RESUMEN
The microwave-enhanced advanced oxidation process (MW-AOP) was utilized for the treatment of liquid dairy manure, prior to anaerobic digestion (AD). A significant amount of soluble chemical oxygen demand (SCOD) was formed in the treated solution, but there was no or little increase in volatile fatty acid (VFA). In this study, up-flow anaerobic sludge blanket (UASB) reactors were used in both the conventional AD system and as the methane phase reactor in a two-phase anaerobic digestion (TPAD) system. Both AD systems were capable of operating at very short hydraulic retention times (HRTs) to as low as about 3 days, and very high methane production rates were achieved. However, much higher methane production was obtained in the TPAD system. The phase separation of the acidogenesis and the methanogenesis in the TPAD system not only increased methane production but also maintained reactor stability throughout the experimental period. Thus, the combination of MW-AOP treatment and TPAD appears to be an effective means of energy recovery from dairy manure.
Asunto(s)
Estiércol , Microondas , Anaerobiosis , Aguas del Alcantarillado , Metano , Reactores BiológicosRESUMEN
The microwave enhanced advanced oxidation process (MW-AOP) has been applied to pre-treat different sludge types and high solids content. Secondary sludge not only had the highest solids and nutrient content but also yielded higher treatment efficiency than primary or mixed sludge. In the case of secondary sludge with 4% total solids (TS), the total suspended solids (TSS) concentration was reduced by 32% while soluble chemical oxygen demand concentration increased from 1% to 40% after treatment at 110°C. A high level of nutrient release was also achieved; about 65% total phosphate (TP) solubilized at 110°C. The degree of secondary sludge disintegration was dictated by temperature and hydrogen peroxide dosage. The optimal operating temperature for the system was 110°C, and sludge containing TS up to 8% was treated effectively. Secondary sludge with 8% TS had a TSS reduction of 41% after treatment at 110°C while COD solubilization was about 45%; about 55% TP was solubilized at 10â min holding time. Treatment of sludge with higher solids content would allow for handling larger amounts of sludge at a given period and reduce heating cost per unit of treated sludge. The inter-relationship between the degree of sludge disintegration and changes in chemical and physical properties was also clearly demonstrated here. The treated sludge would be an ideal substrate for anaerobic digestion or phosphorous recovery processes. High levels of nutrients (phosphorus and nitrogen) and metal release, and solids disintegration from sludge containing high solids content would make subsequent resource recovery processes more effective and economical.
Asunto(s)
Microondas , Aguas del Alcantarillado , Aguas del Alcantarillado/química , Oxidación-Reducción , Peróxido de Hidrógeno/química , Temperatura , Fosfatos/química , FósforoRESUMEN
Mixtures of fats, oils and grease (FOG) either with dairy manure or with thickened waste secondary sludge (TWSS) were treated using microwave enhanced advanced oxidation process (MW-AOP). For both dairy manure and TWSS mixtures, the maximum increase in soluble COD (SCOD) resulted from the 1:1 mixture by total solids (TS) weight. In the TWSS mixtures, production of volatile fatty acid (VFA) increased with greater FOG content, while there was a decreasing production trend in VFA in dairy manure mixtures. Nutrients and metals were also released for all sets. The degradation followed peroxidation mechanism to produce lower molecular weight substrates such as short-chain fatty acids which would be less inhibitory to microbes. Nutrients and metals in the treated solution would sustain microbial growth in a biological system. FOG content for the mixtures in the MW-AOP treatment should be less than 75% by TS weight to prevent oxidation to CO2.
Asunto(s)
Microondas , Aguas del Alcantarillado , Estiércol , Aceites , Oxidación-ReducciónRESUMEN
BACKGROUND: Liquid organic fertilizers (LOFs) are relatively easier to degrade than those of solid organic fertilizers, and the nutrients are readily available for plant uptake. Microwave enhanced advanced oxidation treatment (MW/H2 O2 -AOP) was used to convert solid organic fertilizers (insoluble blood meal, bone meal, feather meal, sunflower ash and a mixture) into LOF. RESULTS: After the MW/H2 O2 -AOP treatment, high soluble nitrogen (11-29%), soluble phosphorus (64%) and potassium (92%), as well as low total suspended solids content could be obtained. The resulting LOF would make the nutrients more bioavailable, and would provide some of them for the plant uptake immediately. Temperature and hydrogen peroxide dosage were found to be significant factors affecting nitrogen release from blood meal and feather meal, while temperature and pH were found to be significant factors for solubilizing phosphorus and potassium from bone meal and ash, respectively. CONCLUSION: The MW/H2 O2 -AOP reduced suspended solids, and released nutrients into solution; therefore, it was an effective treatment method to make LOFs. © 2016 Society of Chemical Industry.
Asunto(s)
Fertilizantes/análisis , Residuos/análisis , Microondas , Nitrógeno/química , Agricultura Orgánica/instrumentación , Oxidación-Reducción/efectos de la radiación , Fósforo/química , Aguas del Alcantarillado/químicaRESUMEN
Microwave digestion of liquid dairy manure was tested for the release of nutrients, such as orthophosphates, ammonia-nitrogen, magnesium, calcium and potassium, both with and without the aid of an oxidizing agent (hydrogen peroxide). The orthophosphate to total phosphorus ratio of the manure increased from 21% to greater than 80% with 5 minutes of microwave treatment. More than 36% of total chemical oxygen demand (t-COD) of the manure was reduced when microwave digestion was assisted with peroxide addition. In addition, the volatile fatty acids (VFAs) distribution shifted to simpler chain acids (acetic acid in particular) with an increase in operating temperature. In the second part of the study, digested manure with increased soluble phosphate was tested for the recovery of struvite (magnesium ammonium phosphate) at different pH. It was found that up to 90% of orthophosphate can be removed from the solution. Overall, it was concluded that the oxidizing agent-assisted microwave digestion process can be used upstream of anaerobic digestion, following which the anaerobically digested manure can be used for struvite recovery. Thus, this microwave digestion process presents the potential for enhanced efficiencies in both manure digestion and struvite recovery.
Asunto(s)
Compuestos de Magnesio/análisis , Estiércol/análisis , Microondas , Fosfatos/análisis , Fósforo/química , Fósforo/efectos de la radiación , Administración de Residuos/métodos , Animales , Bovinos , Industria Lechera/métodos , Digestión , Contaminación Ambiental/análisis , Contaminación Ambiental/prevención & control , Femenino , Peróxido de Hidrógeno/química , Concentración de Iones de Hidrógeno , Compuestos de Magnesio/química , Compuestos de Magnesio/efectos de la radiación , Oxidación-Reducción , Fosfatos/química , Fosfatos/efectos de la radiación , Suelo/análisis , Microbiología del Suelo , Solubilidad , Estruvita , Factores de TiempoRESUMEN
Solids destruction and nutrients release from sewage sludge were investigated using thermal destruction and/or oxidation processes. Hydrogen peroxide (H(2)O(2)), ozone (O(3)) and a combination of both were used for the oxidation processes performed at ambient temperature. Thermal destruction using microwave (MW) alone without an oxidant was also conducted. Microwave enhanced advanced oxidation processes (MW-AOP), such as MW/O(3), MW/H(2)O(2) and MW/H(2)O(2)/O(3), were conducted at 100 degrees C. In terms of nutrients release and solids reduction, the MW/H(2)O(2)/O(3)-AOP yielded the best result; an addition of ozone improved the MW-AOP process. More than 30% of TP and 20% of TKN were released into the solution. About 37% of total COD was also solubilized from sludge mass. Both the conventional oxidation processes and the MW-AOP processes could be used to release nutrients and to reduce solids from sewage sludge; however, the MW-AOP processes were superior in performance. Microwave heating alone also resulted in a substantial amount of ortho-phosphate into the solution.
Asunto(s)
Peróxido de Hidrógeno/farmacología , Microondas , Ozono/farmacología , Aguas del Alcantarillado , Oxidación-ReducciónRESUMEN
A full-scale sequencing batch reactor (SBR) system was evaluated for its ability to remove carbon and nitrogen from swine wastewater. The SBR was operated on four, six-hour cycles each day, with each cycle consisting of 4.5 hours of "React," 0.75 hours of "Settling", 0.75 hours for "Draw" and "Fill." Within each cycle, an amount of wastewater equivalent to about 5% of the reactor volume (5,500 litres) was removed and added. The SBR system was able to remove 82% of biochemical oxygen demand (BOD) and more than 75% of nitrogen. Even though the SBR effluent, with an average effluent BOD5 of about 588 mg L(-1), did not meet the discharge criteria, it enabled a reduction of the land base required for land application of swine wastewater by about 75%. Results indicated that the SBR system was a viable method for the treatment of swine wastewater.
Asunto(s)
Reactores Biológicos , Carbono/análisis , Nitrógeno/análisis , Eliminación de Residuos Líquidos/métodos , Anaerobiosis , Crianza de Animales Domésticos/métodos , Animales , Reactores Biológicos/microbiología , Carbono/metabolismo , Nitrógeno/metabolismo , PorcinosRESUMEN
A combined approach of biological treatment, solids digestion and nutrient recovery was tested on dairy manure. A sequencing batch reactor (SBR) was operated in three modes, in order to optimize nutrient (nitrogen and phosphorus) removals. The highest average removal efficiencies of 91% for NH4-N, 59% for PO4-P and 80% for total chemical oxygen demand (COD) were achieved. Staining experiments suggested the coexistence of glycogen and phosphorus accumulating organisms. Anaerobic digestion of wasted bio-solids was able to produce a PO4-P concentration of 70 mgL-1 in the supernatant. A pilot-scale experiment, designed to recover phosphorus in the supernatant as struvite (magnesium ammonium phosphate), was able to remove 82% of soluble PO4-P.
Asunto(s)
Estiércol , Nitrógeno/aislamiento & purificación , Oxígeno/metabolismo , Fosfatos/aislamiento & purificación , Animales , Reactores Biológicos , Bovinos , Digestión , Femenino , Compuestos de Magnesio/análisis , Compuestos de Magnesio/aislamiento & purificación , Nitrógeno/análisis , Fosfatos/análisis , Solubilidad , Estruvita , Factores de Tiempo , Administración de Residuos/métodosRESUMEN
Both the advanced oxidation process (AOP) using a combination of hydrogen peroxide addition and microwave heating (H2O2/microwave), and the microwave heating process were used for solubilization of phosphorus from liquid dairy manure. About 80% of total phosphate was released into the solution at a microwave heating time of 5 min at 170 degrees C. With an addition of H2O2, more than 81% of total phosphate could be released over a reaction period of 49 h at ambient temperature. The AOP process could achieve up to 85% of total phosphate release at 120 degrees C. The results indicated that both the microwave, and the AOP processes could effectively release phosphate from liquid dairy manure. These processes could serve as pretreatments for phosphorus recovery from animal wastes, and could be combined with the struvite crystallization process to provide a new approach in treating animal wastes.
Asunto(s)
Peróxido de Hidrógeno/química , Estiércol/análisis , Microondas , Fósforo/química , Fósforo/efectos de la radiación , Animales , Bovinos , Contaminación Ambiental/análisis , Contaminación Ambiental/prevención & control , Oxidación-Reducción , Fósforo/análisis , Solubilidad , Ácidos Sulfúricos/química , Factores de TiempoRESUMEN
An advanced oxidation process (AOP) combining hydrogen peroxide and microwave heating was used for the solubilization of phosphate from secondary municipal sludge from an enhanced biological phosphorus removal process. The microwave irradiation is used as a generator agent of oxidizing radicals as well as a heating source in the process. This AOP process could facilitate the release of a large amount of the sludge-bound phosphorus from the sewage sludge. More than 84% of the total phosphorous could be released at a microwave heating time of 5 min at 170 degrees C. This innovative process has the potential of being applied to simple sludge treatment processes in domestic wastewater treatment and to the recovery of phosphorus from the wastewater.
Asunto(s)
Peróxido de Hidrógeno/química , Microondas , Fosfatos/análisis , Aguas del Alcantarillado/química , Purificación del Agua/métodos , Oxidación-Reducción , Fosfatos/química , Fosfatos/efectos de la radiación , Solubilidad , Purificación del Agua/instrumentaciónRESUMEN
Phosphorus recovery from greenhouse wastewater, using precipitation-crystallization, was conducted under three levels of calcium concentration, 304 mg/L (7.6 mmol/L), 384 mg/L (9.6 mmol/L), and 480 mg/L (12 mmol/L), and also with additions of ammonium and magnesium into the wastewater. Jar test results confirmed high phosphate removal, with more than 90% of the removal achieved with a pH as low as 7.7. Under the low calcium concentration, ammonium addition affected the chemical reactions at pH lower than 8.0, where struvite was produced; when the pH was raised to 8.8, other calcium compounds dominated the precipitation. Under the medium calcium concentration, ammonium and magnesium addition helped struvite precipitation in the low pH range. Hydroxyapatite (HAP) was the main product. Under the high calcium concentration, ammonium addition showed no effects on the precipitation.