Aquatic Biomass Research Articles

Characterization of saline groundwater resource quality for aquatic biomass production: A statistically-based approach

A study was conducted to determine if the saline groundwaters of New Mexico could be statistically reduced to a few major types based on ionic composition. A decreased number of water types could then be used to screen candidate microalgal strains for tolerance to various environmental conditions and for biomass production potential. Two major water types were identified, both with average salinities of 4000 mg l −1 TDS. Type I water had a much higher divalent ion concentration than Type II water and was dominated by Na + , C1 − , Mg 2+ , and Ca 2+ . The major ions in Type II water were Na + , Cl − , SO 4 2− , and HCO 3 − . The relative ionic composition of the two water types that were derived from the analysis of saline groundwater were also representative of the ionic composition of the saline surface waters of the southwestern United States. The growth rates of several microalgal strians were measured in the two water types over a range of temperatures (10–35°C) and conductivities (10–70 mmho cm −1 ). The algae exhibited a wide range of growth responses to the water types indicating the importance of screening the strains with waters which would be available for biomass production.

Long-chain alkanediols: biological markers for cyanobacterial contributions to sediments.

One significant family of sedimentary lipids of widespread occurrence are series of C28-C32 alkanediols and hydroxyketones. The recognition of the same series of alkanediols as major lipid components of a field population of the cyanobacterium Aphanizomenon flos-aquae leads us to propose that these lipids are markers for cyanobacterial inputs to sediments. The frequency of occurrence of the alkanediols in sedimentary environments supports the recent finding that cyanobacteria are major contributors to the aquatic biomass.

Economic assessment of biomass feedstocks for the chemical industry

New sources of raw materials and new technology must compete against the established chemical industry. This competition is assessed by an industry-wide analysis of all of the hundreds of processes and feedstocks that compose the chemical industry. We use a linear programming model of the industry to determine conditions under which aquatic biomass, algae, corn, corn stover, glucose, kelp, molasses, municipal solid waste, sugar beet, sugar cane, wheat straw, lignin and wood can compete as chemical feedstocks with petroleum, natural gas and coal. Of the several sources studied, wood seems to be the most attractive biomass feedstock.

Purification of Pisciculture Waters through Cultivation and Harvesting of Aquatic Biomass

The study of thermal wastes from the nuclear plants around Pierrelatte for agricultural, piscicultural, energy and environmental protection purposes resulted in the establishment of a pilot facility as early as 1976. An aquatic macrophyte pilot facility has been operational since 1983 to study the use of water hyacinths from the aspects of energy and ecology. The results obtained suggest that production yields for the 7 month growing period should exceed 60 metric tons (MT) (dry weight) per hectare in a European climate, and that such crops can feasibly be cultivated in temperate regions. The pilot facility is supplied with pisciculture effluent water, making it possible to quantify the stabilization power of the plants. Without primary decantation, with a retention time of 4 days and stabilization with water hyacinths only, the organic matter waste pond surface area required is 3.5 m2/m2 of pisciculture pond. Any primary or secondary facilities will lead to a reduction of these areas. The final decision will depend on the economical optimization of all the wastewater.

Energy from biomass and wastes: 1985 update and review

The gradual and then rapid reduction of crude oil prices, the impact of U.S. Gramm-Rudman-Hollings legislation (to reduce budget deficits) on R&D (research and development) budgets, the partial elimination of renewable-energy tax credits, and the possible elimination of all energy tax credits and forgiveness via tax reform, are all taking their toll on energy research and commercialization ventures. However, it appears that “biofuels” will survive and continue to exhibit modest increases in contributions to primary energy demand. A comprehensive assessment of renewable-technology options has shown that biofuels is the only option capable of making significant contributions to all energy sectors. The total contribution of renewable energy to primary energy demand in the U.S.A. is about 7.2EJ/y (6.8 quad/y); biofuels provide about 40% of the total. Research on short-rotation intensive-culture (SRIC) trees and herbaceous and aquatic biomass has identified specific species for development. Some of these species appear to be near economic feasibility as energy crops now. Commercialization of biomass and waste combustion systems has shown a spurt in growth because of the business opportunities offered by laws encouraging cogeneration. Thermochemical gasification research on advanced technology systems has reached the point where scale-up is being considered. Commercialization of state-ofthe-art technologies has slowed, but applications for small-scale producer gasifiers, particularly in developing countries, continue to expand. Thermochemical liquefaction research has concentrated mainly on high-temperature pyrolytic conversion methods that can increase yields and selectivities. Significant research achievements have been made in anaerobic digestion, but whatever its future as a large-scale source of methane, it is clear that digestion capacity will have to increase many-fold before biological methane can attain its potential. The mandated reduction in lead content of gasolines presents substantial marketing opportunities to alcohol-fuel producers. If projections for ethanol-fuel markets materialize, conversion of low-cost lignocellulosic materials will be necessary. Research to develop this technology is now in progress.

A review of the technological feasibility of aquacultures for municipal wastewater treatment

The technical feasibility of utilising aquacultures for municipal wastewater treatment is reviewed. Aquacultures containing one or more aquatic weeds are cost effective for secondary and tertiary wastewater treatment, compared to the highly energy intensive conventional secondary and tertiary wastewater treatment systems. The major advantages are less capital and maintenance costs required as opposed to conventional wastewater treatment. Aquatic treatment systems utilising one or two aquatic weeds are efficient in substantial removal of phosphorus and nitrogen from the wastewater compared to the conventional secondary and tertiary wastewater treatment systems. Further, biogas generated from the harvested aquatic weed biomass could meet the treatment costs of the aquatic treatment systems utilising these aquatic weeds. Year round treatment of municipal wastewater utilising these aquatic weeds is possible even in the temperate regions of the world by housing the treatment systems in green houses. Other aqua...

Macrophyte Growth in Shallow Streams: Field Investigations

Three contrasting segments of a stream, exhibiting varying levels of production, were monitored for water quality, oxygen-derived primary productivity and the yield and growth rate of indigenous aquatic plant biomass. Average daily primary productivity rates observed for the respective segments included: 3.9 g O2/sq m/day for a low in-stream phosphorus (22 micrograms total P/L), periphyton-dominated community; 5.5 g O2/sq m/day for a low in-stream phosphorus (17 micrograms total P/L) mixed periphyton-macrophyte community; 18.3 g O2/sq m/day for an enriched phosphorus (1,340 micrograms total P/L) macrophyte-dominated community. Additional data are presented for sediment and interstitial sediment water nutrients and macrophyte biomass variations over a growing season. Specific photosynthetic rates estimated for the macrophyte population ranged from 0.005/day to 0.244/day for the low phosphorus environment to from 0.036/day to 0.456/day for the phosphorus-impacted segment. The need to accomodate natural and wastewater-derived in-stream aquatic plant productivity in wasteload allocation analysis is discussed.

Environmental contamination in the oil fields of western Pennsylvania

The effects on freshwater wildlife of chronic exposure to oil field discharges are not well known. Collections of wastewater, aquatic invertebrates, fish, salamanders, and small mammals were made in several streams in the oil fields of western Pennsylvania during 1980-81. Estimates of the petroleum content of two wastewater discharges were high (21.9 and 8.4 ppm) and one was low (0.3 ppm). Water conductivity was inversely related to aquatic invertebrate biomass. Hydrocarbons, accumulated in significantly greater amounts in crayfish, fish, and small mammals from collection sites with oil extraction activity than from sites without oil extraction activity. Estimates of total petroleum in invertebrates, trout, and suckers averaged between 200 and 280 ppm for oil extraction sites and between 8 and 80 ppm for sites without oil extraction activity. Oil extraction activity did not affect metal accumulation by fish. Oil and wastewater discharges in oil fields disrupt community composition and can cause an overall reduction in stream productivity.

Hemicellulose conversion by anaerobic digestion

This research was undertaken to study the digestibility of the hemicellulose fractions of an aquatic biomass, a land-based biomass and a biomass-waste blend under various fermentation conditions. The conversion of hemicellulose was higher than those of cellulose and protein under the mesophilic condition. Hemicellulose was converted at a much lower efficiency than cellulose during thermophilic digestion. In contrast, cellulose conversion was about the same under mesophilic and thermophilic conditions. Cellulose was utilized in preference to hemicellulose during mesophilic fermentation of nitrogen-supplemented Bermuda grass. It was speculated that Bermuda grass cellulose was converted at a higher efficiency than hemicellulose in the pressure of external nitrogen because the metabolism of the breakdown product (glucose) of cellulose requires the least investment of enzymes and energy.

Pesticide Manipulation of a Headwater Stream: Invertebrate Responses and Their Significance for Ecosystem Processes

The influence of macroinvertebrates on detrital processing was evaluated by excluding them from one of two small southern Appalachian streams. Exclusion in the treated stream was accomplished by periodic applications of 10 ppm of the insecticide methoxychlor. This caused massive invertebrate drift (>12,000 organisms/m3 of discharge) during the initial treatment and reduced aquatic insect densities and biomass to <10% of the levels within the adjacent untreated reference stream. Community structure in the treated stream shifted from a system dominated by small numbers of large shredding insects (e.g., Peltoperla, Pycnopsyche, Tipula) with comparatively low reproductive rates, to one dominated by large numbers of small collector-gatherers and predators (e.g., Oligochaeta, Chironomidae, Turbellaria) with high reproductive rates. Non-insect invertebrate biomass and density became significantly higher in the treated stream than in the reference stream following initial methoxychlor treatment. We interpreted th...

Influence of Field Environment and Fertilizer Management on Ammonia Loss from Flooded Rice

AbstractThe importance of ammonia volatilization after urea application to flooded rice (Oryza sativa L.) was assessed in six experiments at two field locations in the Philippines, using a nondisturbing micrometeorological technique. Earlier studies had produced conflicting results probably because the techniques used did not conserve the balance of physical, chemical, and biological processes that affect ammonia loss in this ecosystem. Urea was either broadcast and incorporated immediately before transplanting of rice seedlings (BI treatments) or broadcast into the floodwater 14 or 21 d after transplanting (AT treatments) and 5 to 7 d before panicle initiation (PI treatments). Ammonia volatilization proceeded rapidly and continued for 6 to 10 d after urea was applied. In the AT treatments, NH3 loss accounted for 47% and 27% of the urea‐N applied. Ammonia loss showed pronounced diurnal fluctuations that were synchronized with fluctuations in floodwater pH, between maxima of 8.6 to 9.0 at 1200 to 1400 h and minima of 7.8 to 8.0 at 0500 to 0600 h in the AT experiments. Floodwater pH in nonfertilized areas showed similar trends, indicating that fertilizer addition was not the prime cause of the pH fluctuations. Ammoniacal N in the floodwater accumulated to ≃ 14 g m−3 in the AT studies, but the concentrations decreased during daytime and increased again at night, with a net loss of ammonia during the day. Differences in wind speed appeared to account for most of the difference in NH3 loss observed between the AT treatments. Rates of ammonia loss (10–15%) were lower when urea was applied at a later growth stage (PI), even though floodwater ammoniacal N again rose to 13 g m−3. In contrast to the AT studies, floodwater pH at PI did not exceed 8.0 to 8.3. Apparently, shading of the floodwater by the rice canopy lowered the photosynthetic activity of the aquatic biomass and thus reduced the degree of CO2 depletion and the potential for NH3 loss. Ammonia volatilization loss after urea incorporation (BI treatment) accounted for only 13% of the N applied at Los Baños. This sharp reduction in loss, compared with those after AT applications, was largely due to lower floodwater urea and ammoniacal N concentrations from 2 days after application in a system where urea was largely incorporated into the soil.

Energy from Biomass and Wastes

Some of the technological developments discussed at a symposium on biomass and wastes are presented. Evidence indicates that combustion processes fed with biomass and wastes can form dioxins, but these hazards seem to be minimal. Biomass production is discussed in relation to tree rotation and herbaceous crops. Research on production of aquatic biomass has concentrated on microalgae. Wood combustion technology is discussed for both residential, industrial, and utility applicatons and municipal solid waste. Research on anaerobic digestion is evaluated. Many commercial systems have been installed by industry and farm owners for combined waste treatment-energy recovery applications. One approach to natural production of liquid fuels by biomass combines photosynthesis and gene manipulation.

Probing the feasibility of large scale aquatic biomass energy farms

Researchers from industry, universities and research organizations are probing the economic and bioengineering feasibility of large-scale open ocean and land-based aquatic energy farming. Innovative design concepts, coupled with advances in this still primitive technology, may one day make aquatic biomass production a cost-effective supplementary source of energy. Before that can happen, however, there are perplexing bioengineering problems, and legal and environmental obstacles to be overcome. Rather than seeking definitive answers and solutions, this note raises and defines questions that need to be addressed and examines the considerations and tradeoffs that need to be weighed before deciding to what extent aquatic biomass systems merit inclusion in a solar energy program.

Methane fermentation of aquatic biomass

Four aquatic biomass species were anaerobically fermented to methane as part of an evaluation of these biomass as potential energy resources. Two freshwater weeds (Duckweed ( Lemna sp.) and Hydrilla verticillata) and two marine algae ( Gracilaria ceae and Ulva lactuca) were evaluated. Volatile solids, ash content, calorific values, and elemental analyses are reported for these biomass. All four were fermented at mesophilic (37°C) conditions in 50 1 CSTR units using a rich nutrient feed of essentially equal parts by weight sewage sludge and aquatic biomass in an approximately 5% solids concentration slurry and with a 26-day retention time. In addition, the two freshwater weeds were evaluated in a similar manner at thermophilic (60°C) conditions. Bioconversion efficiency was based on measured energy out, as methane, and measured energy in, as calorific values of the biomass. It was found that 25 to 34% of the energy value in the freshwater weeds was recovered at mesophilic conditions, a low value perhaps due to the fact that steady-state conditions were not reached in the fermenters. For the marine species, 27 to 45% of the energy value was recovered under the same conditions. Conversion of the freshwater weeds at thermophilic conditions, however, was from 32 to 46%. It was found that by assuming all total volatile solids in the seaweed had an oxidation state equivalent to cellulose the same bioconversion efficiency was obtained as measured directly, appearing to indicate a high fraction of biodegradable polysaccharides. Freshwater weeds, however, demonstrated a much lower conversion based on calorimetric values than with the assumption that all volatile material was cellulosic in nature. This may indicate that bioconversion of a cellulosic fraction occurred, but that residual higher energy components in the biomass such as lignin were nonbiodegradable under these conditions. Results of the bioconversion of alkaline pretreated (saturated lime) Duckweed were approximately equal to those with the untreated biomass. An inhibition investigation to explain lower than anticipated bioconversion was conducted on the two marine species based on their high degree of sulfonation of polysaccharides. This hypothesis proved to be invalid, and slow acclimatization of innoculating microorganisms was given as a possible explanation of observed results. Further, in situ or batch fermentation were carried out at mesophilic conditions using minimal inoculum. Both freshwater aquatic biomass were evaluated in 2 1 units, while Hydrilla was also evaluated in a 50 1 unit. It was found that 80% of the methane was evolved in the first two months of operation. Moreover, bioconversion performance in these simple mesophilic in situ units were equal to that in the CSTR units at thermophilic conditions, namely 34–46% conversion. Obtaining baseline biomass conversion results in simple in situ units appears most practical. Pretreatment alternatives and novel processing techniques which improve on conventional CSTR technology appear to be required to improve bioconversion energy efficiencies.