4 gTVS −1 d −1. Throughout the course of the experiment, microbial community structure was monitored by DGGE analysis of 16S rRNA gene fragments. Five different archaeal taxa were identified and the predominant archaeal sequences belonged to methanogenic Archaea. Two of these showed greatest sequence identity with Methanobacterium formicicum and Methanosaeta concilii. The types of Archaea present changed little in response to changing feed composition but the relative contribution of different organisms identified in the archaeal DGGE profiles did change.

Effect of Wastewater Composition on Methanogenic Activity in an Anaerobic Reactor

In this study, effects of a chemical synthesis-based pharmaceutical wastewater on activity of acetoclastic methanogens within a lab-scale anaerobic completely stirred tank reactor (CSTR) were investigated. The CSTR was initially fed with glucose and loaded up to an organic loading rate of 6 kg COD m−3 d−1 at which 92% soluble COD removal efficiency was achieved. Acetoclastic methanogenic activity was found to be 336 mL CH4 gTVS−1 d−1. The CSTR was then, fed with several dilutions of preaerated wastewater with glucose at 10% wt v−1, 30% wt v−1, and 70% wt v−1 ratios and followed by 100% wt v−1 preaerated wastewater. In the latter, 71% soluble COD removal efficiency was obtained and a maximum acetoclastic methanogenic activity was 166 mL CH4 gTVS−1 d−1. Finally, raw wastewater diluted with preaerated wastewater was fed into the CSTR in increasing ratios of 10–60% wt v−1. Total failure of anaerobic reactor was observed at 60% wt v−1 raw wastewater fed. The study was, therefore, discontinued due to poor acetoclastic methanogenic activity of reactor sludge which was totally distorted.

Effect of Wastewater Composition on Methanogenic Activity in an Anaerobic Reactor

Effect of Wastewater Composition on Methanogenic Activity in an Anaerobic Reactor

Effect of Wastewater Composition on the Development of an Activated Sludge Biological Phosphorus Removal System

A biological system for P removal has been developed by using an A/O (anaerobic/aerobic) activated sludge process with a sequencing batch reactor operation mode. The effect of three kinds of synthetic wastewater with different organic composition has been studied. Evolution of sludge and effluent characteristics from the original sludge to steady state conditions were studied, and P and COD profiles during batch A/O cycles were also analysed. A fast P accumulation in the sludge was detected during the previous acclimation phases. The presence of higher concentrations of easily biodegradable products improved the acclimation process and increased the rate at which a conventional activated sludge was transformed into a phosphorus accumulating microorganism enriched sludge. The steady state P content of the sludge increased and the VSS concentration decreased in all cases. Acetate in wastewater caused bad sludge settling and soluble starch caused slow evolution to steady state conditions. Different stoichiometric ratios of mg P released per mg COD removed in the anaerobic phase were observed. Depending on the substrate used, it is possible that a decrease of Bio-P bacteria number by the development of another group of microorganisms without P accumulation activity, should be observed. This ratio, and the P sludge content, increased when the wastewater was composed by easier biodegradable products.

Effect of wastewater composition on microbial populations in biological phosphorus removal processes

Bench-scale sequential batch reactors (SBRs) were fed with glucose- and acetate-containing synthetic wastewaters to evaluate microbial population dynamics and types of phosphorus-accumulating organisms (PAOs) using a cellular fatty acid profile analysis. The phosphorus content in the sludge was 38% (w/w) for the acetate-fed SBR and 20% (w/w) for the glucose-fed SBR with a VSS/TSS ratio of 50%. Glucose-fed PAOs were found to remove phosphorus with accumulation of glycogen in cells without synthesizing poly-β-hydroxybutyrate (PHB) at influent phosphorus concentration < 20 mg-P/L and nitrate concentration < 2 mg-N/L. From the fatty acid profile biomarker study, it was found that the glucose-fed SBR maintained the same fatty acid profile before and after biological phosphorus removal (BPR) occurred while the acetate-fed SBR had a different fatty acid profile. The microbial population in the glucose-fed SBR was significantly different in terms of metabolic behavior and cellular fatty acid profile from that introduced in the acetate-fed SBR. Fatty acid a15:0 (anteiso methyl-branching) was abundant in the glucose-fed PAOs. Among the five PAO candidates (Acinetobacter, Pseudomonas, Arthrobacter, Aeromonas, and Micrococcus), only Arthrobacter spp. had the biomarker of fatty acid a15:0, indicating that Arthrobacter spp. may be one of the PAOs existing in the glucose-fed bioreactors.

Effect of wastewater composition on microbial populations in biological phosphorus removal processes

Bench-scale sequential batch reactors (SBRs) were fed with glucose- and acetate-containing synthetic wastewaters to evaluate microbial population dynamics and types of phosphorus-accumulating organisms (PAOs) using a cellular fatty acid profile analysis. The phosphorus content in the sludge was 38% (w/w) for the acetate-fed SBR and 20% (w/w) for the glucose-fed SBR with a VSS/TSS ratio of 50%. Glucose-fed PAOs were found to remove phosphorus with accumulation of glycogen in cells without synthesizing poly-β-hydroxybutyrate (PHB) at influent phosphorus concentration < 20 mg-P/L and nitrate concentration < 2 mg-N/L. From the fatty acid profile biomarker study, it was found that the glucose-fed SBR maintained the same fatty acid profile before and after biological phosphorus removal (BPR) occurred while the acetate-fed SBR had a different fatty acid profile. The microbial population in the glucose-fed SBR was significantly different in terms of metabolic behavior and cellular fatty acid profile from that introduced in the acetate-fed SBR. Fatty acid a 15:0 (anteiso methyl-branching) was abundant in the glucose-fed PAOs. Among the five PAO candidates (Acinetobacter, Pseudomonas, Arthrobacter, Aeromonas, and Micrococcus), only Arthrobacter spp. had the biomarker of fatty acid a15:0, indicating that Arthrobacter spp. may be one of the PAOs existing in the glucose-fed bioreactors.

Effect of wastewater composition on treatment performance of a column bioreactor with recycle

Effect of synthetic wastewater composition on COD removal performance of a continuous column bioreactor with recycle was studied. Zooglea ramigera was used as dominant microbial culture throughout the experiments. Synthetic wastewater was composed of diluted molasses, urea, KH2PO4 and MgSO4. Wastewater composition was changed by adjusting influent COD/N/P ratio between 100/7/1-100/15/1. System was operated with nitrogen and COD limitations and COD removal performances were compared. Both nitrogen and COD removal efficiencies and rates were calculated and optimum feed COD/N ratio was determined to be between 100/8-100/10.

Effect of wastewater composition on treatment performance of a column bioreactor with recycle

Effect of wastewater composition on treatment performance of a column bioreactor with recycle

Effects of Wastewater Composition on Stability of UASB

Three types of wastewater based on acetate, sucrose, and ice cream were used to investigate the long‐term effect of wastewater composition on the stability of the upflow anaerobic sludge blanket (UASB) process using laboratory‐scale reactors. Experimental results revealed that variations in the carbon source in the wastewater caused gradual changes in both the physical structures and the bacterial distribution of the seeding granular sludge, which resulted in disintegration or floatation of the granular sludge under certain conditions. The rate of such changes was found to be relatively slow, and depended on the sludge‐loading rate. A semiquantitative mathematical model on the ecological characteristics of the granular sludge was developed and was able to explain the experimental results. The study suggests that the failure of the UASB process under certain circumstance was primarily due to the limitation in the ecological structure of the granular sludge.