acknowledged most of these damaging effects, and remedial
actions to protect the environment are more than a necessity
today. Therefore, to maintain a sustainable industrial and
economic development, there is a need to be fulfilled in terms
of the expansion and optimization of alternative technologies
or processes. This will allow a productive and sustainable
farming as well as a cost-effective agriculture, while at the
same time minimizing the negative effects on the environment. Also, it is important to mention that treatment of
manure effluents can improve farm profitability (Joshi and
Wang 2018; Dennehy et al. 2017). By processing manure
effluents there is an option to decrease ammonia emission
(Chadwick et al. 2020; García-González et al. 2019). Treatment of manure provides many benefits and the payback time
is short (Hanifzadeh et al. 2017; Thu et al. 2012). Some of the
key benefits amongst many are reduced ammonia emission as
mentioned before, less storage capacity requirement and more
efficient transports. There is an extensive diversity of farms for
which the differences are based on environmental challenges
and resources. There are number of farms with more advantages than other. These advantages include easy access to
finances, skilled human resources, effective managing
capacity, water and land assets (Altieri 2002). The farm
position and management are directly linked to environmental
challenges for any farming operation (Altieri 2002).
It is important to stress on the fact that larger farming
operations generate bigger quantities of manure and higher
amounts of nutrients at any site.
Consequently, the possibilities of point source pollution
are also increased (Miner and Moore 2000). Studies should
be undertaken with the aim to develop, validate and optimize
technologies with the ability to decrease the volumes of
manure and concentrate the nutrients through improved
water management within the farming operations. Therefore,
the following should be required: more effective use of
feedstuff resources by the animals within a farming environment, effective separation of phases for the manure
effluent to get both liquid and solid phases separately and
undertaking cost-effective manure aeration.
Manure effluents may contain non-soluble and gradually
biodegradable suspended solids. The increase of suspended
particles can decrease light diffusion into a water body
(Busato et al. 2020; USEPA 2002; Timmerman and Hoving
2016). They also contain phosphorus (P) and nitrogen
(N) nutrients which are the main sources of eutrophication in
surface waters (Busato et al. 2020; Murry et al. 2019). As a
result, the dissolved oxygen content is reduced in water
bodies to those levels that are insufficient for aquatic life.
This could cause a rise of the destructive effects of algal
blooms that are discharging contaminants while dying and
harshly affecting wildlife and human beings. Besides,
ammonia (NH 3 ) is a known toxic substance to marine life
from the fast biodegradation of organic nitrogen (N 2 ) in
wastewater (USEPA 2002; Amenu 2014). Pathogens in
manure effluents can impact negatively on various freshwater resources; this includes potable water and marine life
(USEPA 2002; Nemerow et al. 2009). Consequently,
appropriate disposal of manure effluent is vital for public
protection and prevention of water contamination including
the preservation of aquatic life and wildlife (Ebner 2017;
Goss and Richards 2008; Takahashi et al. 2020). Bioremediation and bioconversion of manure effluents may be
specific to each country depending on various aspects linked
to environmental and manure type (Murry et al. 2019;
El-Sheekh et al. 2016). There are many options that can be
undertaken by the farming industry for successful bioremediation of manure effluents. Various methods depend on
local environmental conditions, the nature and type of
manure effluents and requirements for effluent discharge
(Murry et al. 2019; Vanotti et al. 2020; Liu and Wang 2020).
Effluents from farming and agricultural industries are treated
by similar processes and operations compared to the ones
used in a conventional wastewater treatment plant. Additional treatment steps are undertaken depending on the origin, nature and content or quality of the generated effluents
(USEPA 2002). Bioconversion processes of manure effluents can be undertaken in bioreactors. Their operational
mode can be achieved in batch, continuous or semicontinuous. Additionally, various configurations of bioreactors are used depending on the feedstock nature. The
technology deals with the conversion of solid to a gas phase
as well as aqueous phase bioprocesses. Bioconversion processes of manure are known to be environmentally friendly
alternatives. A range of cost-effective by-products is generated using affordable biocatalysts under achievable operating
conditions. More studies are still needed for the optimization
of emerging bioconversion processes. This chapter focuses
on various treatments and bioconversion technologies for
manure effluents to preserve the close environment from any
negative effects due their handling or discharge.
2 Manure Handling Processes
2.1 Physical Treatments
There are many alternatives for manure effluent management; before the conversion process which can be chemical
or biological, physical treatment processes can be undertaken for the separation of solid and liquid fractions, handling or conditioning. This section presents some of them in
terms of their advantages and disadvantages.
300
J. K. Bwapwa
actions to protect the environment are more than a necessity
today. Therefore, to maintain a sustainable industrial and
economic development, there is a need to be fulfilled in terms
of the expansion and optimization of alternative technologies
or processes. This will allow a productive and sustainable
farming as well as a cost-effective agriculture, while at the
same time minimizing the negative effects on the environment. Also, it is important to mention that treatment of
manure effluents can improve farm profitability (Joshi and
Wang 2018; Dennehy et al. 2017). By processing manure
effluents there is an option to decrease ammonia emission
(Chadwick et al. 2020; García-González et al. 2019). Treatment of manure provides many benefits and the payback time
is short (Hanifzadeh et al. 2017; Thu et al. 2012). Some of the
key benefits amongst many are reduced ammonia emission as
mentioned before, less storage capacity requirement and more
efficient transports. There is an extensive diversity of farms for
which the differences are based on environmental challenges
and resources. There are number of farms with more advantages than other. These advantages include easy access to
finances, skilled human resources, effective managing
capacity, water and land assets (Altieri 2002). The farm
position and management are directly linked to environmental
challenges for any farming operation (Altieri 2002).
It is important to stress on the fact that larger farming
operations generate bigger quantities of manure and higher
amounts of nutrients at any site.
Consequently, the possibilities of point source pollution
are also increased (Miner and Moore 2000). Studies should
be undertaken with the aim to develop, validate and optimize
technologies with the ability to decrease the volumes of
manure and concentrate the nutrients through improved
water management within the farming operations. Therefore,
the following should be required: more effective use of
feedstuff resources by the animals within a farming environment, effective separation of phases for the manure
effluent to get both liquid and solid phases separately and
undertaking cost-effective manure aeration.
Manure effluents may contain non-soluble and gradually
biodegradable suspended solids. The increase of suspended
particles can decrease light diffusion into a water body
(Busato et al. 2020; USEPA 2002; Timmerman and Hoving
2016). They also contain phosphorus (P) and nitrogen
(N) nutrients which are the main sources of eutrophication in
surface waters (Busato et al. 2020; Murry et al. 2019). As a
result, the dissolved oxygen content is reduced in water
bodies to those levels that are insufficient for aquatic life.
This could cause a rise of the destructive effects of algal
blooms that are discharging contaminants while dying and
harshly affecting wildlife and human beings. Besides,
ammonia (NH 3 ) is a known toxic substance to marine life
from the fast biodegradation of organic nitrogen (N 2 ) in
wastewater (USEPA 2002; Amenu 2014). Pathogens in
manure effluents can impact negatively on various freshwater resources; this includes potable water and marine life
(USEPA 2002; Nemerow et al. 2009). Consequently,
appropriate disposal of manure effluent is vital for public
protection and prevention of water contamination including
the preservation of aquatic life and wildlife (Ebner 2017;
Goss and Richards 2008; Takahashi et al. 2020). Bioremediation and bioconversion of manure effluents may be
specific to each country depending on various aspects linked
to environmental and manure type (Murry et al. 2019;
El-Sheekh et al. 2016). There are many options that can be
undertaken by the farming industry for successful bioremediation of manure effluents. Various methods depend on
local environmental conditions, the nature and type of
manure effluents and requirements for effluent discharge
(Murry et al. 2019; Vanotti et al. 2020; Liu and Wang 2020).
Effluents from farming and agricultural industries are treated
by similar processes and operations compared to the ones
used in a conventional wastewater treatment plant. Additional treatment steps are undertaken depending on the origin, nature and content or quality of the generated effluents
(USEPA 2002). Bioconversion processes of manure effluents can be undertaken in bioreactors. Their operational
mode can be achieved in batch, continuous or semicontinuous. Additionally, various configurations of bioreactors are used depending on the feedstock nature. The
technology deals with the conversion of solid to a gas phase
as well as aqueous phase bioprocesses. Bioconversion processes of manure are known to be environmentally friendly
alternatives. A range of cost-effective by-products is generated using affordable biocatalysts under achievable operating
conditions. More studies are still needed for the optimization
of emerging bioconversion processes. This chapter focuses
on various treatments and bioconversion technologies for
manure effluents to preserve the close environment from any
negative effects due their handling or discharge.
2 Manure Handling Processes
2.1 Physical Treatments
There are many alternatives for manure effluent management; before the conversion process which can be chemical
or biological, physical treatment processes can be undertaken for the separation of solid and liquid fractions, handling or conditioning. This section presents some of them in
terms of their advantages and disadvantages.
300
J. K. Bwapwa