Less effort in ecological water purification

Researchers at the Insti­tute for Water and Ener­gy Man­age­ment (iwe) at Hof Uni­ver­si­ty of Applied Sci­ences want to reduce the amount of labor and mate­ri­als used in pond man­age­ment. This is to be achieved with the help of biodegrad­able, so-called “growth bod­ies” for water purifi­ca­tion. These could soon replace con­ven­tion­al plas­tic purifi­ca­tion ele­ments and thus also reduce microplas­tics in water and fish. The research project on this has been run­ning since April 2021.

Aqua­cul­ture is one of the fastest grow­ing food sec­tors, with annu­al pro­duc­tion worth $250 bil­lion. Grow­ing bod­ies are an indis­pens­able part of this: thanks to their large sur­face area on which bac­te­ria set­tle, they help to con­vert tox­ic ammo­ni­um and nitrite into less harm­ful nitrate. At the same time, this saves water and pro­tects the envi­ron­ment. But growth bod­ies are usu­al­ly made of plas­tic or oth­er petro­le­um-based plastics.

“Recy­cling them is cost­ly, and plas­tic in the world’s oceans and waters pos­es a major chal­lenge to human­i­ty — plas­tic can even­tu­al­ly turn into microplas­tics, which we ingest our­selves through our food, and which in any case have a harm­ful effect on the envi­ron­ment and its organisms.”

- Dr. Har­vey Har­bach, respon­si­ble for the aquapon­ics research area

Bioplastics instead of plastics

In gen­er­al, there­fore, it is impor­tant to find sub­stances that can replace con­ven­tion­al plas­tic. In the case of grow­ing bod­ies, the obvi­ous mate­r­i­al to use is bio­plas­tic. A team of researchers from the Insti­tute for Water and Ener­gy Man­age­ment (iwe) at Hof Uni­ver­si­ty of Applied Sci­ences, led by project man­ag­er and idea gen­er­a­tor Dr. Har­vey Har­bach, is work­ing on pre­cise­ly this: In col­lab­o­ra­tion with the Insti­tute for Biopoly­mer Research (ibp), which is also based at Hof Uni­ver­si­ty of Applied Sci­ences, and a com­mer­cial enter­prise from Fran­co­nia, com­plete­ly biodegrad­able growth bod­ies for bio­log­i­cal water treat­ment have been devel­oped since the begin­ning of April 2021 under the project name “Bio­Bio­Car­ri­er.” The project, which will run until 2023, is fund­ed by the Ger­man Fed­er­al Min­istry for Eco­nom­ic Affairs and Ener­gy as part of the Cen­tral Inno­va­tion Pro­gram for SMEs (ZIM).

Testing different materials

“The dif­fi­cul­ties in the project lie in the cor­rect selec­tion of biopoly­mers and the asso­ci­at­ed degrad­abil­i­ty in water. The new growth body must not degrade too quick­ly in fresh water,” explains project team mem­ber Ms. Christin Baum­gart. By com­bin­ing dif­fer­ent poly­mers with each oth­er, new prop­er­ties are to be gen­er­at­ed: “This means that the biodegrad­abil­i­ty in water can be adjust­ed.” How­ev­er, the results so far look promis­ing. Accord­ing­ly, progress has already been made and solu­tions iden­ti­fied. How­ev­er, a num­ber of hur­dles still need to be over­come before the prod­uct is ready for the mar­ket: “When select­ing sub­stances, care is tak­en to ensure that they are not harm­ful to health. Since the appli­ca­tion is in aquapon­ics, the sub­stances must also be suit­able for the fish and plants. This means that great atten­tion is paid here to the harm­less­ness of the sub­stances, all should be biodegrad­able and even bio-based.” Fur­ther, “but biodegrad­abil­i­ty would also still need to be looked at in detail to make sure they decom­pose in the time frame given.”

New development beckons

A key chal­lenge in the project, but one that could rep­re­sent a break­through with­in the indus­try con­cerned, could ulti­mate­ly be pro­vid­ed by a new devel­op­ment cur­rent­ly being worked on in Hof: “In aquapon­ic sys­tems, nutri­ents have to be added at reg­u­lar inter­vals, with­out which plants can­not grow or can only grow poor­ly. Our idea is to com­bine the biodegra­da­tion of the prod­uct with the release of the sub­stances need­ed by the plants. This would con­se­quent­ly reduce work­ing time and improve prof­itabil­i­ty,” says Dr. Har­bach. And he con­tin­ues: “There are cur­rent­ly no com­pa­ra­ble prod­ucts on the mar­ket. This would be a real inno­va­tion. We are work­ing at full speed and expect fur­ther results soon.”