Population dynamics of free-swimming Annelida in four Dutch wastewater treatment plants in relation to process characteristics

Free-swimming Annelida occasionally occur in very high densities in WWTPs (WasteWater Treatment Plants) and are nowadays applied for waste sludge reduction, but their growth is uncontrollable. In order to get more insight in the population dynamics of these free-swimming Annelida, and relate their presence to process characteristics, nine ATs (Aeration Tanks) of four Dutch WWTPs were regularly sampled over a 2.5-year period. For each species, peak periods in worm population growth were defined and population doubling times and half-lives calculated. Peak periods and doubling times were compared to those in natural systems. Process characteristics were obtained from the plant operators and related to the worm populations by multivariate analysis for the first time in large-scale WWTPs. The species composition in the WWTPs was limited and the most abundant free-swimming Annelida were in decreasing order Nais spp., Aeolosoma hemprichi, Pristina aequiseta, Aeolosoma variegatum, Chaetogaster diastrophus, and Aeolosoma tenebrarum.This latter species had never been found before in WWTPs. Worm absence sometimes coincided with the presence of anoxic zones, but this was possibly overcome by higher temperatures in the WWTPs. Worms were present all year round, even in winter, but no yearly recurrences of population peaks were observed, probably as a result of stable food supply and temperature, and the lack of predation in the WWTPs. Peak periods were similar between the ATs of each WWTP. The duration of the peak periods was on average 2¿3 months for each species and the population doubling times in the peak periods were short (on average 2¿6 days), which also corresponds to a stable favorable environment. The disappearance of worm populations from the WWTPs was presumably caused by declining asexual reproduction and subsequent removal with the waste sludge. Multivariate analysis indicated that 36% of the variability in worm populations was due to spatial and temporal patterns only. In addition, no more than 4% of the variability in worm populations was related to variations in process characteristics only and worm presence was usually associated with better sludge settleability. In conclusion, our data from large-scale WWTPs suggest that growth of free-swimming Annelida still seems uncontrollable and that their effects on treatment processes are unclear, which makes stable application in wastewater treatment for sludge reduction difficult

Productie van zoutwateralgen voor toepassingen in food (en feed) deelrapport I : Werkpakketten 1&2 van project Foodgrade productie van zoutwateralgen: deelrapport I: Achtergrondinformatie zoutwateralgen: selectie van soorten en omgevingsomstandigheden

The commercial production of microalgae for food applications has been the focus of much attention lately. Culturing marine microalgae in reactors with LED lamps has several advantages. Marine algae contain valuable components such as antioxidants, which are described in this report, and high salinities in production systems can lead to less contamination. By producing them in closed systems at different LED light wavelengths (colours) high biomass concentrations can be obtained and production of biomass and valuable components can be increased. This report summarizes interesting components (i.e. pigments, lipids, carbohydrates) from marine microalgae in addition to general effects of light, nutrients, salt, pressure and mutations on algae growth. The influence of several parameters on biomass growth and pigment formation of several commercially interesting marine algae species is described. These parameters include light intensity, wavelength, light path length, nitrogen source and concentration, mutagens, dilution/refreshment rates, mixing conditions, temperature, salt concentration, flashing (alternating L/D cycles), mixotrophic/phototrophic conditions, alternative nutrient sources, mixed cultures and Si addition. Species that are described in detail include Dunaliella salina and tertiolecta, Arthrospira platensis, Nannochloropsis gaditana and sp., Phaeodactylum tricornutum, Porphyridium purpureum, Tetraselmis chuii, Odontella aurita and Odontella sinensis

Productie van zoutwateralgen voor toepassingen in food (en feed) deelrapport II : Werkpakketten 1&2 van project Foodgrade productie van zoutwateralgen: deelrapport II: Batchexperimenten met zoute reststromen en verschillende mariene algensoorten

There is a lot of interest in the commercial production of microalgae for food applications. Producing marine microalgae in reactors with LED lights has several advantages. Marine microalgae contain valuable components such as antioxidants, and high salinity levels in production systems can prevent contaminations with other organisms. Production in closed systems at different light wavelengths (colours) can result in high biomass concentrations and better control of biomass growth and production of valuable components. Several industries produce salt waste streams, often with associated processing costs. In this report a number of these streams is discussed (liquid fraction of cattle manure biogas slurry, potassium and sodium brines from dairy industries, brackish groundwater, seawater, purge water and brine from salt processing). An option for reducing costs (for disposal or treatment) is the production of marine microalgae on these streams. The algae can be used as food (ingredient). This report describes batch experiments in which growth of nine microalgae species was tested on these waste streams: Nannochloropsis gaditana, Phaeodactylum tricornutum, Tetraselmis chuii (two strains), Porphyridium purpureum, Dunaliella salina, Odontella aurita, Arthrospira platensis and Tetraselmis tetrathele. The experiments were performed in well plates and 1 L reactors with artificial (LED) lights. From the tests it was concluded that several of the algae species can be cultured on different waste streams. The best results were obtained with N. gaditana, A. platensis, P. purpureum en T. chuii (AF&F) on (diluted) brines from the dairy industry and the diluted liquid fraction of biogas slurry. It is recommended to optimize some of these combinations further in experiments

Valorising side streams in circular animal feed additives : Opportunities and challenges

Because of a growing world population there is an increasing need for protein production, in addition to traditional agriculture and fisheries. Several new crops such as microalgae, macro algae, aquatic higher plants, aquatic and terrestrial invertebrates (insects and worms) have received growing scientific attention, because of potential high biomass yields for protein production on small surface areas. Several side streams (flue gas, residual heat, biogas slurry and solid wastes) can be valorised in their cultivation. Combining bioenergy production and its side streams with cultivation of these circular crops, improves economy and sustainability of both.At the ACRRES site, Wageningen University runs pilot facilities together with several SMEs. The research is aimed at innovating and improving economics of alternative crop production and energy use efficiency. The main focus is on utilization of microalgae and other novel crops to benchmark this with conventional feeds. Data on their value as feed ingredient and from optimized production systems are used as input for legislation matters with regard to nutrient use and feed safety. In addition to their suitable macro composition research indicates that some circular feed components have added value to improve animal health and final quality of the animal end products.<br/

Sludge reduction by aquatic worms in wastewater treatment : with emphasis on the potential application of Lumbriculus variegatus

In wastewater treatment plants (WWTPs), large amounts of biological waste sludge are produced. In the Netherlands, the application of this sludge in agriculture or disposal in landfills is no longer allowed, mainly because of its high heavy metal content. The sludge therefore generally is incinerated. Sludge processing costs are estimated to be half of the total wastewater treatment costs. This thesis focuses on the application of aquatic worms to reduce the amount and volume of the excess sludge. Several worm species, belonging to the Aeolosomatidae, Tubificidae (including Naidinae) or Lumbriculidae have specific characteristics that could make them suitable for such an applicatio

Method for releasing aquatic worms from a carrier and predation reactor

The invention relates to a method comprising providing a carrier, preferably a porous carrier, comprising a number of aquatic worms from the class of the Oligochaeta exhibiting a swimming motion. The method further comprises providing to the worms an escape reflex-inducing stimulus on at least one side of the carrier of, such that the worm biomass is at least partially released from the carrier. The method further comprises removing worm biomass released from the porous carrier for further processing. The invention further relates to a predation reactor suitable for applying the method according to the invention

Extraction of steviol glycosides from fresh Stevia using acidified water; clarification followed by ultrafiltration and nanofiltration

As part of the PPS Kleinschalige bioraffinage project (WP1b), fresh Stevia material was used in the extraction of steviol glycosides using water acidified through conversion of sugar by microorganisms naturally present on the plant. Two successive harvests from the same plot were used. Previous experiments had resulted in high steviol glycoside extraction rates of 80 % to 90 % but the purity of the final extract was low (15 % to 20 % of steviol glycosides in the dry matter). The first batch of plants was used to test a clarification step by filtration on a small scale. A second batch of plants was used to perform clarification, purification using ultrafiltration, and concentration by nanofiltration on a larger scale

PHA’s (Polyhydroxyalkanoates): General information on structure and raw materials for their production : A running document for “Kleinschalige Bioraffinage WP9: PHA”, Task 5

This report provides background information on structure and diversity of different polyhydroxyalkanoates (PHA) and on feedstocks for their microbial production. The information that is contained in this report was compiled as a running document for the project “TKI-AgriFood Kleinschalige Bioraffinage” Work Package 9: “Fatty acid and PHA production based on residues” (In Dutch: “Vetzuuren PHA-productie op basis van residuen”) (TKI-AF-12040), and should be seen as such: a compilation of information regarded as interesting for the project partners

Productie van zoutwateralgen voor toepassingen in food (en feed) deelrapport II : Werkpakketten 1&2 van project Foodgrade productie van zoutwateralgen: deelrapport II: Batchexperimenten met zoute reststromen en verschillende mariene algensoorten

There is a lot of interest in the commercial production of microalgae for food applications. Producing marine microalgae in reactors with LED lights has several advantages. Marine microalgae contain valuable components such as antioxidants, and high salinity levels in production systems can prevent contaminations with other organisms. Production in closed systems at different light wavelengths (colours) can result in high biomass concentrations and better control of biomass growth and production of valuable components. Several industries produce salt waste streams, often with associated processing costs. In this report a number of these streams is discussed (liquid fraction of cattle manure biogas slurry, potassium and sodium brines from dairy industries, brackish groundwater, seawater, purge water and brine from salt processing). An option for reducing costs (for disposal or treatment) is the production of marine microalgae on these streams. The algae can be used as food (ingredient). This report describes batch experiments in which growth of nine microalgae species was tested on these waste streams: Nannochloropsis gaditana, Phaeodactylum tricornutum, Tetraselmis chuii (two strains), Porphyridium purpureum, Dunaliella salina, Odontella aurita, Arthrospira platensis and Tetraselmis tetrathele. The experiments were performed in well plates and 1 L reactors with artificial (LED) lights. From the tests it was concluded that several of the algae species can be cultured on different waste streams. The best results were obtained with N. gaditana, A. platensis, P. purpureum en T. chuii (AF&F) on (diluted) brines from the dairy industry and the diluted liquid fraction of biogas slurry. It is recommended to optimize some of these combinations further in experiments