An environmentally friendly and cost-effective solution to the disposal of oily sludge waste has been developed by engineers, microbiologists, and chemists from Naval Facilities Engineering Command Hawaii (NAVFAC) Hawaii and NAVFAC Engineering Service Center (ESC).
The solution makes it possible to remediate oily sludge waste at Pearl Harbor instead of shipping it to the mainland for disposal, which is a large cost burden and liability for the Navy. Remediating the waste is also a sustainable practice. Natural elements and processes are used, and the by-products of the remediation are natural and harmless to the environment.
The oily sludge waste remediation project began as a pilot study in 2004 at the Bilge Water/Oily Waste Treatment Facility at Pearl Harbor. After achieving successful results of similar biological remediation efforts at the NAVFAC Biosolids Facility at Kalaeloa (formerly Barbers Point), Christiansen and his colleagues at NAVFAC Hawaii started work on a biological reactor they hoped would specifically remediate oily sludge waste. Chemists and microbiologists from NAVFAC ESC in Port Hueneme, Calif., who have worked closely with NAVFAC Hawaii on other projects, were asked to assist.
A prototype reactor was built at a minimal cost. The initial plant was assembled from old components, and excess tanks found around Pearl Harbor. It took less than a year for the reactor to be assembled and successfully tested. However, technical challenges caused some delays.
"Initial test results were not promising," said Vernon Kam, a NAVFAC chemist who worked on the project and is now responsible for day-to-day operation of the treatment system. "But modifications of the process that included control of foaming, more thorough mixing, and the addition of nutrients that supported a more robust bacterial population, demonstrated the potential of on-site bacterial remediation."
After achieving the desired results, test data and process modifications were presented to the command's Environmental Compliance Group for review. Upon their recommendations, upgrades were made to the facility, and in late 2007, full-scale testing began. Additional upgrades were made to the facility as it continued to process material during 2008. The Oily Waste Treatment Facility is currently ready for full production.
The oily sludge waste remediation process is similar to the one used to remediate sewage sludge. Oily waste is mixed with water, nutrients, and oxygen. The mixture activates bacteria which are already present and rapidly remodel the waste's hydrocarbons into basic molecules found in all living organisms. During this process, the bacteria extracts energy needed for life processes. In return for providing the bacteria with a food and an energy source, they convert the oily sludge into harmless end products.
"The whole idea behind this effort is to maximize bacteria activity and minimize processing time," said Dr. Frederick Goetz, a microbiologist working for NAVFAC ESC. "In order to do that, we need to keep the bacteria healthy feeding them oxygen, vitamins, nutrients, and amino acids."
In the beginning the process took 10 days, but as the bacteria acclimated and became more effective, that time was reduced to four days.
"The bacteria break down the hydrocarbons found in oily sludge waste, converting them into carbon dioxide, water and biomass or more bacteria," said Kam. "The remediation process is so complete that after testing, the resultant water can be discharged into the Navy's wastewater collection system and processed at our sewage plant."
At the end of a treatment cycle, the treated water is passed through a filter that captures bacteria and solids which are sent back to the reactor and mixed with the next batch of oily waste. The excess biomass that accumulates in the treatment system is periodically harvested and sent to the Biosolids Remediation Facility at Barbers Point.
Currently the Oily Waste Remediation Facility at Pearl Harbor is able to treat 10,000 gallons of the oily waste and water mixture at a time. The facility is expanding and plans on raising treatment capacity to 20,000 gallons by the end of fiscal year 2009. The two biggest users of the new process are the Fleet Industrial Supply Center at Pearl Harbor and the Pearl Harbor Naval Shipyard.
In the past, the Navy shipped its oily waste from Hawaii to regulated landfills on the mainland. This expensive process required the Navy to pay for shipping and storage. Additionally, after the oily waste is stored at the landfill, the Navy remains responsible and liable for it and any environmental damage it may cause in perpetuity. By remediating the oily waste on-site through natural processes instead of shipping it to disposal facilities, the Navy saves money and reduces its liabilities.
"Treatment costs at NAVFAC Hawaii are comparable to what a contractor would charge," said Christiansen. "But we save money by avoiding shipping costs and permitting fees. Plus, our method is far more environmentally friendly."
(Source: Navy News Service)