been widely chosen as the adsorbent material as it exhibits large surface area with
plentiful distributed micropores (Coca-Prados et al. 2013). For example, Yang et al.
(2012) combined the ceramic microfiltration with the powdered activated carbon
which had seen 96% of the total organic carbon and p-xylene was removed from the
oily wastewater. However, the presence of powdered activated carbon did not
contribute to the removal of oil emulsion.
11.6 Challenges and Future Directions
There are lots of opportunities in the recycling of oily wastewater to improve the raw
crude oil exploitation efficiency. Likewise, there are also opportunities for the selling
of the concentrated oil obtained from the oily wastewater treatment plant to the oil
recycle industries. Moreover, the recuperation of the valuable metals from the oily
wastewater, particularly from the petrochemical industries, will present a feasible
economic opportunity if it is realized. However, the transformation of these opportunities into reality has remained an entangled endeavor.
In the real industry, the oily industrial effluent generally contains various
suspended and dissolved components that are difficult to be removed or recovered
using the one-size-fits-all treatment methods. In addition, the continuous review of
the regulatory wastewater discharge standards with more stringent limits further
increases the challenges faced by the treatment plants. For instance, the Department
of Petroleum of China imposes strict standards on the oily wastewater recycle with
the maximum allowable discharge limit of only 2 mg/L (Zeng et al. 2007). As the
result, the endeavor towards achieving the ideal treatment for the recycle or reuse of
the treated oily wastewater continues to be a challenging task (Tir and MoulaiMostefa 2008; Zouboulis and Avranas 2000). Hence, the treatment plant should be
tailored based on the types and conditions of the effluents, as well as the local
wastewater discharge standards.
Moreover, studies on the removal or recovery of heavy metals in the oily
wastewater are critically lacking. The presence of these heavy metals can be a
major hurdle for the recycle and reuse of the oily wastewater. In fact, some industrial
oily wastewaters, particularly from the oil and gas refineries, contain various heavy
metals, such as chromium, mercury, nickel, cadmium, copper, zinc, silver, and lead
(Yavuz et al. 2010). The hazardous features of heavy metals could result in malicious
impact if being released into the environment without proper treatment. Therefore,
future research should also direct towards the removal or recovery of heavy metals in
the oily wastewater. Electrochemical oxidation appears to be a prevailing and
effective approach for the removal of heavy metals from oily wastewater. For
instance, electrochemical treatment using the boron-doped diamond stone and platinum anodes could considerately remove various kinds of heavy metals (dos Santos
et al. 2014). Electrocoagulation treatment is another effective method in removing
heavy metals from oily wastewater. However, this method suffers from high operational cost due to heavy electricity consumption. Therefore, there is also a need to
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M. H. D. Othman et al.
plentiful distributed micropores (Coca-Prados et al. 2013). For example, Yang et al.
(2012) combined the ceramic microfiltration with the powdered activated carbon
which had seen 96% of the total organic carbon and p-xylene was removed from the
oily wastewater. However, the presence of powdered activated carbon did not
contribute to the removal of oil emulsion.
11.6 Challenges and Future Directions
There are lots of opportunities in the recycling of oily wastewater to improve the raw
crude oil exploitation efficiency. Likewise, there are also opportunities for the selling
of the concentrated oil obtained from the oily wastewater treatment plant to the oil
recycle industries. Moreover, the recuperation of the valuable metals from the oily
wastewater, particularly from the petrochemical industries, will present a feasible
economic opportunity if it is realized. However, the transformation of these opportunities into reality has remained an entangled endeavor.
In the real industry, the oily industrial effluent generally contains various
suspended and dissolved components that are difficult to be removed or recovered
using the one-size-fits-all treatment methods. In addition, the continuous review of
the regulatory wastewater discharge standards with more stringent limits further
increases the challenges faced by the treatment plants. For instance, the Department
of Petroleum of China imposes strict standards on the oily wastewater recycle with
the maximum allowable discharge limit of only 2 mg/L (Zeng et al. 2007). As the
result, the endeavor towards achieving the ideal treatment for the recycle or reuse of
the treated oily wastewater continues to be a challenging task (Tir and MoulaiMostefa 2008; Zouboulis and Avranas 2000). Hence, the treatment plant should be
tailored based on the types and conditions of the effluents, as well as the local
wastewater discharge standards.
Moreover, studies on the removal or recovery of heavy metals in the oily
wastewater are critically lacking. The presence of these heavy metals can be a
major hurdle for the recycle and reuse of the oily wastewater. In fact, some industrial
oily wastewaters, particularly from the oil and gas refineries, contain various heavy
metals, such as chromium, mercury, nickel, cadmium, copper, zinc, silver, and lead
(Yavuz et al. 2010). The hazardous features of heavy metals could result in malicious
impact if being released into the environment without proper treatment. Therefore,
future research should also direct towards the removal or recovery of heavy metals in
the oily wastewater. Electrochemical oxidation appears to be a prevailing and
effective approach for the removal of heavy metals from oily wastewater. For
instance, electrochemical treatment using the boron-doped diamond stone and platinum anodes could considerately remove various kinds of heavy metals (dos Santos
et al. 2014). Electrocoagulation treatment is another effective method in removing
heavy metals from oily wastewater. However, this method suffers from high operational cost due to heavy electricity consumption. Therefore, there is also a need to
376
M. H. D. Othman et al.