Improving the Ecological Status of Surface Waters Through Filtration on Hemp (Cannabis sativa L.) Waste as an Option for Sustainable Surface Water Management

Abstract

The progressive degradation of surface waters should become one of the most important problems requiring an urgent solution. One of the methods developed is filtering water through loose, degraded sediments, blooms of cyanobacteria or algae, or a bed of hemp (Cannabis sativa L.) waste or hemp fibers. The conducted tests on the percolation of water samples and/or water with sediment from surface waters at sites with different ecological statuses indicate the possibility of using hemp waste for the reclamation of water reservoirs and rivers. The effect of filtration is a rapid improvement in water quality and, consequently, an improvement in the ecological status. The best result was achieved for a small freshwater reservoir with a large number of algae and loose degraded sediment. The initial turbidity value was at the limit of the device’s measurement capability, reaching 9991 NTU. After filtration through the hemp waste bed, the turbidity dropped to 42.52 NTU, a 99.57% decrease. The remaining parameters, C, TDS, and pH, were not subject to significant variability as a result of filtering. Excessive amounts of organic matter, which create a problem for surface waters, are removed. Due to the carrier (hemp waste), which is organic waste, any possible release of small amounts into the aquatic environment will not pose a threat. After applying filtration, a decision can be made on further actions regarding the water reservoir or river: Self-renewal of the reservoir or further percolation using, for example, mill gauze or cleaning the reservoir with other, non-invasive methods. After the filtering procedure, the hemp waste, enriched with organic matter and water remaining in the waste, can be used for composting or directly for soil mulching (preliminary tests have yielded positive results). A hemp waste filter effectively removes Chronomus aprilinus larvae (Chrinomidae) from water. This result indicates the possibility of removing mosquito larvae in malaria-affected areas. The use of hemp filters would reduce the amount of toxic chemicals used to reduce mosquito larvae. Improving the ecological status of surface waters by filtering contaminants with hemp waste filters can reduce the need for chemical treatment. The use of natural, biological filters enables sustainable surface water management. This is crucial in today’s rapidly increasing chemical pollution of surface waters.