Biofilm-based treatment for produced water

Description

Produced water (PW) represents the largest volume waste stream generated in oil and gas production operations. PW has a complex composition, which includes various production chemical residuals and naturally occurring organic and inorganic chemicals that are recalcitrant and difficult to remove. PW treatment would make it possible to meet future stricter regulation, and achieve zero harmful discharge into the sea. Physico-chemical and bioremediation methods utilized for removal of these compounds have shown various operational problems, such as generation of toxic gases, phase transfer of pollutants, residual sludge production and the impossibility of destroying refractory compounds. An additional problem offshore is the footprint of most treatment systems are generally unacceptable for an oil production platform. PW treatment facilities on land using traditional biological treatment have been struggling with fluctuations in water quality parameters, which makes treatment results unstable.
The potential of Moving bed biofilm reactors (MBBRs) to treat PW from various oil production have been shown in previous research. It appears bacteria in biofilm are vastly more robust to toxicants and variable salinity and pH as well as more capable to degrade complex organic molecules. In Denmark, a large pilot plant is currently operating in connection with the oil terminal in Fredericia and a full-scale system will be built in the coming two year.
In a current research project in DHRTCs produced water management program, a 3-stage MBBR system using AnoxKaldnes™ K5 carriers (Figure 1) with attached bacteria adapted to high salinity is being refined for biodegradation of organic compounds present in offshore PW. Due to space constraints at offshore platforms, this MBBR is intended to be located on the seafloor taking advantage of the higher pressure and potentially utilizing the higher temperature of PW (~30-40°C) to achieve even faster reaction rates compared to known land based systems. The established biofilm-based reactors were tested with different operational changes such as temperature (10 °C and 40°C), hydraulic loads and salinity while testing PW from different offshore platforms. Consistently, MBBR is able to degrade organic molecules such as toxic and persistent chemicals (including yellow and red list compounds) by adapted bacteria that are effectively retained in the reactors by the biofilms. The removal of pollutants concurs with whole water toxicity reduction.

Period	17 Nov 2021
Event title	DHRTC Technology Conference 2021 : Oil and Gas R&D towards 2050 – supporting the energy transition
Event type	Conference
Conference number	5
Location	Kolding, DenmarkShow on map
Degree of Recognition	International