Case Study: FERTIWRACK
Reed Bed System for Integrated Beach Wrack Management and Processing
Location: Swarzewo, Puck Bay, Poland
Lead: Gdańsk University of Technology
Beach wrack can be treated in a reed bed system (RBS). In the RBS integrated processes of dewatering and stabilization of beach wrack occur. Beach wrack processed in the RBS can be used as soil conditioner or fertilizer. Thanks to its natural appearance, the RBS can be built close to the beach and thus limiting the transport of collected beach wrack from the beach to the RBS. Additionally, the solution is low maintenance and no chemicals are needed.
The reject water - as a by-product of the dewatering process of the beach wrack - is filtered through the substrate of the RBS and undergoes a variety of treatment processes in the substrate layers. Accordingly, it can be stated that this specific RBS technology acts as a close to nature (or nature-based) solution for beach wrack management and the production of soil conditioner/fertilizer, since no artificial additives are used and by-products (reject water) are filtered via natural sand, graval and aggregate layers.
September 2020: On September 21 a monthly research session took place to discharge raw material into the reed bed system in Swarzewo. This time 45l of beach wrack material was collected, which alone or mixed with compost was used to flood appropriate quarters. September's beach wrack consisted of algae other than seagrass, which was a main ingredient in August. Due to lack of the place in quarter "C", it was supplied with a smaller amount of material: 5l of algae mixed with 5l of compost instead of 10l of algae mixed with 10l of compost.
Once again, very small amounts of reject water were collected for testing: from "A-D" deposit- 600ml and 0ml from the "E-H" bed.
August 2020: On August 20 another beach wrack material collection took place and the reed bed system in Swarzewo was supplied. The entire research session was similar to the previous months. However, this time, 50l beach wrack was collected, which mainly consisted of sea grass.
Unlike previous research sessions, two quarters were additionally supplied:
-quarter "G" à 5l of shredded algae
-quarter "H"à 5l of shredded algae mixed with compost.
Due to very low rainfall and high temperatures on the Polish Baltic coast, a small amount of reject water was collected. From left cube a total of 910 ml was obtained from all quarters, and from right cube only one quarter was supplied four times, collected amount of reject water was zero. Due to hot weather, bed was additionally watered with treated wastewater from stabilization ponds of Swarzewo WWTP in order to ensure appropriate vegetation conditions for the reed: left cubic - 5l, right cubic - 20l.
July 2020: On July 21st, another beach wrack material collection took place in order to supply the reed bed system. The material from reed system as well as reject water was collected to conduct research at the Department of Water and Wastewater Technology at the Gdańsk University of Technology. Again, the material was collected from the coastal waters of Rzucewo beach using a landing net. The collected material showed decomposition characteristics, which may be related to the high temperatures at the Polish coast.
Beach wrack alone or mixed with compost was delivered to the reed system in the same amounts and proportions as in June. The amounts of both reject water from reed bed and after the fresh material supplying were very low. In both cases amounting to approx. 300 ml. Such small amounts of reject water were caused by the high temperatures and the use of water by the reed as well as the fact that the beds were fed with partially fermented material, which drains worse than "fresh" material.
June 2020: For the third time, beach wrack was supplied to a reed bed pilot system. Material for research was also collected. Collection of algae took place in coastal waters of the beach in Rzucewo. Due to the lack of wind, it was difficult to find fresh material. Finally, the “old” beach wrack material (on high stage of decomposition, indicated by consistency, color and smell) was collected. In addition, sand from beach was collected for the purpose of granulometric analysis, necessary to assess impact of sand content in deliver material on substrate clogging process. Both beach wrack and compost material were delivered to quarters in the same proportions as in previous session. Before suppling of the fresh material to reed bed system, reject water and deposit material were collected used for further testing by a team from the Department of Water and Wastewater Technology from GUT. It was found that the reed bed pilot system well dewatered the beach wrack material. This is indicated by the volume of reject water which was in the pilot object one month after supply. In the case of the object where three quarters were flooded, the total volume was approx. 6l, and in the second one where only one quarter was fed about 1.8l was found. It should be taken into account that volume of reject water obtained was reduced by water that outflow immediately after suppling, reject water used for needs of reed as well as lost in the evapotranspiration process. Another observation concerns the fact that beach wrack material is a source of nutrients for reed and has a positive effect on its growth. This indicates good fertilizing properties (see pictures).
May 2020: The research team from the Gdańsk University of Technology took further steps forward: The May supply of beach wrack material collected in Rzucewo, has been transported to the model object - the reed bed system located at the WWTP in Swarzewo. As last time, forty liters of beach wrack were collected and discharged in the same amounts and ratios of mixing with compost as in April (to four quarters of the reed bed system). Before recharging, wastewater and April material from the deposit were collected for research conducted at the Gdańsk University of Technology. Samples of raw material were also analysed at the laboratory.Further activities related to the deposits supply and research are planned end of June.
April 2020: The research team from the Gdańsk University of Technology discharged the beach wrack to the pilot plant installation. The material was collected from the coastal waters of the beach in Rzucewo. Forty liters of beach wrack was collected and used to fed four quarters of the reed system, consisted the model located in the Wastewater Treatment Plant in Swarzewo:
- 10l algae;
- 15l algae;
- 10l of algae mixed with 10l of compost;
- 5l algae mixed with 5l compost.
The flow rate was measured in two quarters: first fed with beach wrack and second one fed with beach wrack mixed with compost in 1: 1 ratio. Basic quality determinations were carried out on the collected reject water. Samples of raw beach wrack and material discharged to the reed system last autumn were also taken. The next activities related with discharging of beach wreck to the system are planned for the end of May.
November 2019: Beach wrack was collected from Rzucewo's beach. Due to the small amount of collected material, only one quater of deposit was supplied to evaluate the beach wrack material behavior in the reed bed system. Samples of material for tests in the laboratory were also taken.
October 2019: Pilot facility at the wastewater treatment plant (wtp) in Swarzewo has been installed. Over the next 12 months we'll test beach wrack as a co-composting material in wetland technology.
August 2019: Article "Solving the Beach Wrack Problems by On-Site Treatment with Reed Beds Towards Fertilizer Amendments" published in the Journal of Ecological Engineering (JEE), Volume 20, Issue 8, 2019. Available for download here.
The CONTRA partners are from Germany, Poland, Denmark, Sweden, Russia and Estonia. The project runs from 2019 to 2021 and is supported financially by the European Regional Development Fund, ERDF.