Ammonia Recovery from Livestock Manure Digestate through an Air-Bubble Stripping Reactor: Evaluation of Performance and Energy Balance

Abbà, Alessandro; Domini, Marta; Baldi, Marco; Pedrazzani, Roberta

doi:10.3390/en16041643

Cited by 8 publications

(8 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Table 3 shows the effect of AS on the final characteristics of DRS and DD after 24 h of Test 1. As it is possible to observe from Figure 1, PA gradually decreased along the treatment for both DRS and DD, while the IA of DRS remained higher than 6000 mg CaCO 3 L −1 after 24 h. The PA decrease allowed for CO 2 stripping, thus reducing the bicarbonate and carbonate ion content and the buffer capacity of the matrix [13,21]. CO 2 volatilization led to an increase in pH [11] and to a shift in the ammonia dissociation equilibrium (NH 4 + ↔ NH 3 + H + ), which depends on pH and temperature, towards the free ammonia nitrogen (FAN) production [31].…”

Section: Air Stripping Efficiency On Raw Cattle Slurry and The Liquid...mentioning

confidence: 87%

See 1 more Smart Citation

Ammonia Air Stripping from Different Livestock Effluents Prior to and after Anaerobic Digestion

et al. 2023

View full text Add to dashboard Cite

Livestock digestate provides nutrients and organic matter to the soil while increasing agricultural sustainability. Nevertheless, nitrogen (N) losses due to the nutrient surplus in regions characterized by intensive animal farming activities still represent an unsolved issue. For this purpose, digestate needs proper treatment and management to avoid N losses in the environment. In the livestock farming context, anaerobic digestion (AD) can be accompanied by an ammonia stripping (AS) process for N recovery. This paper aims to investigate the feasibility AS prior to and after AD of the manure, focusing on two different livestock farms, representative of dairy cattle and pig breeding in southern Italy. AS was performed at a lab scale by injecting microbubbles of air, which allowed the pH to increase, and thus the removal of ammonia. The results show that treating a dairy raw slurry with high intermediate alkalinity (IA) (6707 mg CaCO3 L−1) with AS may not be convenient in terms of total ammonia nitrogen (TAN) reduction. As a matter of fact, the loss of buffering capacity during the stripping process resulted in a pH never exceeding the value of 9, which could not promote free ammonia volatilization, whereas integrating AD with AS allowed us to obtain a 34% higher TAN reduction under the same stripping conditions at a temperature (T) of 38 °C and a gas-to-liquid ratio (G/L) of 1:1. Therefore, the AS removal efficiency strongly depends on the characteristics (mainly IA) of the treated matrix. High IA values suggest a possible high concentration of volatile fatty acids, which hinders pH increases and, thus, enables ammonia stripping. Despite the initial matrix origin, a low IA compared to the total alkalinity (TA) (<20% of TA) ensures a greater ammonia removal efficiency, which could be similar between digestate and raw manure in the same operative process conditions. Nonetheless, the amount of ammonia stripped is related to the initial TAN concentration of the specific matrix.

show abstract

Section: Air Stripping Efficiency On Raw Cattle Slurry and The Liquid...mentioning

confidence: 87%

“…According to the specific aim, an AS tower could precede the AD reactor or come in succession. Nevertheless, AS could be affected by the formation of fouling during the process and elevated energy and chemical requirements for an increase in pH [21].…”

Section: Introductionmentioning

confidence: 99%

Ammonia Air Stripping from Different Livestock Effluents Prior to and after Anaerobic Digestion

et al. 2023

View full text Add to dashboard Cite

show abstract

“…Several technologies have been tested to recover ammonium from livestock manure, such as nutrient chemical precipitation in the form of struvite [2,3], water evaporation [4,5], the use of hydrophobic membranes [6][7][8] and other mostly emergent technologies, e.g., bioelectrochemical systems [9,10]. One of the most extended technologies for ammonia recovery is air stripping and absorption [11][12][13]. This process is based on the ammoniumammonia equilibrium (Reaction (1)).…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Vacuum Evaporation of Ammonia from Pig Slurry at Laboratory and Pilot-Plant Scale

Cerrillo,

Moreno,

Burgos

et al. 2023

Processes

View full text Add to dashboard Cite

Livestock manure has a high ammonium content that can limit its direct application on soil as a fertiliser in nitrate-vulnerable zones. Treatment technologies that are able to extract ammonium from livestock manure allow it to be concentrated in small volumes, making it cheaper and easier to transport and use as fertiliser in crop areas where there is a deficit of nitrogen. This study proposed using low-temperature vacuum evaporation to treat pig slurry in order to obtain marketable products that can be used as fertilisers and help close the nitrogen cycle. Two different configurations and scales were used. The first was a seven-litre laboratory-scale evaporator complemented with a condenser, a condensate trapper, an acid trap and a vacuum pump operated at −90 kPa vacuum pressure and at three different temperatures: 50.1 ± 0.2 °C, 46.0 ± 0.1 °C and 45.3 ± 1.3 °C. The second, Ammoneva, is an on-farm pilot-scale evaporator (6.4 m3), capable of working in four-hour batches of 1 t of liquid fraction of pig slurry with an operating temperature of 40–45 °C and −80 kPa vacuum pressure. The laboratory-scale evaporator, which features several novel improvements focused on increasing ammonia recovery, showed a higher nitrogen removal efficiency from the liquid fraction of pig slurry than the on-farm pilot plant, achieving 84% at 50.1 °C operation, and recovering most of it in ammonia solution (up to 77% of the initial nitrogen), with 7% of the ammonia not recovered. The Ammoneva pilot plant achieved a treated liquid fraction with 41% of initial nitrogen on average, recovering 15% in the ammonia solution in the acid trap; so, the NH3 gas absorption step needs to be further optimised. However, due to the simplicity of the Ammoneva pilot plant, which is easily placed inside a 20-foot container, and the complete automation of the process, it is suitable as an on-farm treatment for decentralised pig slurry management. The implementation of the novel design developed at laboratory-scale could help further increase recovery efficiencies at the pilot-plant scale.

show abstract

“…In this process, ammonia is removed from the liquid fraction by flowing air through the bulk. This technology has been successfully applied to digestate [17][18][19], landfill leachate [20,21], and wastewater [22]. Alkali addition may be required in order to raise the pH and optimize the process, which involves expenses for the chemicals [23].…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, these technologies have some limitations, such as the consumption of energy for heating the digestate, alkali to adjust the pH, scaling and fouling (due to the formation of calcium carbonate on the surface of packing materials), which can affect ammonia removal efficiencies over time [16,24]. To overcome some of these disadvantages, alternative technologies such as jet loop and aero-cyclone reactors [24], semi-batch jet loop reactors [26], water spray reactors [27], and air bubble reactors [18,28] are being implemented and studied. In particular, bubble reactors have the main advantage of not being sensitive to fouling, and it has been demonstrated that, working under sufficiently high temperature (above 60 • C), the dosage of alkaline reagents may be prevented [18].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Main Parameters Influencing the Kinetics of an Ammonia Stripping Plant Treating Swine Digestate

et al. 2023

Self Cite

View full text Add to dashboard Cite

Ammonia stripping is a consolidated technology that can be adopted to reduce the excessive content of nitrogen in the digestate, thus allowing its reuse as fertilizer within the maximum nitrogen loads set by regulations. In this work, the role of the main operational parameters (airflow and temperature) was assessed on a pilot bubble reactor treating a swine-based digestate, under batch conditions. A kinetic model was developed to correlate temperature, airflow and the ammonia removal yield. Varying the temperature from 60 to 70 °C and the airflow rate from 30 to 60 m3air h−1 m−3digestate, the performance of the plant was measured at different reaction times. The process was favored by the spontaneous pH increase over 10, without basifying agent addition. The lowest removal efficiency (50%) was recorded at 60 °C and 30 m3air h−1 m−3digestate. A removal efficiency higher than 80% was reached running the process at 70 °C and 45 or 60 m3air h−1 m−3digestate. Performance curves were than developed as a practical tool to identify the operating conditions leading to a desired nitrogen removal rate: for instance, under the most severe conditions, up to 80% ammoniacal nitrogen could be removed in about 10 h. Though the obtained results are valid for the treated digestate, the experimental methodology as well as the mathematical model could be replicated in other case studies, thus allowing the amelioration of the process operation.

show abstract

Ammonia Recovery from Livestock Manure Digestate through an Air-Bubble Stripping Reactor: Evaluation of Performance and Energy Balance

Cited by 8 publications

References 37 publications

Ammonia Air Stripping from Different Livestock Effluents Prior to and after Anaerobic Digestion

Ammonia Air Stripping from Different Livestock Effluents Prior to and after Anaerobic Digestion

Low-Temperature Vacuum Evaporation of Ammonia from Pig Slurry at Laboratory and Pilot-Plant Scale

Investigation of the Main Parameters Influencing the Kinetics of an Ammonia Stripping Plant Treating Swine Digestate

Contact Info

Product

Resources

About