Production of composted recycled manure solids from a Canadian dairy farm: Impact on microbial air quality in experimental conditions

Figures & data

Figure 1. A confined and independently ventilated experimental chamber with a polyethylene drainage pipe on its concrete floor (a) filled with 0.67 m³ of RMS (b). For the turned windrow composting method, RMS were daily turned (c). Airborne dust, endotoxins and microorganisms were sampled with a DustTrak^TM DRX Aerosol Monitor (TSI) and a SASS®3100 Dry Air Sampler (Research International) on days 0 (pipe filling with RMS), 5 (5-day aging of RMS) and 10 (10-day aging of RMS) (d)

Table 1. Primers and probes used for PCR quantification of selected microorganisms

Microorganisms	Sequences from 5ʹ to 3ʹ^1	References
Total bacteria	F – GGTA GTC YAY GCM STA AAC G R – GGT TAC CTT GTT ACG ACT T P – 56-FAM/TKC GCG TTG/ZEN/CDT CGA ATT AAW CCA C/3IABkFQ	(Bach et al. 2002)
Escherichia coli	F – GTT AAT ACC TTT GCT CAT TGA T R – ACC AGG GTA TCT AAT CCT GT	(Malinen et al. 2003)
Escherichia coli O157:H7	F – TCG AGC GGA CCA TGA TCA R – GGC GGC GTC TGA GAT AAC A P – 56-FAM/AGA ACT TCA/ZEN/AAT CCA TCA TT/3IABkFQ	(Shannon et al. 2007)
Klebsiella pneumoniae	F – CCT GGA TCT GAC CCT GCA GTA R – CCG TCG CCG TTC TGT TTC P – 56-FAM/CAG GGT AAA/ZEN/AAC GAA GGC/3IABkFQ	(Shannon et al. 2007)
Legionella sp.	F – CTA ATT GGC TGA TTG TCT TGA C R – GGC GAT GAC CTA CTT TCG P – 56-FAM/CGA ACT CAG/ZEN/AAG TGA AAC/3IABkFQ	(Herpers et al. 2003)
Legionella pneumophila	F – GCA TTG GTG CCG ATT TGG R – GYT TTG CCA TCA AAT CTT TCT GAA P – 56-FAM/CCA CTC ATA/ZEN/GCG TCT TGC ATG CCT TTA/3IABkFQ	(Joly et al. 2006)
Legionella longbeachae	F – AGA TGG GAT GTC TGG TGC TC R – ACC TGG TTT TGC ACC AGT TC P – 56-FAM/ACA AAG CAA/ZEN AAG GTG ACG CT/3IABkFQ	(Hamilton et al. 2016)
Staphylococcus aureus	F – GCG ATT GAT GGT GAT ACK GT R – AGC CAA GCC TTG ACG AAC TAA	(Lu, Wang, and Zhang 2012)
Methicillin-resistant S. aureus (MRSA)	F – GGA TCA AAC GGC CTG CAC A R – GTC AAA AAT CAT GAA CCT CAT TAC TTA TG P – 56-FAM/CGT AGT TAC/ZEN/TGC GTT GTA AGA CGT C/3IABkFQ	(Huletsky et al. 2004)
Salmonella sp.	F – CGT TTC CTG CGG TAC TGT TAA TT R – AGA CGG CTG GTA CTG ATC GAT AA P – 56-FAM/CCA CGC TCT/ZEN/TTC GTC T/3IABkFQ	(Shannon et al. 2007)
Streptococcus agalactiae	F – TTT GGT GTT TAC ACT AGA CTG R – TGT GTT AAT TAC TCT TAT GCG	(de Carvalho et al. 2015)
Saccharopolyspora rectivirgula	F – TGT GGT GGG GTG GAT GAG T R – ACC ATG CGG CAG AAT GTC CT	(Schafer, Kampfer, and Jackel 2011)
Penicillium/Aspergillus	F – CGG AAG GAT CAT TAC TGA GTG R – GCC CGC CGA AGC AAC P – 56-FAM/CCA ACC TCC/ZEN/CAC CCG TG/3IABkFQ	(Haugland et al. 2004)
Aspergillus fumigatus	F – GCC CGC CGT TTC GAC R – CCG TTG TTG AAA GTT TTA ACT GAT TAC P – 56-FAM/CCC GCC GAA/ZEN/GAC CCC AAC ATG/3IABkFQ	(Haugland et al. 2004)

Notes. ¹ W = A/T, S = C/G, K = G/T, R = A/G and Y = C/T

Table 2. Airborne dust, total bacteria, Penicillium/Aspergillus, and endotoxin concentrations in chambers containing RMS composted by static windrow (SW), daily turned windrow (TW), static windrow following 24 h in a rotating composting drum (DC24) or by static windrow following 72 h in a rotating composting drum (DC72)

Aging in piles (days)	Composting methods	Air quality indicators (average values)
		PM1 (mg/m^3)	PM2.5 (mg/m^3)	PM10 (mg/m^3)	Total dust (mg/m^3)	Total bacteria (E. coli eq/m^3)	Penicillium/Aspergillus (A. fumigatus eq/m^3)	Endotoxins (EU/m^3)
0 day (filling of the pipes)	SW	0.03 ^a	0.03 ^a	0.04 ^a	0.06 ^a	9.5 × 10^6 a	5.7 × 10^2 a	315.8
	TW	0.03 ^a	0.03 ^a	0.04 ^a	0.06 ^a	1.1 × 10^7 a	9.6 × 10^2 ab	347.9
	DC24	0.02 ^b*	0.02 ^b	0.04 ^a	0.06 ^a	3.4 × 10^7 b	3.9 × 10^2 bc	1,227.9
	DC72	0.07 ^c	0.07 ^c	0.11 ^b	0.14 ^b	4.0 × 10^7 b	3.8 × 10^3 c	279.2
5 days (static piles)	SW	0.03 ^a	0.03 ^a	0.03 ^a	0.03 ^a	< 4.2 × 10^3 a	< 8.3 × 10^1 a	0.4
	TW ^†	0.03 ^a	0.03 ^a	0.03 ^a	0.03 ^a	< 4.2 × 10^3 a	< 8.3 × 10^1 ab	<0.1
	DC24	0.01 ^b	0.01 ^b	0.01 ^b	0.01 ^b	2.6 × 10^5 b	3.1 × 10^2 bc	1.0
	DC72	0.01 ^b	0.01 ^b	0.01 ^b	0.02 ^b	1.4 × 10^6 b	9.2 × 10^1 c	0.3
10 days (static piles)	SW	0.01 ^a	0.01 ^a	0.01 ^a	0.01 ^a	3.6 × 10^5 a	< 8.3 × 10^1 a	1.6
	TW	0.01 ^a	0.01 ^a	0.01 ^ab	0.01 ^a	1.2 × 10^6 a	1.1 × 10^2 a	7.4
	DC24	0.02 ^b	0.02 ^b	0.03 ^bc	0.04 ^ab	2.6 × 10^6 b	3.5 × 10^2 bc	17.1
	DC72	0.06 ^c	0.06 ^b	0.06 ^c	0.06 ^b	3.3 × 10^5 c	2.1 × 10^2 c	2.1

Notes. ^a-c Within a day and an air quality indicator, a different lowercase superscript letter reveals a significant difference (P < .05) as exemplified for PM1 values on day 0 (numerical values in the black square).

* The lowest concentrations within a day and an air quality indicator are emphasized in bold characters.

^†Air samples were taken before the turnover of the TW piles.

Table 3. Airborne dust, total bacteria, Penicillium/Aspergillus, and endotoxin concentrations in chambers containing RMS composted by daily turned windrow

Aging in piles (days)	Turned windrow	Air quality indicators (average values)
		PM1 (mg/m^3)	PM2.5 (mg/m^3)	PM10 (mg/m^3)	Total dust (mg/m^3)	Total bacteria (E. coli eq/m^3)	Penicillium/Aspergillus (A. fumigatus eq/m^3)	Endotoxins (EU/m^3)
5 days	Before turning	0.03	0.03	0.03	0.03	< 4.2 × 10^3	< 8.3 × 10^1	<0.1
	During turning	0.03	0.03	0.04	0.05	1.1 × 10^7 ^a	2.2 × 10^2 ^a	571.8 ^a
10 days	Before turning	0.01	0.01	0.01	0.01	1.2 × 10^6	1.1 × 10^2	7.4
	During turning	0.02 ^a	0.03 ^a	0.05 ^a	0.07 ^a	2.8 × 10^7 ^a	6.7 × 10^2 ^a	341.8 ^a

Notes. ^a Within a day and an air quality indicator, concentration during turnover is significantly higher than the one before the mechanical disturbance of the pile (P <.05) as exemplified for PM10 values on day 10 (numerical values in the black square).

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