A comprehensive understanding of saturation index and upflow velocity in a pilot-scale fluidized bed reactor for struvite recovery from swine wastewater

Tian

Water Environment Research

et al. 2020

As a promising strategy to remove and recover phosphorus from wastewater, optimization of the struvite (MgNH4PO4.6H2O) precipitation parameters is required to achieve desirable phosphorus removal efficiency. To tackle the challenges upon the precipitation optimization methods as three‐level full factorial designs, and central composite design as well, Box–Behnken design was implemented to optimize different reaction parameters for phosphorus removal and recovery during struvite precipitation in the current study. Moreover, the reaction orders and the rate equation were all determined to reveal the reaction kinetics parameters of struvite precipitation. The results showed that the optimal operating parameters of pH, Mg/P ratio and N/P ratio were 9.82, 1.45, and 4.00, respectively, by which more than 95% of phosphorus removal efficiency could be achieved. In addition, it was found that pH and pH/(N/P) had the most influence on phosphorus removal efficiency among different individual factors and interactive items, respectively. The partial orders of PO4‐P, Mg2+, and NH4+ in kinetic rate equation were determined as 1.586, 0.930, and 1.236 while the rate constant k was 0.0167 ± 0.0014 mM‐2.752 per minute by differential method. Practitioner points Different reaction parameters were optimized by Box–Behnken design. pH and pH/(N/P) had the most influence on phosphorus removal efficiency among different individual factors and interactive items. The reaction orders and the rate equation were all determined to reveal the reaction kinetics parameters.

Section: Introductionmentioning

confidence: 99%

Optimization and reaction kinetics analysis for phosphorus removal in struvite precipitation process

Tian

Water Environment Research

et al. 2020

J of Chemical Tech & Biotech

“…The formation of struvite is conditioned by several physicochemical parameters such as pH, temperature, chemical composition of wastewater and a combination of factors such as the presence of crystal seeds, thermodynamics and mass transfer between solid and liquid phases 114 . For struvite precipitation, technologies like stirred tank and fluidised bed reactors are the most widely used 115 . These techniques not only alleviate the scale problem in wastewater treatment plants, but also provide a pelletisable fertiliser product, showing both environmental and economic benefits 115 .…”

Section: Biorefinery Productsmentioning

confidence: 99%

“…114 For struvite precipitation, technologies like stirred tank and fluidised bed reactors are the most widely used. 115 These techniques not only alleviate the scale problem in wastewater treatment plants, but also provide a pelletisable fertiliser product, showing both environmental and economic benefits. 115 Münch and Barr 116 reported that a treatment plant can recover 1 kg of struvite from 100 m 3 of wastewater.…”

Section: Struvite Precipitationmentioning

confidence: 99%

Biorefineries at poultry farms: a perspective for sustainable development

Odales-Bernal

Schulz

González

et al. 2020

Poultry litter (PL) is one of the drier and bulkier manures produced in intensive agriculture. Land spreading is considered the most common treatment option for PL; however, this causes large atmospheric greenhouse emissions and consequently a high negative environmental impact. PL has several factors that limit its sustainable use as an energy source, and thus there is still a need for more studies about sustainable waste management. The paper aims at: (i) proposing sustainable pathways in order to maximise the PL valorisation process, based on previous experiences described in the literature; and (ii) showing the advantages of reforming poultry farms into biorefineries in Cuba. Combinations of techniques are used to increase PL valorisation, but only by modulating the theoretical data has an improvement occurred. In this work, pathways for thermo‐ and bioconversion processes are proposed which involve four major technologies for converting PL into useful energy and fertiliser, being pyrolysis/gasification, hydrothermal carbonisation and anaerobic digestion as key conversion technologies. Including technologies for nutrient recovery in the proposed pathways would allow better agricultural applications. The treatment of PL in biorefineries in Cuba would have a positive impact on the economy through income generation and savings resulting from reductions in imports (i.e. fossil fuels and agrochemicals), employment creation, improved living conditions and development in rural communities. Future studies should be aimed at evaluating the various proposed pathways in order to maximise the PL valorisation process, in addition to a marketing study of the products generated through the biorefineries at poultry farms. © 2020 Society of Chemical Industry (SCI)

“…The effectiveness of the struvite recovery process depends on the reactor type as well as its recovery efficiency and recovered product quality [10]. Li et al [11] provided information on the different reactors investigated for struvite crystallization.…”

Section: Introductionmentioning

confidence: 99%

Design and Optimization of Fluidized Bed Reactor Operating Conditions for Struvite Recovery Process from Swine Wastewater

et al. 2020

Struvite crystallization using fluidized bed reactors (FBRs) is one of the most commonly used methods for nutrient recovery from different waste streams. However, struvite recovery from swine wastewater containing much higher solids using FBR has not been studied extensively. In this study, we therefore designed and optimized the key operating conditions parameters, i.e., pH (9.0, 9.5, and 10.0), circulation rate (CR) (1.5, 3.0, and 4.5 L/Lreactor·h), and hydraulic retention time (HRT) (1, 3, and 5 h) of FBR to ensure efficient nutrient removal and struvite crystallization from swine wastewater using response surface methodology (RSM) with central composite design (CCD) as experimental design. A magnesium/phosphorus (Mg/P) molar ratio of 1.3 was maintained with MgCl2 according to ortho-phosphate (O-P) concentration of influent and an air diffuser was set to supply air with 0.03 L air/Lreactor·min. The O-P recovery efficiency of over 91% was achieved through the entire runs. Among the operational parameters, pH did not show any significant effect on NH4-N recovery, particle size, and struvite production rate (SPR). The optimal CR over 2.94 L/Lreactor·h was found to be appropriate for efficient removal of nutrients and struvite crystallization. While optimizing the HRT, priority of the process operation such as the production of larger struvite particles or increased struvite productivity should be considered. Therefore, the optimal operational parameters of pH 9.0, CR > 2.94 L/Lreactor·h, and HRT of 1 or 5 h were chosen to obtain better responses through RSM analyses. The findings of this study would be useful in designing and operating either pilot- or full-scale FBR for struvite crystallization from swine wastewater.