Coupling of Anaerobic Digestion and Struvite Precipitation in the Same Reactor: Effect of Zeolite and Bischofite as Mg2+ Source

The aim of this research was to assess the simultaneous effect of zeolite and bischofite on estruvite production in an anaerobic digester treating pig slurry as substrate. Three ratios (5:1, 6:1 and 7:1) of Mg-P were used for evaluating the effect of only bischofite on anaerobic digestion. For assessing the simultaneous effect of zeolite and bischofite on anaerobic digestion, three mass ratios of zeolite:bischofite (1, 5 and 10%) were used. As results, bischofite as Mg+2 source served to decrease the total phosphorous (TP) concentration in the anaerobic digestion of pig manure without affecting the maximum methane production rate or methane yield of the system. An average 82.5% TP removal was found in the reactors with bischofite during the first 5 days of digestion. Nevertheless, bischofite increased the lag-phase of the system. The simultaneous presence of zeolite and bischofite (1% ratio with respect to bischofite) caused a TP removal of 65.6% and increased the methane yield by up to 19.9% compared to a system without zeolite or bischofite. Thus, it is feasible to use bischofite and zeolite as enhancers for the simultaneous production of biogas and struvite inside an anaerobic digester treating piggery wastewater.

Effects of Aquaculture on the Shallow Lake Aquatic Ecological Environment of Lake Datong, China

Background: Lake Datong has undergone several stages of aquaculture from 1980 to 2017, with a rapid increase in fish production and inorganic fertilizer supplementation at every stage. Its water quality has been deteriorating since the introduction of aquaculture. The major pollutants are total phosphorus and total nitrogen, and the lake displays moderate eutrophication. In the present study, we used historical hydrobiont data, diatom inferred-total phosphorous (DI-TP) data, and an Ecopath model to explore the effects of aquaculture on the shallow lake aquatic ecological environment.Results: According to the DI-TP data, before 1930, Lake Datong was in a mesotrophic state (50–60 μg/L DI-TP). Between 1930 and 1980, the number of nutrient-tolerant species increased slightly, which indicates an increase in nutrient enrichment in the lake (66–83 μg/L DI-TP). From the 1980s to 2010 and especially since 2000, eutrophication increased rapidly, with eutrophic species dominating the diatom assemblage. The annual average DI-TP concentration was 202 μg/L. After 2010, the nutritional level dropped to 127–152 μg/L DI-TP. In 2019, consumer biomass in Lake Datong was relatively low, and biomass of submerged hydrophytes was relatively high, indicating that a high amount of primary produce could not be exploited by consumers and therefore, could not enter the food web. This led to reduction in the energy transfer efficiency (TE) of the ecosystem. Therefore, aquatic ecology management plans ought to be formulated in future, with focus on removing macrophytes, stocking herbivorous and omnivorous fish.Conclusions: Lake Datong has experienced four stages of nutritional succession following the introduction of aquaculture activities. Its aquatic ecological environment has experienced dramatic changes in the composition and biomass of its aquatic life. The Ecopath model illustrated the instability of the lake’s ecological environment. Owing to low consumer biomass and high submerged macrophyte biomass, a substantial quantity of primary produce remained unused by consumers. It was therefore, unable to enter the food web and led to reduction in the energy TE of the ecosystem. Our results provide important reference values and theoretical support for decision-makers and stakeholders in the subsequent management of similar shallow lake water ecosystems.

Using Rhizosphere Phosphate Solubilizing Bacteria to Improve Barley (Hordeum vulgare) Plant Productivity

On average less than 1% of the total phosphorous present in soils is available to plants, making phosphorous one of the most limiting macronutrients for crop productivity worldwide. The aim of this work was to isolate and select phosphate solubilizing bacteria (PSB) from the barley rhizosphere, which has other growth promoting traits and can increase crop productivity. A total of 104 different bacterial isolates were extracted from the barley plant rhizosphere. In this case, 64 strains were able to solubilize phosphate in agar plates. The 24 strains exhibiting the highest solubilizing index belonged to 16 different species, of which 7 isolates were discarded since they were identified as putative phytopathogens. The remaining nine strains were tested for their ability to solubilize phosphate in liquid medium and in pot trials performed in a greenhouse. Several of the isolated strains (Advenella mimigardefordensis, Bacillus cereus, Bacillus megaterium and Burkholderia fungorum) were able to significantly improve levels of assimilated phosphate, dry weight of ears and total starch accumulated on ears compared to non-inoculated plants. Since these strains were able to increase the growth and productivity of barley crops, they could be potentially used as microbial inoculants (biofertilizers).

Determination of NPS Pollutant Unit Loads from Different Landuses

This study aimed to estimate pollutant unit loads for different landuses and pollutants that reflected long-term runoff characteristics of nonpoint source (NPS) pollutants and recent environmental changes. During 2008–2014, 2026 rainfall events were monitored. The average values of antecedent dry days, total rainfall, rainfall intensity, rainfall duration, runoff duration, and runoff coefficient for each landuse were 3.8–5.9 d, 35.2–65.0 mm, 2.9–4.1 mm/h, 12.5–20.4 h, 12.4–27.9 h, and 0.24–0.45, respectively. Uplands (UL) exhibited high suspended solids (SS, 606.2 mg/L), total nitrogen (TN, 7.38 mg/L), and total phosphorous (TP, 2.27 mg/L) levels, whereas the runoff coefficient was high in the building sites (BS), with a high impervious surface ratio. The event mean concentration (EMC) for biological oxygen demand (BOD) was the highest in BS (8.0 mg/L), while the EMC was the highest in BS (in the rainfall range <10 mm) and UL and forest land (in the rainfall range >50 mm). The unit loads for BOD (1.49–17.76 kg/km2·d), TN (1.462–10.147 kg/km2·d), TP (0.094–1.435 kg/km2·d), and SS (15.20–327.70 kg/km2·d) were calculated. The findings can be used to manage NPS pollutants and watershed environments and implement relevant associated management systems.

Cyanophage Distribution Across European Lakes of the Temperate-Humid Continental Climate Zone Assessed Using PCR-Based Genetic Markers

Studies of the diversity and distribution of freshwater cyanophages are generally limited to the small geographical areas, in many cases including only one or few lakes. Data from dozens of various lakes distributed at a larger distance are necessary to understand their spatial distribution and sensitivity to biotic and abiotic factors. Thus, the objective of this study was to analyze the diversity and distribution of cyanophages within the infected cells using marker genes (psbA, nblA, and g91) in 21 Polish and Lithuanian lakes. Physicochemical factors that might be related to them were also analyzed. The results demonstrated that genetic markers representing cyanophages were observed in most lakes studied. The frequently detected gene was psbA with 88% of cyanophage-positive samples, while nblA and g91 were found in approximately 50% of lakes. The DNA sequence analyses for each gene demonstrated low variability between them, although the psbA sequences branched within the larger cluster of marine Synechoccocuss counterparts. The principal component analysis allowed to identify significant variation between the lakes that presented high and low cyanobacterial biomass. The lakes with high cyanobacterial biomass were further separated by country and the different diversity of cyanobacteria species, particularly Planktothrix agardhii, was dominant in the Polish lakes and Planktolyngbya limnetica in the Lithuanian lakes. The total phosphorous and the presence of cyanophage genes psbA and nblA were the most important factors that allowed differentiation for the Polish lakes, while the pH and the genes g91 and nblA for the Lithuanian lakes.

Influence of environmental regulations on eutrophication by the example of ukrainian legislation on total phosphorous

Since phosphates are ones of the key components causing eutrophication of water bodies, every country has to have clear legislation on them. Comparing standards of the EU and Ukraine concerning total phosphorous in wastewater, effluents from wastewater treatment plants (WWTPs), drinking water, and consumer detergents, the paper shows how the difference of legislation makes legal the eutrophication of water bodies in Ukraine. As demonstrated, the current Ukrainian regulations do not oblige strictly municipal WWTPs to remove phosphorus compounds from wastewater, although the EU has rigid requirements therein. Instead, Ukraine forbids discharging wastewater with more than 5 mg/l of total phosphorous into the municipal sewage system, though many local regulations in EU-countries allow higher values, e.g. such cities of Germany as Berlin, Hannover, and Düsseldorf permit up to 50 mg/l of total phosphorous in their municipal sewage systems. This is mostly because only natural human metabolism causes up to 10 mg/l of total phosphorous in wastewater, so, to reduce total phosphorous to 5 mg/l, every domestic house would oblige to have its own WWTP. All this leads to the situation where water companies in Ukraine, instead of modernization their 30-40 years old WWTPs, fine their clients due to the steep requirements. For instance, the municipal water company Khmelnitskvodokanal won the case No 20/4901 against the company “Khmelnitsk plant of experimental production” that discharged into the municipal sewage system in the town of Khmelnitsk its wastewater with 17.42 mg/l phosphates (or 5.68 mg/l as total phosphorous), usual concentration for the EU. Moreover, phosphonates in detergents also contribute to the eutrophication. Another problem is that, due to the lack of trained qualified staff, the amount of total phosphorous determined in different laboratories in the same sample of water may differ by several times.

P- SOLUBILIZING MICROORGANISMS PERFORMANCE ON MANURE AND ROCK PHOSPHATE AND THEIR INFLUENCES ON SOIL AND PLANT PHOSPHOROUS IN CALCAREOUS SOILS

Phosphate solubilizing microorganisms were isolated in vitro experiment, and wheat crops were planted in pots for 5 months and treated with rock phosphate, manure and with combination treatments of rock phosphate, manure, and phosphate solubilizing microorganisms to compare with control treatment. The result shows that the solubilizing index ranged between 1.4 to 1.6 for isolated microorganisms, the decrease in soil pH which has an enormous influence on phosphate solubility were significantly influenced by the addition of phosphate solubilizing microorganisms, and manure is 6.5 pH comparing with 8 pH for control. Soil soluble and extractable phosphorous also increased by a combination of phosphate solubilizing microorganisms and manure recording 0.46±0.03 ppm and 10.7±1.01 ppm respectively comparing to 0.39±0.01 ppm and 0.75±0.11ppm for control after one month of the experiment, and this significance continued to 3 and 5 months after planting followed by the combination treatment of rock phosphate and phosphate solubilizing microorganisms. Total phosphorous in both wheat shoot and root after 5 months of planting were increased significantly by the addition of phosphate solubilizing microorganisms and manure to record 0.792±0.11% in shoot and 0.66±0.13% in roots and more than other treatments, however the translocation of phosphorous is harder than nitrogen from roots to shoots. The addition of phosphate solubilizing microorganisms enhanced the growth ratio of wheat up to 96±5 comparing to 40±3 for control.

Cyanophage Distribution Across European Lakes of the Temperate-Humid Continental Climate Zone Assessed Using PCR-based Genetic Markers

Studies of the diversity and distribution of freshwater cyanophages are generally limited to the small geographical areas, in many cases including only one or few lakes. Data from dozens of various lakes distributed at a larger distance are necessary to understand their spatial distribution and sensitivity to biotic and abiotic factors. Thus, the objective of this study was to analyze the diversity and distribution of cyanophages within the infected cells using marker genes (psbA, nblA, and g91) in 21 Polish and Lithuanian lakes. Physicochemical factors that might be related to them were also analyzed. The results demonstrated that genetic markers representing cyanophages were observed in most lakes studied. The frequently detected gene was psbA with 88% of cyanophage-positive samples, while nblA and g91 were found in approximately 50% of lakes. The DNA sequences analyses for each gene demonstrated low variability between them. Although, the psbA sequences branched within the larger cluster of marine Synechoccocuss counterparts. The principal component analysis allowed to identify significant variation between the lakes that presented high and low cyanobacterial biomass. The lakes with high cyanobacterial biomass were further separated by country and the different diversity of cyanobacteria species, particularly Planktothrix agardhii was dominant in the Polish lakes and Planktolyngbya limnetica in the Lithuanian lakes. The total phosphorous and the presence of cyanophage genes psbA and nblA were the most important factors that allowed differentiation for the Polish lakes, while the pH and the genes g91 and nblA for the Lithuanian lakes.