Energy potential of biogas and sludge from UASB reactors in the state of Paraná, Brazil

Lopes, Lucas Sampaio; Rosa, Andre Pereira; Marco, Júlia Silva; Possetti, Gustavo Rafael Collere; Mesquita, Tayane Cristiele Rodrigues

doi:10.4136/ambi-agua.2398

Lucas Sampaio Lopes

Departamento de Engenharia Agrícola. Universidade Federal de Viçosa (UFV), Avenida Peter Henry Rolfs, s/n, CEP: 36570-900, Viçosa, MG, Brazil. E-mail: lucasctu@gmail.com, andrerosa@ufv.br, tayanemesquita@yahoo.com.br

https://orcid.org/0000-0001-8167-6990

Andre Pereira Rosa ^**Corresponding author: Andre Pereira Rosa, e-mail: andrerosa@ufv.br

Departamento de Engenharia Agrícola. Universidade Federal de Viçosa (UFV), Avenida Peter Henry Rolfs, s/n, CEP: 36570-900, Viçosa, MG, Brazil. E-mail: lucasctu@gmail.com, andrerosa@ufv.br, tayanemesquita@yahoo.com.br

https://orcid.org/0000-0001-5490-5698

Júlia Silva Marco

Departamento de Geografia. Universidade Federal de Viçosa (UFV), Avenida Peter Henry Rolfs, s/n, CEP: 36570-900, Viçosa, MG, Brazil. E-mail: juliasmarco18@gmail.com

https://orcid.org/0000-0002-2805-3863

Gustavo Rafael Collere Possetti

Gerência de Pesquisa e Inovação. Companhia de Saneamento do Paraná (Sanepar), Rua Engenheiro Antônio Batista Ribas, n° 151, CEP: 82800-130, Curitiba, PR, Brazil. E-mail: grcpossetti@gmail.com

Programa de Mestrado Profissional em Governança e Sustentabilidade. Instituto Superior de Administração e Economia do Mercosul (ISAE), Avenida Visconde de Guarapuava, n° 2943, CEP: 80010-100, Curitiba, PR, Brazil. E-mail: grcpossetti@gmail.com

https://orcid.org/0000-0001-8816-5632

Tayane Cristiele Rodrigues Mesquita

Departamento de Engenharia Agrícola. Universidade Federal de Viçosa (UFV), Avenida Peter Henry Rolfs, s/n, CEP: 36570-900, Viçosa, MG, Brazil. E-mail: lucasctu@gmail.com, andrerosa@ufv.br, tayanemesquita@yahoo.com.br

https://orcid.org/0000-0003-0324-5049

*Corresponding author: Andre Pereira Rosa, e-mail: andrerosa@ufv.br

	Parameter	Unit	Scenario
	Parameter	Unit	Worst	Typical	Best
Biogas	Population equivalent (Pop)	inhab.	1,000 - 1,000.000
	Contribution per capita of sewage (PSC)	m³ inhab^-1 d^-1	0.12 - 0.22
	Contribution per capita of COD (QPC_COD)	m³ inhab^-1 d^-1	0.09 - 0.11
	Removal efficiency of COD (E_COD)	%	60	65	70
	Sulphur concentration in sewage (CSO₄)	kgSO₄ m^-3	0.08	0.06	0.04
	Sulphur efficiency reduction (ESO₄)	%	80	75	70
	Operational temperature in the reactor (T)	°C	20 - 30
	Percentage of CH₄ in the biogas (CCH₄)	%	70	75	80
	COD_CH4 lost as waste gas (p_W)	%	75	5.0	2.5
	Other COD_CH4 losses (p_o)	%	75	5.0	2.5
	Dissolved COD_CH4 lost with the effluent (p_L)	kg m^-3	0.025	0.020	0.015
Sludge	Inside the UASB reactor
	Sludge density (ρs)	kg m^-3	1,020 - 1,030
	Solids concentration (C)	%	3 - 6
	Sludge yield (Y_ss)	kgSS kgCOD_app ^-1	0.18
	Dehydrated sludge
	Solids capture - Centrifuge (Sc)	%	90 - 91	92 - 93	94 - 95
	Solids capture - Drying bed (Sc)	%	90 - 92	93 - 95	96 - 98
	Solids concentration - Centrifuge (C')	%	18 - 21	22 - 24	25 - 27
	Solids concentration - Drying bed (C')	%	30 - 34	35 - 39	40 - 44
	Sludge density (ρs')	kg m^-3	1,050 - 1,080
	Carbon (C)¹	%	18	30	38
	Hydrogen (H)¹	%	3.6	4.4	6.1
	Nitrogen (N)¹	%	1.6	1.9	2.5
	Sulphur (S)¹	%	0.8	1.2	1.4
	Oxygen (O)¹	%	21	22	24
	Ashes¹ (A)¹	%	55	40.5	28

Parcels	Equations	Notes
Estimate of mean influent flow rate	$F_{m e a n} = P o p \times P S C$	F_{mean =} Mean influent flow rate (m³ d^-1) Pop = population (inhab.) PSC = per-capita sewage contribution (m³ inhab^-1 d^-1)
Estimate of daily COD mass removed from the system	$C O D_{r e m o v} = P o p \times P S C \times {C O D}_{i n f}$ ${C O D}_{r e m o v} = F_{m e a n} \times {C O D}_{i n f} \times E_{C O D}$	COD_remov = daily COD mass removed from the system (kgCOD d^-1) COD_inf = COD concentration influent (kgCOD m^-3) E_COD = efficiency of COD removal (%) F_mean = mean influent flow rate (m³ d^-1)
Estimate of daily COD mass used by the biomass	$C O D_{s l u d g e} = C O D_{r e m o v} \times Y_{C O D}$ $Y_{C O D} = Y T V S \times K_{T V S - C O D}$	COD_sludge = daily COD mass converted into biomass (kgCOD_sludge d^-1) Y_COD = sludge yield, as COD (kgCOD_sludge kgCOD_rem ^-1) Y_TVS = sludge yield, as total volatile solids (TVS) (kgTVS kgCOD_rem ^-1) K_TVS-COD = conversion factor (1kgTVS = 1.42 kgCOD_sludge)
Estimate of sulfate load converted into sulfide	$C {O_{S O}}_{4}_{c o n v e r t e d} = F_{m e a n} \times C_{S O_{4}} \times E_{S O_{4}}$	CO_SO4converted = load of SO₄ converted into sulfide (kgSO₄ d^-1) C_SO4 = average influent SO₄ concentration (kgSO₄ m^-3) E_SO4 = efficiency of sulfate reduction (%)
Estimate of daily COD mass used in sulfate reduction	$C O D_{S O_{4}} = C {O_{S O}}_{4}_{c o n v e r t e d} \times K_{C O D - S O_{4}}$	COD _SO4= COD used by the sulfatereducingbacteria for sulfate reduction (kgCOD_SO4 d^-1) K_COD-SO4 = COD consumed in sulfate reduction (0.667 kgCOD_SO4 kgSO₄ ^-2)
Estimate of daily COD mass converted into methane	$C O D_{C H_{4}} = C O D_{r e m o v} - C O D_{s l u d g e} - C O D_{S O_{4}}$ $Q_{C H_{4}} = \frac{C O D_{C H_{4}} \times R \times (273 + T)}{P \times K_{C O D} \times 1,000}$	COD_CH4 = daily COD mass converted into methane (kgCOD_CH4 d^-1) Q_CH4 = theoretical volumetric production of methane (m³ d^-1) R = gas constant (0.08206 atm L mol^-1 K^-1) T = operational temperature of the reactor (^oC) P = atmospheric pressure (1 atm) K_COD = COD of one mole of CH₄ (0.064 kgCOD_CH4 mol^-1)
Estimate of methane loss	$Q_{O - C H_{4}} = Q_{C H_{4}} \times p_{O}$ $Q_{W - C H_{4}} = Q_{C H_{4}} \times p_{w}$ $Q_{L - C H_{4}} = F m e a n \times p_{L} \times f_{C H_{4}} (\frac{R \times (273 + T)}{P \times K_{C O D}})$ $p_{L} = \frac{% C H_{4}}{100} \times k_{h} \times F_{s}$	Q_W-CH4 = methane loss as waste gas (m³ d^-1) p_w = percentage of methane in the gaseous phase lost as waste gas (%) Q_O-CH4 = other methane losses in the gaseous phase (m³ d^-1) p_O = percentage of methane in the gaseous phase considered as other losses (%) Q_L-CH4 = loss of dissolved methane in the liquid effluent (m³ d^-1) p_L = concentration of dissolved methane in the liquid effluent (kg m^-3) f _CH4 = conversion factor of methane mass into COD mass (4 kgCOD kgCH₄ ^-1) K_h = constant of Henry (mg.L^-1 atm^-1) F_s = supersaturation factor of CH₄ in the liquid phase % CH₄ = percentage of CH₄ in the biogas
Estimate of actual methane production	$Q_{a c t u a l - C H_{4}} = Q_{C H_{4}} - Q_{W - C H_{4}} - Q_{O - C H_{4}} - Q_{L - C H_{4}}$	Q_actual-CH4 = actual production of methane available for energy recovery (m³ d^-1)
Energy recovery potential	$P E_{a c t u a l - C H_{4}} = Q_{N - a c t u a l - C H_{4}} \times E_{C H_{4}}$	PE_actual-CH4 = energy potential of biogas (MJ d^-1) Q_N-actual-CH ₄ = normalized methane production (Nm³ d^-1) E_CH4 = calorific energy of methane (35.9 MJ Nm^-3)

Parcels	Equations	Notes
UASB reactor
Influent COD load	$C O D_{a p p} = P o p \times P C L_{C O D}$	COD_app = COD load applied to the system (kgCOD d^-1) Pop = population (inhab.) PCL_COD = per capita contribution of COD (kg.inhab^-1 d^-1)
Sludge production	$P_{s} = C O D_{a p p} \times Y_{s s}$	P_s = sludge production in the system (kg SS d^-1) Y_SS = sludge yield (0.18 kgSS kg CODapp^-1)
Volumetric sludge production	$V_{s} = \frac{P_{s}}{[\frac{C}{100}] \times ρ_{s}}$	V_s = volumetric sludge production (m³ d^-1) C = solids concentration in the sludge (%) ρ_s = sludge density (kg m^-3)
Dewatering processes
Dry sludge production	$P_{s}^{'} = \frac{S_{c}}{100} \times P_{s}$	P_s = sludge production in the dehydration unit (kgSS d^-1) S_c = solids capture in the dehydration unit (%)
Energy potential of sludge
Theoretical HCV	$H C V = \frac{[337,3 \times C + 1.418,9 \times (H - \frac{O}{8}) + 93,1 \times S + 23,3 \times N]}{1.000}$	HCV = higher calorific value, (MJ kg^-1), d.b. Elemental composition C; H; O; S; N = % of carbon, hydrogen, oxygen, sulfur, nitrogen in the material, d.b.
Theoretical LCV	$L C V = [(H C V - λ \times (r + 0,09 \times H)) (100 W_{t}) / 100]$ $r = \frac{W_{t}}{(100 - W_{t})}$	LCV = lower calorific value (MJ kg^-1), m.b. λ = latent heat of water (2,31 MJ kg^-1 in 25 ˚C); r = solids content and dehydrated sludge moisture ratio H_s = hydrogen content (%), d.b. W_t = solids content in the dehydrated sludge (%), m.b.
Sludge energy potential	$P E_{s l u d g e} = L C V \times P_{s}^{'}$	PE_sludge = energy potential of sludge (MJ d^-1)

By-product	System	Relation (x,y)	Scenario
			Worst		Typical		Best
			Equation	(R²)	Equation	(R²⁾	Equation	(R²)
Biogas	-	L s^-1 x MJ d^-1	$y = 129.46 x$	0.98	$y = 180.91 x$	0.73	$y = 244.09 x$	0.82
Sludge	DB	L s^-1 x MJ d^-1	$y = 4.96 x$	0.78	$y = 108.82 x$	0.88	$y = 186.23 x$	0.89
Sludge	C	L s^-1 x MJ d^-1	Not applicable		$y = 7,50 x$	0.84	$y = 21,25 x$	0.86

[1] *Corresponding author: Andre Pereira Rosa, e-mail: andrerosa@ufv.br

Location	Sanitation company	STP	Treatment system	Population served (inhab.)	Installed capacity (inhab.)¹	CEP (GJ d^-1)²	FEP (GJ d^-1)³
Minas Gerais	COPASA	Arrudas	Activated sludge	1,343,867	4,049,193	218	1,484
		Betim	UASB	266,495
		Ibirité	Activated sludge	115,604
		Vieira/ Montes Claros	UASB	326,931
São Paulo	SABESP	Barueri	Activated sludge	4,400,000	5,520,818	161	2,024
	SABESP	Franca	Activated sludge	4,100.000
	SEMAE	São José do Rio Preto	UASB	438,000
	AMBIENT	Ribeirão Preto	Activated sludge	620,000
Paraná	SANEPAR	Belém	Activated sludge	600,000	7,300,603	11	2,676
Paraná	SANEPAR	Ouro Verde	UASB	29,500	7,300,603	11	2,676

Brasil

Brasil

Energy potential of biogas and sludge from UASB reactors in the state of Paraná, Brazil

Potencial energético do biogás e lodo de reatores UASB no estado do Paraná, Brasil

Abstract