Testing the effectiveness of the SKIM foam fractionator to reduce nutrient levels in prawn farm effluent

To experimentally investigate the effect of the “SKIM” mechanical foam fractionator on suspended material and the nutrient levels in prawn farm effluent, a series of standardised short-term treatments were applied to various effluent types in a static 10,000-litre water body. Prawn pond effluents were characterised by watercolour and dominance of phytoplankton species. Three effluent types were tested, namely 1) particulate-rich effluent with little apparent phytoplankton, 2) green mircoalgal bloom predominately made up of single celled phytoplankton, and 3) brown microalgal bloom with higher prevalence of diatoms. The effluent types were similar (P>0.05) in non-volatile particulate material, and nitrate/nitrite but varied from each other in the following ways: 1) The particulate-rich effluents were lower (P<0.05) in volatile solids (compared to brown blooms), total Kjeldahl nitrogen, dissolved organic nitrogen, dissolved organic phosphorus and chlorophyll a (compared to both green and brown blooms). 2) The brown blooms were higher (P<0.05) in ammonia (compared to green blooms), total nitrogen and total phosphorus (compared to both green and particulate-rich effluent), but were lower (P<0.05) in inorganic phosphorus (compared to both green and particulate-rich effluent). 3) The green blooms were higher (P<0.05) in dissolved (both organic and inorganic) phosphorus (compared to both brown and particulate-rich effluents). Although the effluent types varied significantly in these aspects the effect of the Skim treatment was similar for all parameters measured except total phosphorus. Bloom type and Skim-treatment period significantly (P<0.05) affected total Kjeldahl phosphorus concentrations. For all effluent types there was a continuous significant reduction (P<0.05) in total Kjeldahl phosphorus during the initial 6-hour treatment period. Levels of total suspended solids and volatile suspended solids in all effluent types were significantly (P<0.05) reduced in the first 2 hours but not thereafter. Non-volatile suspended solids were also significantly (P<0.05) reduced in the first 2 hours (30 to 40 % reduction) and a further 40% reduction occurred in the particulate-rich effluent over the next 2 hours. Mean values for total ammonia, dissolved organic nitrogen, total Kjeldahl nitrogen, total nitrogen, chlorophyll a and dissolved organic or inorganic phosphorus levels were not significantly (P>0.05) affected by the Skim unit in any bloom type during the initial 6 hours of testing. Nevertheless, non-significant nitrogen reductions did occur. Foam production by the Skim unit varied with different blooms, resulting in different concentrate volumes and different end points for separate experiments. Concentrate volumes were generally high for the particulate-rich and green blooms (175 – 370 litres) and low for the brown blooms (25 – 80 litres). This was due to the low tendency of the brown bloom to produce foam. This generated higher nutrient concentrations in the associated condensed foam, but may have limited the treatment efficiency. The results suggest that in this application, the Skim unit did not remove micro-algae as effectively as was anticipated. However, it was effective at removing other suspended solids. Considering these attributes and the other uses of this machinery documented by the manufactures, the unit’s oxygenation mixing capacities coupled with inorganic solids removal may provide a suitable mechanism for construction of a continuously mixed bioreactor that utilises the filtration and profit making abilities of bivalves.

The influence of temperature on the foaming of milk

The effect of temperature (5-85 °C) on the foaming properties of cows' milk was investigated. The foaming properties of milk as a function of temperature varied considerably depending on fat content and the processing conditions used in manufacture. Skim milk foams were most stable when formed at 45 °C. Milk fat had a detrimental effect on foam formation and stability of whole milk especially in the temperature range 15-45 °C. The detrimental effects of milk fat on foaming properties were reduced by homogenization and ultra-high-temperature (UHT) treatment. No correlation was observed between foam formation and surface tension of whole milk in the temperature range 15-45 °C. There was a pronounced difference in the bubble size distributions of whole milk and skim milk especially at half-life of the foams. Bubbles in whole milk foams were smaller and showed a higher degree of rupture as a result of coalescence than those in skim milk foams.

A new culture method for lesser mealworm, Alphitobius diaperinus

A new culture method for lesser mealworm, Alphitobius diaperinus (Panzer), was developed to provide large numbers of adult lesser mealworms of approximately the same age for insecticide resistance testing. Culturing entailed allowing 100 adults to reproduce for 4 days in a wheat-based culture medium contained inside a plastic culture box, removing the adults from the medium, and then rearing their progeny to adulthood therein, in approximately 56 days at 32 degrees C and 55% RH. During their development, progeny were supplied water via apple slices at 0, 21 and 35 days, and a foam substrate in which to pupate, also at 35 days. During 2004-2005, adult lesser mealworms were collected from six broiler-house populations and then cultured with this method. Each population produced 4500 adults required to complete resistance testing with one insecticide within ten culture boxes, at an average of 798 adults per culture box.

Fungal Planet description sheets: 128-153

Novel species of microfungi described in the present study include the following from Australia: Catenulostroma corymbiae from Corymbia, Devriesia stirlingiae from Stirlingia, Penidiella carpentariae from Carpentaria, Phaeococcomyces eucalypti from Eucalyptus, Phialophora livistonae from Livistona, Phyllosticta aristolochiicola from Aristolochia, Clitopilus austroprunulus on sclerophyll forest litter of Eucalyptus regnans and Toxicocladosporium posoqueriae from Posoqueria. Several species are also described from South Africa, namely: Ceramothyrium podocarpi from Podocarpus, Cercospora chrysanthemoides from Chrysanthemoides, Devriesia shakazului from Aloe, Penidiella drakensbergensis from Protea, Strelitziana cliviae from Clivia and Zasmidium syzygii from Syzygium. Other species include Bipolaris microstegii from Microstegium and Synchaetomella acerina from Acer (USA), Brunneiapiospora austropalmicola from Rhopalostylis (New Zealand), Calonectria pentaseptata from Eucalyptus and Macadamia (Vietnam), Ceramothyrium melastoma from Melastoma (Indonesia), Collembolispora aristata from stream foam (Czech Republic), Devriesia imbrexigena from glazed decorative tiles (Portugal), Microcyclospora rhoicola from Rhus (Canada), Seiridium phylicae from Phylica (Tristan de Cunha, Inaccessible Island), Passalora lobeliaefistulosis from Lobelia (Brazil) and Zymoseptoria verkleyi from Poa (The Netherlands). Valsalnicola represents a new ascomycete genus from Alnus (Austria) and Parapenidiella a new hyphomycete genus from Eucalyptus (Australia). Morphological and culture characteristics along with ITS DNA barcodes are also provided. © 2012 Nationaal Herbarium Nederland & Centraalbureau voor Schimmelcultures.