Emission of Volatile Organic Compounds during

Water Air Soil Pollut DOI 10.1007/s11270-007-9406-0

Emission of Volatile Organic Compounds during Composting of Poultry Litter N. G. Turan & A. Akdemir & O. N. Ergun\

Received: 17 November 2006 / Accepted: 1 April 2007 # Springer Science + Business Media B.V. 2007

Abstract The objective of this study was to identify and quantify volatile organic compounds (VOCs) produced during composting of poultry litter. The VOCs produced from in-vessel composting with a controlled aeration system were tested using the F-ITR method by VOC analyzer. Alkanes and alkylated benzenes were emitted in the highest amounts from poultry litter, while aldehydes, terpenes, ketones were emitted in much lesser amounts. Studies showed that VOCs generation was the greatest early during the composting process and greatly reduced thereafter. Composting temperatures were found to affect VOCs. All VOCs were least with the high temperatures generated during composting. Keywords Poultry litter . Composting . VOCs . Odors

N. G. Turan (*) : A. Akdemir : O. N. Ergun Department of Environmental Engineering, Ondokuz Mayis University, 55139 Samsun, Turkey e-mail: [email protected] A. Akdemir e-mail: [email protected] O. N. Ergun e-mail: [email protected]

1 Introduction Poultry litter is a mixture of excreta, feed, feathers and a bedding material (Stephenson et al. 1990; Gupta et al. 1997). The composition of poultry litter depends on feed type, bedding material used and pest control methods (van der Watt et al. 1994). Poultry litter is primarily disposed of by land application as a fertilizer due to presence of nitrogen (3.3% NO3), phosphorous (3.4% P2O5) and potassium (1.7% K2O) (Gupta et al. 1997). The aqueous leachate of poultry litter is known to exhibit toxicity to various organisms. Leaching of N and P into water bodies causes eutrophication and algal blooms. Furthermore, poultry litter may elevate the concentration of certain metals such as Cu and Zn in the exchangeable fraction of the soil (Li and Shuman 1997). Also, further risk from long term application of poultry litter is the likely shift in soil forms of P from organic to predominantly more weakly bound inorganic forms, the latter being more prone to run-off (Sharpley and Smith 1995). The land application of litter may result in the uptake of the toxicants by plants, animals and humans through absorption, ingestion, bioaccumulation, or other processes. Composting is an acceptable and recommended means of recycling organic wastes and is rapidly gaining acceptance in the world as a method for stabilizing/sanitizing poultry wastes. However, composting of poultry wastes can present unique problems

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because the organics may still contain 70–80% water. The presence of so much water in poultry wastes can result in reduced composting temperatures, odors and volatile organic compounds (VOCs) production if moisture is not controlled. Many odorous compounds and VOCs are formed during anaerobic periods. If a facility is designed properly, anaerobic conditions can be avoided through careful management of the composting process. Poultry litter has high nitrogen content. The presence of excess nitrogen is caused low C/N ratio. An improper nutrient balance in the poultry litter can lead to excessive VOCs (Williams 1995; Heining et al. 1995; Smet et al. 1999). The environmental problem caused by the presence of VOCs in gaseous streams is due to the fact that many of them produce bad odors or are hazardous. Eye and throat irritation, damage to liver, central nervous system, all may occur due to the prolonged exposure to VOCs. VOCs may also carcinogenic effects (Das et al. 2004). In addition, VOCs can contribute to global warming, stratospheric ozone depletion and tropospheric ozone formation (Komilis et al. 2004). For this reason VOCs are being subject to increasingly severe constrains; in Europe, for example, VOCs are controlled through the EU Directive 1999/ 13/EC on the limitation of emissions of volatile organic compounds (Pagans et al. 2006). More information on VOCs data is needed. No published data on VOCs were found for poultry litter composting facilities. Such information would enable facilities to modify their design and manage operations to reduce potential negative impacts on the environment. The objectives of this work were to identify and quantify selected VOCs emitted during in-vessel composting of poultry wastes.

Table 1 Characteristics of the poultry litter Parameters

Units

Mean values

PHa Moisture contenta E. conductivitya TKNb NH3–Nb NO3−–Nb Total carbon contentb C/N

– % mS/cm % mg/l mg/l % –

8.4±0.2 75.5±2.0 19.68±0.12 3.14±0.18 44.8±2.3 6.3±0.3 42.5±1.4 13.5

a

All values were determined in dried matter

b

All values were determined in original matter

2.2 Experimental Set-up To compost waste, in a vessel prototype composter was constructed of an open-ended glass bin with a volume of 25 l. The bin’s equipment enables, measurement of temperature, aeration of system and outlet of gas (Fig. 1). Substrates were aerated via forced aeration using an air pump. Bin was filled with ±12 kg poultry litter. Bin was covered with insulating material to minimise heat losses. The temperature in the composting material was measured via a temperature probe. Experiments were carried out continuously for 100 days. The sampling period was chosen ones a week. 2.3 Analytical Methods VOCs were analyzed by using a MIRAN® 205B series SapphlRe model portable ambient air analyzer.

4

2 Materials and Methods

5 2

2.1 Substrate

1

Poultry litter, a mixture of bedding, excreta, feathers, and spilled feed, was collected from a 200,000capacity poultry facility. The litter stored under dry conditions until composting after removal from the production facility. The chemical analysis of the poultry litter is given in Table 1.

Fig. 1 Set-up of the pilot-scale composting experiment: (1) composting bin, (2) composting material, (3) air pump, (4) temperature probe, (5) effluent air

3

Water Air Soil Pollut Table 2 List of VOCs targeted for quantification

SapphIRe analyzer uses fundamental principles openpath fourier transform infrared (FT-IR) spectroscopy. This method is referred to EPA’s Methods for the Determination of Toxic Organic Compounds in Ambient Air, (EPA-TO-16). The SapphlRe analyzer reports the number of VOCs in the sampled air. Each gas has a different partial pressure and, thus, a different wavelength frequency that can be detected by the instrument. Once analyzed, the results are recorded as parts per million. Twenty-five VOCs were targeted for further quantification. These VOCs were selected because of their availability in the animal wastes. The selected VOCs were listed in Table 2. 2.4 Statistics All analyses were carried out in triplicate and results given are the averages with standard deviations.

Accuracya Compound (±% of name reading)

Accuracya (±% of reading)

Acetaldehyde Acetic acid Acetone Acetylene Benzaldehyde Benzene 1,3-Butadiene Carbon dioxide Chlorobenzene Cyclohexane

10 20 5 10 15 10 10 15 10 10

10 10 15 25 10 10 10 15 10 10

Cyclopentane

10

Ethyl benzene Heptane

15 10

Isobutane Methyl chloride Methyl ethyl ketone Octane Pentane n-Propanol Pyridine Styrene Toluene 1,1,2Trichloroethane 1,1,2,2Tetrachloroethane Xylene

10 15

a

Accuracy is defined as ± the average value displayed from five times the detection limit to the full scale reading.

3 Results and Discussion

maintained at 55°C or higher for 3 days (EPA 1994). The temperature of the composting studied did not reach the thermophilic phase. The maximum temperature reached was 54°C for 1 day. This may be due to the high compaction of the solid poultry litter, creating anaerobic conditions that did not permit the growth of aerobic thermophilic microorganisms. VOCs were identified in the gaseous emissions of the run using portable ambient air analyzer. Cumulative production of sum of 25 VOCs during compost-

3.1 VOCs Emitted during Composting During the process the temperature was monitored, but only the maximum temperature is reported weekly. Figure 2 shows the evolution of temperature during the composting. Using either the within-vessel composting method or the static aerated pile composting method, the temperature of the biosolids is 16000

60

VOCs Emissions (mg/m3)

14000

VOCs Emissions Temperature

12000

50

40

10000 8000

30

6000 20 4000 10

2000 0

0 0

1

2

3

4

5

6

7 8 9 Time (weeks)

10

11

12

13

14

15

Temperature (¼C)

Fig. 2 Cumulative production of sum of 25 VOCs during composting of poultry litter

Compound name


ing of poultry litter are presented in Fig. 2. VOCs concentration in the composting exhaust gases ranged from 411 to 14,547 mg/m3 for poultry litter. As it can be seen in Fig. 2, the volatile organic compounds (VOCs) emitted were greatest during the initial composting, but dropped off dramatically before the curing phase. Maximum observed concentrations of VOCs emitted from poultry litter and threshold limit values are included in Table 3. The TLV is a timeweighed average concentration for a normal 8-h work day and a 40-h work week to which all workers are exposed daily without adverse effects (Epstein 1997). Poultry litter emitted high amounts of xenobiotic VOCs (alkanes, alkylated benzenes) right after initiation of the run indicating that these compounds can be a result of deposition as well as a result of decomposition. Alkane (heptane, isobutene, pentane, octane) concentrations increased in less than 5 days and then decreased with the high temperatures generated during

composting. Heptane, isobutene and pentane were not detected after the first week. However, octane was measured in relatively low concentrations during the composting process. Alkylated benzenes (toluene, ethylbenzene, xylene, styrene) were detected the highest relative concentrations from the poultry litter composting process. These compounds had been also identified by Wilkins (1994), Eitzer (1995), Tolvanen et al. (1998), and Komilis et al. (2004) in the headspace of mixed wastes. Aromatic hydrocarbons were emitted in the highest amounts in poultry litter composting process. From the aromatic hydrocarbons particularly, benzene and toluene were identified in the run, as a result of microbial process. In the process, an increased toluene and benzene releases were observed upon transition from the mesophilic to the thermophilic stage. These VOC emissions decreased during the composting process. Aromatic hydrocarbons, common composting facilities air pollutants, were emitted in the highest

Table 3 Maximum observed concentration and threshold limit value of VOCs (in mg m−3) TLVa

Acetaldehyde Acetic acid Acetone Acetylene Benzaldehyde Benzene 1,3-Butadiene Chlorobenzene Cyclohexane Cyclopentane Ethyl benzene Heptane Isobutane Methyl chloride Methyl ethyl ketone Octane Pentane n-Propanol Pyridine Styrene Toluene 1,1,2-Trichloroethane 1,1,2,2-Tetrachloroethane Xylene

117±12 6±0.6 2 037±39 13±1.2 203±11 571±21 72±5.4 235±8.5 825±14.3 338±6.4 713±12.7 2 087±45.2 175±7.1 255±9.3 925±11.3 4 501±23.2 3 220±18.4 927±11.3 989±16.5 73±4.4 744±10.3 366±7.1 276±9.1 103±8.7

180 25 1,780 Not listed Not listed 30 Not listed 350 1,050 1,720 435 1,600 Not listed 175 590 1,450 1,800 500 15 215 375 45 Not listed 435

a

American Conference of Governmental Industrial HygienistsThreshold Limit Value (Eitzer 1995; Epstein 1997)

a Concentration of CO2 (mg g-1)

Maximum observed concentration

100 90 80 70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (weeks)

b Amount of cumulative CO2 (mg g-1)

Compound name

350 300 250 200 150 100 50 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Time (weeks)

Fig. 3 Changes in CO2 evolution (a) and cumulative amount of CO2 (b) during composting of poultry litter


amounts from poultry litter, while aldehydes were emitted in much lesser amounts. Alcohols, terpenes, ketones, acids and sulfides are typical microbial byproducts (Wilkins and Larsen 1995). According to Homans and Fischer (1992), mainly anaerobic conditions in composting piles due to incomplete or insufficient aeration will produce sulphur compounds of intensive smell, while incomplete aerobic degradation processes result in the emission of alcohols, ketones, esters and organic acids. Terpenes and ketones were the most prevalent VOCs emitted from poultry litter as a result of microbial peocesses. Terpenes have been widely found in several degradation environments (Komilis et al. 2004). Acids and sulfides were not detected in this work. On the other hand, the fact that microbial processes are precursors of certain biogenic VOCs was clearly indicated by the relatively low alcohol concentration. Several chlorinated aliphatic and chlorinated aromatics, such as chlorobenzene, methyl chloride, 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane were in negligible amounts in the run. Pyridine was the principle N containing compound detected and its presence is attributed to microbial degradation. This VOC emission increased to the termophilic temperatures and then decreased during the composting process of poultry litter.

amount of CO2 evolution for the process observed that decomposition of biodegradable raw organic matter was vigorous during the first 40 days because up to 90% of the cumulative CO2 respiration took place in this period (Fig. 3b). The respiration rate at the end of the composting process was 1.11 mg/g poultry litter.

4 Conclussions Organic compounds can be volatilized during composting, resulting in odors. Some compounds are the result of microbial degradation, others are compounds found in the feedstock. Emission of volatile compounds started upon arrival of the fresh poultry litter to the composting process. The VOCs maximum production was obtained in the first 5 days. Most of the volatile organic compounds in composting were emitted at early stages of processing. It was also observed a decreasing concentration of almost all VOCs from fresh to composted poultry litter. Further research lines in this field should be focused on the removal of VOCs from composting process. Acknowledgements This work was financed by a scholarship of the Ondokuz Mayıs University for support of Scientific/ Technological Research (Project MF-102). The authors thankfully acknowledge Ernur Chicken Farming for supplying the poultry litter samples to conduct the present study.

3.2 CO2 Evolution References In Figs. 2a and b, the gradual decrease in microbial respiration rate during the composting of poultry litter. Contents of CO2 in the exhaust of the process reached maximum evolutions within 3–5 days, which coincided with the rise in temperature and the beginning of thermophilic phase (Fig. 3a). The maximum amounts of CO2 evolution were 91.79 in the run. Following the initial rise, CO2 content decreased significantly at day 5 which was presumably due to the thermal inhibition of microbiological activities and the decrease in readily soluble nutrients (Viel et al. 1987). After 5 weeks, the respiration rate of CO2 was less than 5 mg/g for the process, which indicated that compost was considered relatively stable after this composting period (Garcia et al. 1992; Epstein 1997). The cumulative CO2 respiration was 29.011 mg/g poultry litter during the composting. The cumulative

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