Field application of cost-effective sensors for the monitoring of NH3, H2S, and TVOC in environmental treatment facilities and the estimation of odor intensity.

Odor is usually a complex mixture of various compounds. In many countries, odor complaints have been addressed using the air dilution olfactory method (ADOM) to reduce their malodor complaint. In this study, continuous monitoring of ammonia, hydrogen sulfide, and total volatile organic compounds (TVOC) using sensors was conducted in facilities for municipal and livestock wastewater treatment (LWT), and for food waste composting (FWC). Odor intensity was modeled by multivariate linear regression using sensor monitoring data with air dilution measured by the ADOM. In testing the performance of sensors in the lab, all three sensors showed acceptable values for linearity, accuracy, repeatability, lowest detection limit, and response time, so the sensors were acceptable for application in the field. In on-site real-time monitoring, the three sensors functioned well in the three environmental facilities during the testing period. Average ammonia and hydrogen sulfide concentrations were high in the LWT facility, while TVOC showed the highest concentration in the FWC facility. A longer sampling time is necessary for ammonia monitoring. Odor intensity from individual sensor data correlated well to complex odor measured by the ADOM. Finally, we suggest a protocol for field application of sensor monitoring and odor data reproduction.Implications: We suggest a protocol for the field application of sensor monitoring and odor data estimation in this study. This study can be useful to a policy maker and field operator to reduce odor emission through the determination of a more effective treatment technology and removal pathway for individual odorants.

Oxidative potential of fine ambient particles in various environments.

The oxidative potential (OP) and chemical characteristics of fine particles collected from urban, roadside, rural, and industrial sites in Korea during spring, summer, fall, and winter seasons and an urban site in the Philippines during dry and wet seasons were examined. Significant differences in the OP of fine particles among sites and seasons were found. The industrial site yielded the highest OP activity (both mass and volume-normalized OP) among the sites, suggesting the strongest reactive oxygen species (ROS)-generating capability of industry source-dominant PM2.5. Seasonal data show that OP activities increased during the spring and summer possibly due to increased heavy metals caused by dust events and secondary organic aerosols formed by strong photochemical activity, respectively. The strength of the OP association with the chemical components highlights the influence of organic carbon and transition metals on the OP of ambient fine particles. The two OP assays (dithiothreitol (DTT) and electron spin resonance (ESR)) having different ROS-generating mechanisms were found to have different sensitivities to the chemical components facilitating a complementary analysis of the OP of ambient fine particles. Multiple linear regression model equations (OP as a function of chemical components) which were dependent on the sites were derived. A comparison of the daily OP and hazard index (HI) (the ratio of the measured mass concentration to the reference mass concentration of fine particles) suggests that the HI may not be sufficient to accurately estimate the health effects of fine particles, and a direct or indirect measurement of toxicity such as OP should be required in addition to the concentration level.

Potential application of Alcaligenes faecalis strain No. 4 in mitigating ammonia emissions from dairy wastewater.

This research examined the potential mitigation of NH3 emissions from dairy manure via an enhanced aerobic bio-treatment with bacterium Alcaligenes faecalis strain No. 4. The studies were conducted in aerated batch reactors using air and pure oxygen. Aeration with air and oxygen removed approximately 40% and 100% total ammoniacal nitrogen (TAN), respectively. Intermittent oxygenation (every 2 or 4 h) reduced oxygen consumption by 95%, while attaining nearly identical TAN removal to continuous aeration. The results revealed that adequate oxygen supply and supplementing dairy wastewater with carbon are essential for this bioprocess. Based on the nitrogen mass balance, only 4% of TAN was released as NH3 gas, while the majority was retained in either the microbial biomass (58%) or converted to nitrogen gas (36%). The mass balance results reveal high potential for environmentally friendly bio-treatment of dairy wastewater using A. faecalis strain No. 4 with respect to NH3 emissions.

Reliable low-cost devices for monitoring ammonia concentrations and emissions in naturally ventilated dairy barns.

This research investigated the use of two relatively cost-effective devices for determining NH3 concentrations in naturally ventilated (NV) dairy barns including an Ogawa passive sampler (Ogawa) and a passive flux sampler (PFS). These samplers were deployed adjacent to sampling ports of a photoacoustic infrared multigas spectroscope (INNOVA), in a NV dairy barn. A 3-day deployment period was deemed suitable for both passive samplers. The correlations between concentrations determined with the passive samplers and the INNOVA were statistically significant (r = 0.93 for Ogawa and 0.88 for PFS). Compared with reference measurements, Ogawa overestimated NH3 concentrations in the barn by ∼ 14%, while PFS underestimated NH3 concentrations by ∼ 41%. Barn NH3 emission factors per animal unit (20.6-21.2 g d(-1) AU(-1)) based on the two passive samplers, after calibration, were similar to those obtained with the reference method and were within the range of values reported in literature.

Mass concentration coupled with mass loading rate for evaluating PM(2.5) pollution status in the atmosphere: A case study based on dairy barns.

This study investigated particulate matter (PM) loading rates and concentrations in ambient air from naturally ventilated dairy barns and also the influences of pertinent meteorological factors, traffic, and animal activities on mass loading rates and mass concentrations. Generally, relationships between PM2.5 concentration and these parameters were significantly poorer than those between the PM loading rate and the same parameters. Although ambient air PM2.5 loading rates correlated well with PM2.5 emission rates, ambient air PM2.5 concentrations correlated poorly with PM2.5 concentrations in the barns. A comprehensive assessment of PM2.5 pollution in ambient air, therefore, requires both mass concentrations and mass loading rates. Emissions of PM2.5 correlated strongly and positively with wind speed, temperature, and solar radiation (R(2) = 0.84 to 0.99) and strongly but negatively with relative humidity (R(2) = 0.93). Animal activity exhibited only moderate effect on PM2.5 emissions, while traffic activity did not significantly affect PM2.5 emissions.

Reduction of volatile fatty acids and odor offensiveness by anaerobic digestion and solid separation of dairy manure during manure storage.

Volatile fatty acids (VFA) play an important role in the biodegradation of organic wastes and production of bioenergy under anaerobic digestion, and are related to malodors. However, little is known about the dynamics of VFA during dairy manure storage. This study evaluated the characteristics of VFA in dairy manure before and after anaerobic co-digestion in a laboratory experiment using eight lab-scale reactors. The reactors were loaded with four different types of dairy manure: (1) liquid dairy manure from a freestall barn, (2) mixture of dairy manure and co-digestion food processing wastes at the inlet of an anaerobic digester, (3) effluent from the digester outlet, and (4) the liquid fraction of effluent from a solid separator. Four VFA (acetic, propionic, butyric, and 2-methylbutyric acids) were identified and quantified in weekly manure samples from all reactors. Results showed that the dominant VFA was acetic acid in all four manure sources. The off-farm co-digestion wastes significantly increased the total VFA concentrations and the proportions of individual VFA in the influent. The dairy manure under storage demonstrated high temporal and spatial variations in pH and VFA concentrations. Anaerobic digestion reduced the total VFA by 86%-96%; but solid-liquid separation did not demonstrate a significant reduction in total VFA in this study. Using VFA as an indicator, anaerobic digestion exhibited an effective reduction of dairy manure odor offensiveness.

Bioremediation of oil-contaminated soil using Candida catenulata and food waste.

Even though petroleum-degrading microorganisms are widely distributed in soil and water, they may not be present in sufficient numbers to achieve contaminant remediation. In such cases, it may be useful to inoculate the polluted area with highly effective petroleum-degrading microbial strains to augment the exiting ones. In order to identify a microbial strain for bioaugmentation of oil-contaminated soil, we isolated a microbial strain with high emulsification and petroleum hydrocarbon degradation efficiency of diesel fuel in culture. The efficacy of the isolated microbial strain, identified as Candida catenulata CM1, was further evaluated during composting of a mixture containing 23% food waste and 77% diesel-contaminated soil including 2% (w/w) diesel. After 13 days of composting, 84% of the initial petroleum hydrocarbon was degraded in composting mixes containing a powdered form of CM1 (CM1-solid), compared with 48% of removal ratio in control reactor without inoculum. This finding suggests that CM1 is a viable microbial strain for bioremediation of oil-contaminated soil with food waste through composting processes.

Improvement in ammonium removal efficiency in wastewater treatment by mixed culture of Alcaligenes faecalis no. 4 and L1.

To improve ammonium removal efficiency in wastewater treatment, a mixed culture of Alcaligenes faecalis no. 4 and its mutant L1, both of which have heterotrophic nitrification and aerobic denitrification abilities, was performed. In a batch culture, no. 4 has a higher denitrification ability than L1, but its ammonium removal rate was lower. In a mixed continuous culture in the ammonium loading range of 750 to 3500 mg-N/l/d, the average ammonium removal rate and the average denitrification ratio were 61 mg-N/l/h and 31%, respectively. In the mixed culture, the ammonium removal rate was twofold higher than that in a single culture of no. 4, the rate was similar to that in a single culture of L1, and the denitrification ratio was very high compared with that in the single culture of L1.

Degradation of diesel oil in soil using a food waste composting process.

We investigated the simultaneous degradation of diesel oil in soil and the organic matter in food waste by composting in 8 l reactors. Using a 0.5 l/min air flow rate, and 0.5-1% diesel oil concentrations together with 20% food waste, high composting temperatures (above 60 degrees C) were attained due to the efficient degradation of the food waste. Petroleum hydrocarbons were degraded by 80% after only 15 days composting in the presence of food waste. In a 28 l reactor scale-up experiment using 1% oil, 20% food waste and 79% soil, removal efficiencies of petroleum hydrocarbons and food waste after 15 days were 79% and 77%, respectively.

Piggery wastewater treatment using Alcaligenes faecalis strain No. 4 with heterotrophic nitrification and aerobic denitrification.

Alcaligenes faecalis strain No. 4, which has heterotrophic nitrification and aerobic denitrification abilities, was used to treat actual piggery wastewater containing high-strength ammonium under aerobic conditions. In a continuous experiment using a solids-free wastewater (SFW) mixed with feces, almost all of the 2000 NH4+ -N mg/L and 12,000 COD mg/L in the wastewater was removed and the ammonium removal rate was approximately 30 mg-N/L/h, which was 5-10 times higher than the rates achieved by other bacteria with the same abilities. The denitrification ratio was more than 65% of removed NH4+ -N, indicating that strain No. 4 exhibited its heterotrophic nitrification and aerobic denitrification abilities in the piggery wastewater.

Characteristics of ammonium removal by heterotrophic nitrification-aerobic denitrification by Alcaligenes faecalis No. 4.

Alcaligenes faecalis no. 4 has heterotrophic nitrification and aerobic denitrification abilities. By taking the nitrogen balance under different culture conditions, 40-50% of removed NH4+-N was denitrified and about one-half of removed NH4+-N was converted to intracellular nitrogen. The maximum ammonium removal rate of no. 4 (28.9 mg-N/l/h) and its denitrification rate at high-strength NH4+-N of about 1200 ppm in aerated batch experiments at a C/N ratio of 10 were 5-40 times higher than those of other bacteria with the same ability. Only a few percent of the removed ammonium was converted to nitrite, and the main denitrification process was speculated to be via hydroxylamine which was produced by ammonium oxidation.

Nitrification and denitrification in high-strength ammonium by Alcaligenes faecalis.

Alcaligenes faecalis sp. No. 4, that has the ability of heterotrophic nitrification and aerobic denitrification in high-strength ammonium at about 1200 mg-N/l, converted about one-half of removed NH4+-N to intracellular nitrogen and nitrified only 3% of the removed NH4+. From the nitrogen balance, 40-50% of removed NH4+-N was estimated to be denitrified. Production of N2 was confirmed by GC-MS and 90% of denitrified products was N2. The maximum ammonium removal rate, 29 mg-N/l h and its denitrification rate in aerated batch experiments, were 5-40 times higher than those of other bacteria with the same ability.