Achieving water authority compliance with marina wastewater treatment

Wastewater treatment systems help marinas remain in compliance with EPA and local standards, while significantly reducing the cost of treatment, labour and disposal. Recreational and military marinas must meet EPA and local wastewater requirements for effluent, including those under the Clean Water Act.  Failing to do so can result in severe fines that quickly escalate.

Whether for yachts or cutters, one source of considerable wastewater involves the use of anti-fouling paint on the underwater part of ships’ hulls.  Anti-fouling paint is applied to slow the growth and/or facilitate detachment of subaquatic organisms, such as barnacles, from the hull that can affect a vessel’s performance and durability.  It can also act as a barrier against corrosion on metal hulls.

However, because anti-fouling paint typically consists of lead, zinc, and copper, when ships are drydocked and pressure washed in a marina, this results in a wastewater stream that must be dealt with to stay in compliance with regulatory standards.  Bilge water, which can contain oil and other contaminants, is another common source of wastewater.

Under the Clean Water Act alone, the EPA has identified 65 pollutants and classes of pollutants as “toxic pollutants”, of which 126 specific substances have been designated “priority” toxic pollutants.

For many marinas, this means installing a wastewater treatment system that effectively separate the contaminants from the water so it can be legally discharged.

However, traditional wastewater treatment systems can be complex, often requiring multiple steps, a variety of chemicals and a considerable amount of labour.  Even when the process is supposedly automated, too often technicians must still monitor the equipment in person.  This usually requires oversight of mixing and separation, adding of chemicals, and other tasks required to keep the process moving.  Even then, the water produced can still fall below mandated requirements.

Although paying to have such wastewater hauled away is also an option, it is expensive.  In contrast, it is much more cost effective to treat the wastewater at its source, so treated effluent can be legally discharged and treated sludge passes a TCLP (Toxicity Characteristics Leaching Procedure) test and can be disposed of as non-hazardous waste in a local landfill.

Fortunately, complying with EPA and local wastewater regulation has become much easier with a variety of more fully automated wastewater treatment systems.  Such systems not only reliably meet regulatory wastewater requirements, but also significantly reduce the cost of treatment, labour and disposal when the proper Cleartreat® separating agents are also used.

Cost-effective, automated wastewater treatment
In contrast to labour-intensive multiple step processes, automated wastewater treatment can help to streamline production, usually with a one-step process, while lowering costs at marinas.

An automated wastewater treatment system can eliminate the need to monitor equipment in person while complying with EPA and locally mandated requirements.  Such automated systems separate suspended solids, emulsified oil and heavy metals, and encapsulate the contaminants, producing an easily de-waterable sludge in minutes.  The water is typically separated using a de-watering table or bag filters before it is legally discharged.  Other options for de-watering include using a filter press or rotary drum vacuum.  The resulting solids are non-leachable and are considered non-hazardous, so will pass all required testing.

These systems are available as manual batch processors, semi-automatic, automatic and can provide a legally dischargeable effluent.  A new, fully customised system is not always required.  In many cases, it can be faster and more cost effective to add to or modify a marina’s current wastewater treatment systems when this is feasible.

However, because every wastewater stream is unique to its application, each wastewater treatment solution must be suited to or specifically tailored to the application.  The first step in evaluating the potential cost savings and effectiveness of a new system is to sample the wastewater to determine its chemical make-up followed by a full review of local water authority requirements.  The volume of wastewater that will be treated is also analysed, to determine if a batch unit or flow-through system is required.  Other considerations include the size restrictions so the system fits within the marina’s available footprint.

An example of successful semi-automated wastewater treatment involves Mystic Shipyard, a marina in Mystic, Connecticut.

When boats are removed from the water at the marina to remove bottom growth such as barnacles and algae, the pressure washing process also removes anti-fouling paint.  Most anti-fouling paints contain metals and biocides that are released into the wash water, creating a waste stream that may contain lead, zinc, and copper and suspended solids.

To treat this waste stream, Mystic Shipyard turned to a 250-gallon batch tank, bag filter tank, and Cleartreat separating agent from Sabo Industrial Corp., a New York-based manufacturer, distributor and integrator of industrial waste treatment equipment and solutions, including batch and fully automated systems, separating agents, bag filters, and accessories.

The wastewater is pumped to the 250-gallon mix tank, where a float disengages the catch basin sump pump to prevent overflow.  10 lbs of the separating agent are added at a 0.5% introduction rate to create large sturdy floc.  The treated effluent is then transferred to the bag filter tank for sludge filtering.  The tank’s four independently operated bag manifolds enable continuous use and maximum dewatering.

The sludge produced is captured in the bag filters and is easily disposed of in a local municipal landfill.  The sludge will not break down and will not return the contaminants to the water supply.  The treated effluent is collected in the tank for legal discharge to the sewer system or is suitable for reuse.

According to Jeff Marshall, President of Mystic Shipyard, the SABO RT250 Cleartreat clay system was the right choice for many reasons, including reliability and ease of operation.  Most important, he says that it produces an end result which is well below the DEP’s and sewer authority requirement for discharge to the sewer.  By not having to haul the wastewater away, he adds that this year he was able to pay for over half of the initial investment.

Separating Agents
Despite all the advances in automating wastewater treatment equipment any such system requires effective separating agents which agglomerate with the solids in the wastewater so the solids can be safely and effectively separated out.

Because of the importance of separating agents for wastewater treatment, Sabo Industrial uses a special type of bentonite clay in a line of wastewater treatment chemicals called ClearTreat.  This line of wastewater treatment chemicals is formulated to break oil and water emulsion, provide heavy metals removal, and promote flocculation, agglomeration and suspended solids removal.

Bentonite has a large specific surface area with a net negative charge that makes it a particularly effective adsorbent and ion exchange for wastewater treatment applications to remove heavy metals, organic pollutants, nutrients, etc.  It has the ability to swell 16 times its normal weight when introduced and mixed with wastewater.  As such, bentonite is essential to effectively encapsulate the materials.  This can usually be achieved in one-step treatment, which lowers process and disposal costs.

In contrast, polymer-based products do not encapsulate the toxins, so systems that use that type of separating agent are more prone to having waste products leach back out over time or upon further agitation, which can result in compliance violations.

As a point of comparison, if treated polymer floc is shaken in a container, it will go right back into a wastewater solution.  However, Cleartreat floc, if shaken in a container will remain separated as floc and crystal-clear water.

After using separating agents, typically a valve is opened and the treated effluent or floc-ed waste stream is pumped through a bag filter, de-watering table, rotary drum vacuum, or other type of filtration.  The floc or sludge stays in the bag and the clear water passes through.

When the bag finishes de- watering, the pumps are usually left on because bentonite is hydrophobic, which means that it continues to shed water when removed from water.  So, over time it will become extremely hard and pass any TCLP test.  In fact, copper lead, and zinc become virtually undetectable in the treated wastewater and encapsulated sludge.

A maritime fleet is now utilising such an approach to treat wastewater stemming from its use of anti-fouling paint when its vessels are drydocked and pressure washed semi-annually for maintenance.

A similar wastewater treatment approach is also being considered to treat bilge water.

Traditionally bilge water is vacuumed from boats and stored in barrels, which are hauled away at a cost of nearly $2.00 (S$2.78) a gallon. Instead, wastewater treatment can be utilised in a marina at an estimated cost of about $0.30 (S$0.42) a gallon.

Today’s advanced more automated wastewater treatment systems, along with the most effective Cleartreat separating agents, can provide marinas with an easy, economical alternative so they remain compliant with local ordinances and the EPA. Although there is a cost to these systems, they do not require much attention and can easily be more affordable than paying fines or hauling.