Influence Of Wastewater Composition Research Articles

Phosphorus recovery from fertilizer industrial wastewaters using bittern: Influence of wastewater composition and pH on struvite formation

Effluent from fertilizer-manufacturing facility contains a large amount of nutrients. In this study, wastewater was used to synthesize fertilizer-grade struvite through reaction with a bittern solution (denoted as R-B). The produced struvite was compared with different wastewater composition, including wastewater with added MgCl2.6H2O (R-Mg) and artificial wastewater with bittern solution (A-B). The results showed that the nutrient recovery of R-B was comparable to that of R-Mg sample, in which N and P were recovered by 64–68 % and 89–91 %, respectively. The nutrient recovery is feasible for crystallized struvite employing bittern. Energy-dispersive X-ray mapping profiles and X-ray diffraction revealed that the presence of impurities in real wastewater effect the crystal size and have attracted more mixed ions into struvite crystals. The solubility testing showed that N release in acidic and water was 23.3 wt% and 6.8 wt% after 60 days, indicating that the struvite was an extremely slow-soluble fertilizer for agricultural applications.

BIO_ALGAE 2: improved model of microalgae and bacteria consortia for wastewater treatment.

A new set up of the integral mechanistic BIO_ALGAE model that describes the complex interactions in mixed algal-bacterial systems was developed to overcome some restrictions of the model. BIO_ALGAE 2 includes new sub-models that take into account the variation of microalgae and bacteria performance as a function of culture conditions prevailing in microalgae cultures (pH, temperature, dissolved oxygen) over daily and seasonal cycles and the implementation of on-demand dioxide carbon injection for pH control. Moreover, another aim of this work was to study a correlation between the mass transfer coefficient and the hydrodynamics of reactor. The model was calibrated using real data from a laboratory reactor fed with real wastewater. Moreover, the model was used to simulate daily variations of different components in the pond (dissolved oxygen, pH, and CO2 injection) and to predict microalgae (XALG) and bacteria (XH) proportions and to estimate daily biomass production (Cb). The effect of CO2 injection and the influence of wastewater composition on treatment performance were investigated through practical study cases. XALG decreased by 38%, and XH increased by 35% with respect to the system under pH control while microalgae and bacteria proportions are completely different as a function of influent wastewater composition. Model simulations have indicated that Cb production (~ 100gTSSm-3day-1 for manure and centrate) resulted lower than Cb production obtained using primary influent wastewater (155gTSSm-3day-1).

Influence of wastewater composition on nutrient removal behaviors in the new anaerobic–anoxic/nitrifying/induced crystallization process

In this study, the new anaerobic–anoxic/nitrifying/induced crystallization (A2N–IC) system was compared with anaerobic-anoxic/nitrifying (A2N) process to investigate nutrient removal performance under different influent COD and ammonia concentrations. Ammonia and COD removal rates were very stable in both processes, which were maintained at 84.9% and 86.6% when the influent ammonia varied from 30mgL−1 to 45mgL−1 and COD ranged from 250mgL−1 to 300mgL−1. The effluent phosphorus always maintained below 0.2mgL−1 in A2N–IC, whereas in A2N the effluent phosphorus concentration was 0.4–1.7mgL−1, demonstrating that A2N–IC is suitable to apply in a broader influent COD and ammonia concentration range. Under higher influent COD (300mgL−1) or lower ammonia conditions (30mgL−1), the main function of chemical induced crystallization was to coordinate better nutrient ratio for anoxic phosphorus uptake, whereas under high phosphorus concentration, it was to reduce phosphorus loading for biological system. Under the similar influent wastewater compositions, phosphorus release amounts were always lower in A2N–IC. To clarify the decrease procedure of phosphorus release in the A2N–IC, the equilibrium between chemical phosphorus removal and biological phosphorus removal in A2N–IC was analyzed by mass balance equations. During the long-term experiment, some undesirable phenomena were observed: the declining nitrification in post-aerobic tank and calcium phosphorus precipitation in the anaerobic tank. The reasons were analyzed; furthermore, the corresponding improvements were proposed. Nitrification effect could be enhanced in the post-aerobic tank, therefore ammonia removal rate could be increased; and biologically induced phosphorus precipitation could be inhibited by controlling pH at the anaerobic stage, so the phosphorus release and recovery could be improved.

Influence of wastewater composition on biological nutrient removal in UniFed SBR process

The effects of influent C/N ratio and C/P ratio on biological nutrient removal performance were investigated in a lab-scale UniFed SBR apparatus treating real domestic wastewater. The results showed that TN removal efficiency increased as C/N ratio increased from 43.6% at 2.8 to 80.8% at 5.7. But when C/N ratio increased further, TN removal efficiency increased very slowly. This was because when C/N ratio was higher than 5.7, complete denitrification in the sludge blanket during feed/decant period had been achieved, TN removal efficiency during this period always kept the maximum value and only TN removal efficiency during aeration period rose as C/N ratio increased. PO(4) (3-) removal efficiency increased as C/N ratio increased from 27.3% at 2.8 to 88.1% at 5.7. When C/N ratio was 6.5 and above, PO(4) (3-) concentration couldn't be detected in the effluent. When influent C/N ratio and volumetric exchange ratio were fixed at 6 and 33% respectively, as C/P ratio was higher than 33, PO(4) (3-) concentration of effluent always remained below the detection level and phosphorus removal efficiency kept stable at 100%, but as the C/P ratio was lower than 33, phosphorus removal efficiency increased as C/P ratio increased linearly. C/P ratio hardly affected TN removal efficiency, which always kept at 82.2%-85.8% in this study.

Influence of wastewater composition on denitrification and biological P-removal in the S-DN-P-process: Effects of different substrates (a)

The influence of the wastewater composition on the denitrification and biological P-elimination in the Sorption Denitrification P-eliminations Process (S-DN-P-process) was examined. Batch type experiments were performed to examine the influence of various substrates. Among the three different substrates prepared, only 11% COD(filt) was taken up from starch containing wastewater (starch preparation). Acetate is an easily degradable substrate for the biological P-elimination, and showed ca. 30% more acetate was taken up compared to the raw wastewater (wastewater preparation). Starch is a barely degradable substance, because it must be hydrolysed before digestion. Starch initially sorbs slowly (approximately 30 min), and may be hydrolysed during this time. During the investigations, the biological P-elimination and the denitrification were found to be dependent on the wastewater composition. The P-elimination rate was determined to be 38% with the acetate preparation, while a P-elimination of 6% was obtained with the starch preparation. The wastewater preparation showed a P-elimination of 56%, the value of which was almost 18% more than the acetate preparation. The biological P-elimination and denitrification depend not only on the dissolved parts in the wastewater, but also on the undissolved content.

Influence of wastewater composition on nitrogen and phosphorus removal and process control in A2O process

A bench-scale anaerobic-anoxic-oxic (A2O) bioreactor with steady denitrifying phosphorus removal performance was tested to determine the influence of influent C/N ratio (SCOD/TN) and C/P ratio (SCOD/TP) on biological nutrient removal for treating synthetic brewage wastewater; meanwhile, the spatial profiles of DO, pH and ORP sensors in such systems were investigated. The results showed that influent C/N ratio had significant effect on the TN, TP removal efficiencies and the ratio of anoxic to aerobic P uptake amount. The maximal TN and TP removal efficiencies could be achieved when influent C/N ratio was kept at about 7.1 and 5, respectively. Besides, the ratio of anoxic to aerobic P uptake amount was found to be linearly dependent on the influent C/N ratio with coefficient R2 of 0.685 when total recirculation ratio was constant at 3.5. Influent C/P ratio had an important effect on the TP removal efficiency, while it hardly affected TN removal efficiency. In addition, the TP removal efficiency reached the maximum for influent C/P ratio of 42. On the other hand, it was also found that the typical profiles of DO, pH and ORP sensors could be observed, and they have similar trends at the different influent C/N ratio and C/P ratio. It was suggested that the operational state could be well known according to the changes of simple on-line sensors.

Panus tigrinus efficiently removes phenols, color and organic load from olive-mill wastewater

This study was aimed at assessing the potential of the white-rot fungus Panus tigrinus CBS 577.79 in removing organic load, color and toxic phenols from agro-industrial effluent olive-mill wastewater (OMW). The influence of wastewater composition on P. tigrinus degradative capability was investigated in shaken cultures using two different OMWs. The initial soluble COD of 85 000 mg l −1 led to a delay in removal of color, organic load and phenol by the fungus. This was associated with delayed onset of laccase and Mn-dependent peroxidase. On the other hand, P. tigrinus, when grown on OMW with an initial soluble COD content of 43 000 mg l −1, promptly and efficiently removed the aforementioned components. Chromatographic analyses showed that 4-hydroxy-substituted simple phenols were predominantly removed. The polymeric aromatic fraction underwent simultaneous polymerization and depolymerization. This study is a contribution to the understanding of the degradative specificity of P. tigrinus on OMW aromatic components and provides good indications for possible future applications of the fungus.

Modelling of an Intermittently Aerated Completely Mixed Activated Sludge Reactor

Mathematical models for description of dynamic behaviour of simultaneous nitrification and denitrification processes carried out in an intermittently aerated completely mixed activated sludge reactor (CMASR) are presented. The general IAWPRC activated sludge model has been extended with volatilisation process of wastewater impurity. The influence of wastewater composition on oxygen transport rate is also included. Different approaches for dissolved oxygen incorporation in biochemical reaction kinetics have been applied. Determination of some biokinetic parameter values by evaluating steady-state measurements of process variables is implied in one version of the proposed models. Experimental modelling of simultaneous nitrification and denitrification processes, carried out in an industrial Carrousel activated sludge reactor, was performed in the lab-scale intermittently aerated CMASR. Organic, ammonium, and heavy metal shock loads were applied in order to simulate transient behaviour of the lab-scale reactor and the influence of heavy metal on biochemical processes and biokinetic parameter values has been investigated. Dissolved oxygen concentration in activated sludge reactor, COD, ammonium, nitrate and biomass concentration responses of reactor were measured and evaluated. Good agreement between the observed data and calculated values by verified models has been achieved. Estimated values of biokinetic parameters, found by optimisation procedure, are close to those recommended for simulation of domestic wastewater treatment processes. The applicability of the IAWPRC kinetic and stoichiometric concept for dynamic behaviour description of an intermittently aerated CMASR reactor, including the above mentioned extension and modification, is demonstrated in the work.

Influence of waste water composition on biofilm development in laboratory methanogenic fluidized bed reactors

The influence of the volatile fatty acid composition of waste waters on biofilm development and on the time course of reactor start-up was investigated in laboratory scale fluidized bed reactors. It was found that biofilm development proceeded in a similar way with either acetate, butyrate, propionate or a mixture of these compounds as carbon source in the waste water. Startup was retarded, however, with propionate as sole carbon source. Scanning electron microscopic examination revealed that immobilization of bacteria on the sand used as adhesive support initially occurred in crevices and that thereupon the surface of the sand particles became colonized. The composition of the newly developed biomass was determined when reactors reached steady state. Significant differences in the relative substrate spectra and in the amounts of hydrogenotrophic and acetotrophic methanogenic bacteria were measured. The differences reflected the differences in the composition of the waste waters. The results obtained emphasize the role of the structure of the carrier surface in start-up of methanogenic fluidized bed reactors.