Interview with Marina Expert for Flovac, Francisco Rodríguez

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Francisco Rodríguez

At the end of 2017, aguasresiduales.info, Spain’s leading journal on wastewater and sanitation interviewed Flovac Spain’s Technical Director to understand the massive growth in the vacuum sewerage industry in Spain and elsewhere, particularly for Marina and Port infrastructure.

This is a translation from the original article which can be found here.

We speak with Francisco Rodríguez, Technical Manager of FLOVAC Spain, about vacuum sanitation in Ports and Marinas

The company FLOVAC Vacuum Sewerage Systems, is the world’s largest designer, manufacturer and supplier of complete vacuum sewerage systems Among its solutions, one of the fastest growing solutions is the complete sanitation of marinas and commercial ports, where a vacuum sewerage network allows the operator to manage the port’s own sanitation network and at the same time service the collection of wastewater from the boats.

Francisco, in general terms, how does a vacuum sanitation system installed in ports and marinas work?  

A Flovac valve connected to the vacuum network is installed at each connection point. When it detects that there is about 20 cm of water in the sump, the valve opens, sucks in the water, sucks in air and closes again in a matter of 2 or 3 seconds. All this without electricity, only with the force of the vacuum.

The only point that needs electricity is the vacuum station. The vacuum pumps located in the station maintain a constant vacuum level in the vacuum network that covers the entire port or marina. A tank collects the wastewater before being driven or pumped to the municipal collector or sewage treatment plant.

What advantages does this vacuum sanitation offer compared to traditional sanitation in this type of site? In marinas and ports, the water table is very high and has often been filled with breakwater, so deep ditches are extremely expensive and technically complicated. Thanks to the force of the vacuum, the pipes can be installed at a shallow depth and serve the entire port or marina with a single vacuum station. The wells where buildings and megayachts are poured can also be shallow, since the valve only needs 20 cm of water to act.

The vacuum station itself can be buried (for space or aesthetics) or it can be on the surface, without the need for excavation. Another advantage would be the absence of odors, since when emptying the well each time there is 20 cm of water (about 50 liters), the residence time is minimal and avoids the appearance of the smell characteristic of pumping. In addition, the valve remains open a couple of seconds after emptying the well, so it renews its air. The network of pipes is watertight, since any leakage is detected in the vacuum station and an alarm occurs. In addition, in case of leakage, air will be sucked through the fissure and no residual water will be spilled. Therefore, it is the only system that ensures correct environmental protection of the port or marina.

As for the installation costs of this technology and maintenance costs, replacement of equipment, etc., what can you tell us? The reduction of excavation in such difficult conditions as a port, means a reduction of important costs, and the reason why sewage collection by vacuum is the most economical solution. The maintenance costs of a system with a single vacuum station, compared to an alternative that would require multiple pumping, are also clearly lower. The valve is specifically designed to work with wastewater. They are manufactured in glass filled polypropylene, with a stainless steel shaft. The result is that the first valves installed in Spain, specifically in Empuriabrava, 15 years ago, continue to operate with a minimum consumption of spare parts

Currently FLOVAC is the benchmark in the installation of vacuum sewerage systems, both in residential areas and in ports and marinas, what are your main references and projects at this time in Spain? The first installations in ports that we carried out in Spain, more than 10 years ago, were sewerage projects for the existing buildings in the marinas or ports. Later, we added sewage suction points for small boats that had to move to that point. In the most recent marinas, a single vacuum station serves buildings, suction points for yachts located at the gas station, megayachts on their own mooring and even a network of bilge water suction points that are treated before they are sent to the public sewage system.

The result is that among our projects in Spain there are all kinds of facilities: large commercial ports, such as the Port of Barcelona or small ones such as Arenys de Mar, marinas for yachts or mega yachts such as the Royal Marina Juan Carlos I (Valencia), Port Vell and Marina Vela (Barcelona) or industrial facilities such as Marina Barcelona 92 ​​for megayacht repair.

To empty wastewater from small boats, suction points are available, usually next to the gas station. Likewise, Flovac valves open and allow the emptying of yacht deposits. The megayachts, on the other hand, have their own sewage pumps, which drive the water to small wells located on the same dock where Flovac valves evacuate the water to the vacuum station. Finally, to evacuate the bilge water from the gas stations, a second vacuum network is required, so that these waters end up in a different reservoir that allows their treatment before being sent to the public sewage system. But the equipment at the vacuum station is the same for both networks.

Finally, Francisco, are marina and port projects being installed in other countries?

Flovac is leading the world in providing sewerage solutions at Marina’s and many countries are now following Spain’s lead which we feel is a world leader in using best environmental practices. Greece has always been another leading country for marinas and we have done a number of projects as far away as Australia and more recently in the Caribbean, Italy is also a very good market for us.

For more information please visit www.flovac.es or www.flovac.com

Coping in a world with less water

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The Downside of Saving Water

In recent times severe water shortages in many parts of the world have led Water Authorities and consumers to rethink how water is used in households. Water restrictions in many areas have drastically cut the amount of potable water used, with car washing and garden watering severely restricted. Water savings devices have now been installed in many homes and many more products are now being developed. This is having a big impact on the way wastewater is taken from houses to be treated by municipal authorities.

Many municipalities will soon adopt policies allowing greywater to be re-used within the house or on the garden. Products such as water efficient showerheads, washing machines, and flow inhibitors on taps as well as low flush toilets are reducing how much wastewater is sent to the treatment plant for treatment. Community education programmes are also informing consumers about ways to reduce water use.

Wastewater can be categorised into two components; greywater and blackwater. The main difference between greywater and blackwater is the biological and solids content. Blackwater is essentially the water that has all of the solids in it and cannot come into contact with humans unless treated. Household wastewater can be broken down as follows:-

Greywater {f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} Blackwater {f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}
Showers Baths/Spa’s 33{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} Toilets 32{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}
Basin 5{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} Kitchen 7{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}
Laundry 23{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}
Total 61{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} 39{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def}

In most cities and towns wastewater moves from houses via a gravity reticulation network to the treatment plant, where it is treated to an acceptable level and sent to an ocean outfall or into the ground for further long term treatment or increasingly recycled for use in industry or public areas.

Gravity pipework is laid with sufficient grade (1/60;1/80;1/100) to allow for water to push any solids down the pipe toward a pump station which will bring it back to the surface and then gravitate again to the next pump station, until ultimately it will bring the wastewater to the treatment plant. The pipework will sometimes need to be installed quite deep (5-10 metres) to minimise the number of pump stations required.

The Problem

There is however a problem in that current gravity sewer networks cannot cope with lower water flows in pipes in that it is water that transports solids down the pipe. If there is insufficient water, then there is no movement.

Gravity sewer mains are usually designed to allow for a 14{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} solid load in the pipe. The other 86{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} is water pushing the solids down the pipe. What happens if the solid load is 50{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} as has recently happened in parts of drought affected Australia.

In previous years water authorities have designed their pipework and pump stations based on between 200-240 litres per person per day (l/p/d) There was also an allowance made for peaking factors (higher water use at peak times such as in the morning or evenings) and they have also allowed for the risk of stormwater infiltration, due to illegal connections or broken pipes. This stormwater allowance is usually 3 times the average daily allowance and can have very high cost impacts on the pipework, pump-station and treatment plant requirements.

The current water shortages and water saving devices as well as the separation of gray and black water have led to a reduction in daily allowances to 150-180 litres per person per day (l/p/d). This suggests that wastewater infrastructure can be smaller and therefore use less power but what has in fact been occurring is significantly higher maintenance requirements and even water use by the water authorities. As gravity systems require the use of water to move solids down the pipe network, less water coming from the household is creating blockages in greater numbers leading to odour problems as well as increased water and labour costs to manually flush the pipes of solids.

240 l/p/d 180 l/p/d 70 l/p/d *
Blackwater 94 70 70
Greywater 146 110 0
Total 240 180 70

* Greywater reuse at the house

In recent years many municipalities and water authorities have adopted the use of vacuum sewerage systems as their reticulation networks in areas where there is a high water table or very flat land or where it is too difficult to install a traditional gravity network. The very first vacuum sewers were installed in the late sixties but there has been a sharp increase in recent years as operators discover the lower operating cost versus their existing gravity systems. All pipework is laid at minimal depth and laid at a flat 1/500 grade. There is usually only one pump station required which has reduced the energy costs in the system. Differential air pressure is the driving principle and all solids and water are transported via air rather than water. The wastewater travels at a high velocity (4-6 metres per second) and so no blockages occur. As it is a tight system, damaged pipes are immediately repaired and no allowance is required for stormwater infiltration saving money and energy with the sizing of the infrastructure.

Vacuum systems have been used for many years to move 100{f2ac4d1e1d40dc2e2d9280a1dfa90d854b2d8c80eba743affa37fc4ce2e16def} solids this is common in many industrial applications and even in the home. This also applies to wastewater removal. The Flovac sewerage system can easily handle quite high concentrations of solids in the pipe.

Conclusion

For countries or towns with very little water available or have diminishing resources like Botswana, India, Oman, Australia and many others places, Flovac systems are really the only system that should be considered for removal of sewage.