Primary Pond Research Articles

Impact of soil and water quality on the sustainable management of mangrove-compatible brackishwater aquaculture practices in Indonesia

The widespread degradation of mangroves has been attributed to their conversion into other land uses and purposes, most notably their destruction to construct extensive brackishwater aquaculture ponds. This study investigated the relationship between environmental factors and management alternatives for an integrated mangrove-aquaculture system in Derawan Island District, Berau Regency, East Kalimantan Province, Indonesia. The study collected a total of 56 soil and water samples from around 50 ha to assess environmental limiting factors for integrated mangrove-brackishwater aquaculture management. The measured soil quality variables included field pH (pHF), pH of hydrogen peroxide extract (pHFOX), peroxide oxidizable sulfur (SPOS), pyrite (FeS2), organic matter (OM), nitrogen-total (N-TOT), iron (Fe), and aluminum (Al). Water quality variables included salinity, temperature, pH, dissolved oxygen (DO), different forms of nitrogen (NH3–ammonia, NO3–nitrate, and NO2–nitrite), phosphate (PO4), Fe, and total organic matter (TOM). The study employed a hydrological restoration approach to suggest a mangrove-friendly aquaculture pond design and layout. The study generally showed that Acid Sulfate Soils (ASS) significantly restricted the existing mixed-mangrove aquaculture pond management by negatively impacting water quality. This study highlights that, given the characteristics of ASS-affected aquaculture ponds, reducing pond size for shrimp culture (mangrove-to-pond ratio of 80% and 20%) will simplify managing ASS environmental limiting factors through cost-effective remediation techniques and a Balanced Fertilization Strategy (BFS). The reduced shrimp pond size will also provide direct opportunities for mangrove restoration and allow effective hydrological restoration. The economic benefit of the proposed pond design and management model focuses on diversifying production units which include shrimp aquaculture ponds, milkfish or tilapia culture in the peripheral canals of the mangrove compartment, juvenile shrimp production, and periodic harvest from the primary pond canal. The study findings are particularly applicable to ponds that have already been built in ASS to improve productivity in addition to supporting the mangrove rehabilitation program. Converting mangrove and ASS-affected land is not advisable for constructing new aquaculture ponds.

Experience in locating leaks in geomembrane-lined ponds

This study presents the results of five years of applying the dipole method in geomembrane-lined ponds to locate leaks arising from either the construction or operational stage. Inspections were conducted on 136 projects designed with single (n=57) or double (n=79) liner and located in the United States (n=108), Mexico (n=5), or Canada (n=23). The ponds were tested either full or at a depth between 0.3m and 0.8m, both sets of results were compared to the available literature. Approximately 210 ha of primary geomembrane-lined ponds were surveyed, uncovering 825 leaks during the study period. An average number of leaks/ha was 13.2 ranging from 0 to 272. The highest results were 272, 242, and 131 leaks/ha in double-lined, and 80 and 77 leaks/ha in single-lined ponds. The inspected data revealed that 43% of projects had 0-2 leaks/ha, 20% had >2-5 leaks/ha, 14% had >5-10 leaks/ha, and 16% of the ponds had >20 leaks/ha. The results of this study are crucial for designers, Landfill Operators, and Environmental Agencies in establishing inspection practiced for lined ponds, particularly after a period of operation.

Seasonal Species Diversity and Dominance of Phytoplankton in Different types of tropical Domestic Sewage Oxidation Ponds

Planktons are small microscopic organisms, comprising diatoms and algae, which form the basis of primary production and the zooplankton, which are mainly crustaceans, rotifers and larval stages of larger animals. Both are the bio-indicators of a water body, constituting the main food for the carnivorous and omnivorous fishes in any aquatic ecosystem. In the present study, the species diversity, and their abundance with a total and average population of various species of phytoplankton have been studied in the primary and secondary domestic oxidation ponds along with a freshwater control pond situated at Shahpura. Bhopal, Madhya Pradesh, India. Physicochemical parameters like light penetration, water temperature, pH and DO were also analyzed along with the phytoplankton population in both types of ponds to assess their impacts. The samples were collected and identified using standard methods. The results revealed that the phytoplankton groups like Chlorophyceae, Bacillariophyceae, Cyanophyceae and Euglenophyceae were dominantly found in the sewage oxidation ponds along with about 20 species of phytoplankton in varying population densities in different seasons. A similar analysis was done in a freshwater control normal pond for comparison. Physicochemical parameters in these secondary sewage oxidation ponds with a high nutrient load were found to be highly favourable for the growth of the plankton species. A comparatively low number of phytoplankton was recorded in the freshwater control pond, which was highly deficient in nutrients.

The use of multi-sensor satellite imagery to analyze flood events and land cover changes using change detection and machine learning techniques in the Barito watershed

Indonesia is one of the countries in the world that is frequently affected by floods. Flood disasters can have various negative impacts and therefore need to be analyzed to determine prevention and mitigation measures. This study examined land cover change, flood detection, and flood distribution using multitemporal Sentinel-1 and Landsat-8 satellite imagery in the Barito watershed. A combination of change detection and the application of the Otsu algorithm was used to detect floodplains from Sentinel-1 imagery. Land use/land cover (LULC) changes are detected using a combination of change detection and machine learning in the form of a random forest algorithm. The overlay technique was used to analyze the distribution of floodplains. In this study, the floodplain in the study area was mapped to 109,623 ha. The change detection method detects a decrease in the areas of primary forest, secondary forest, fields, rice fields, shrubs and ponds, respectively, by 13,020 ha, 116,235 ha, 259 ha, 146,696 ha, 47,308 ha, and 9,601 ha. Settlements, bare land, plantations and water bodies increase by 14,879 ha, 64,830 ha, 218,916 ha, and 34,768 ha, respectively. Flooding was mainly found in the classes of rice fields, water bodies and primary forests.

Application of bacteriophage cocktails for reducing the bacterial load of nosocomial pathogens in hospital wastewater.

In the third world and developing countries, hospital sewage is mixed with municipal wastewater. The treated effluent contains dangerous bacteria released into the environment and used in the irrigation of agricultural products, and eventually these bacteria may endanger the human health through foods. Antibiotic-resistant bacteria are mostly found in hospital wastewater. In water and wastewater treatment plants, large amounts of toxic and polluting substances are removed and destroyed, but this process does not eliminate bacteria. Wastewater samples from 22 hospitals in Iran were collected and in the meantime specific phages (against drug-resistant pathogenic bacteria) extracted using the bilayer agar technique. Phage amplification was performed by employing a fermenter after phage identification. Amplified phages were added to the primary sedimentation pond using New-Brunwick biofermenter BioFlo/Celligen®115 and the bacterial count was evaluated for the desired bacteria. Our phage cocktail was able to reduce 99.8%, 99.4%, 99.5%, 99.8%, 99.7%, 99.8%, 99.6% and 99.9% of E. coli, E. faecium, E. faecalis, K. pneumoniae, A. baumannii, P. aeruginosa, S. maltophilia and S. aureus counts respectively. The application of phage cocktails can remarkably help improve personal hygiene, the environment, and the optimization of surface water.

Identification of quality of irrigation water Danda Besar Swamp Irrigation Area in Barito Kuala District, South Kalimantan, Indonesia

Danda Besar Swamp Irrigation Area (SIA) is located in Danda Jaya Village in Rantau Badauh District, Barito Kuala Regency, South Kalimantan Province, Indonesia. It is one of tidal swamp reclamation where tidal fluctuation of Barito River affects to the hydrological condition. Danda Besar SIA has potential agricultural land about 2, 200 ha, and the productivity of paddy field was only 2 ton/ha in average for each time planting year. Two ton/ha is too low productivity due to problem of water quality in irrigation canal. However, fundamental information for the management of water quality of irrigation, monitoring data of water quality, is not measured yet. This fundamental research was conducted to identify and analyze condition of irrigation water quality. The field survey was carried out in dry months, May and June 2021 at primary canal, secondary canal, tertiary canal and pond. The final result for 6 parameters of the 4 locations (primary canal, secondary canal, tertiary canal and pond) showed there were 3 parameters (TDS, DO, and Sulfate (SO4 2-)) fulfill the class II standard, meanwhile there were 3 parameters (pH, Iron (Fe) and BOD) not fulfill the class II standard according to Government Regulation No. 22 year 2021 regarding Implementation of Environmental Protection and Management. The high content of Iron (Fe) and low content of pH recorded in all water sources should be addressed with urgency since this phenomenon as a result of pyrite oxidation affect to pH condition and may cause the low productivity of paddy field.

Effect of metal content from sewage sludge on the growth of Orthosiphon stamineus

Municipal sewage sludge can be used as fertilizer as it contains a lot of nutrients. By focusing on copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) contents in municipal sewage sludge from primary oxidation ponds and in plant tissue sections, this study attempts to explain the relationship between plant yield and metal concentrations. Raw sludge samples were collected, air-dried, and ground to powder form at the beginning of fieldwork. The metal concentrations of sewage sludge were copper 6.9 mg/kg; iron 330.2 mg/kg manganese 6.7 mg/kg and zinc 9.1 mg/kg. Orthosiphon stamineus (cat’s whiskers) was selected and the plant received a different quantity of sludge application ranging from 1 g to 4 g per plant weekly for six consecutive weeks while observations were done for eleven weeks. Physical parameters such as shrub width and height were monitored to determine plant growth. Through this study, the determined optimum sewage sludge dosage for cats’ whiskers was between 2 to 3 g per plant.

Effects of Seasonal Variation on Performance of Conventional Wastewater Treatment System

The study was to determine the seasonal differences of conventional wastewater treatment process. This was done by sampling and analyses of wastewater samples from four different points during the dry and wet seasons of the year 2019. Water samples were taken from influent point, primary effluent, trickling filter effluent and final effluent. Gravimetric method was used in determining Total Suspended Solids (TSS) and Total Dissolved Solids (TDS). The BOD 5 technique was used for determination of Biological Oxygen Demand (BOD) and the digestion method was used for determination Chemical Oxygen Demand (COD). Temperature, pH and conductivity were measured using respective meters. Analysis of Variance showed that there was significant difference (p < 0.05) in all the parameters quantified at all the points of treatment during the two seasons. The results showed that BOD and COD both reduced from one point to the next during the two seasons of study. The TSS levels increased after primary pond effluent undergoing treatment at the trickling filter and the temperature also increased after the trickling filter effluent undergoing treatment at oxidation ponds. The levels of conductivity and TDS decreased from one treatment stage to the next during dry season but during the wet season the levels of these parameters increased from one stage to the next except that the levels reduced after the primary pond effluent underwent treatment at the trickling filter. The various stages of wastewater treatment plant under were effective during the two seasons however, wet season recorded lower figures for most of the parameters. Keywords: effluent, influent, wastewater, seasonal variation, ponds DOI: 10.7176/JEES/11-7-06 Publication date: July 31 st 2021

A Study on the Applicability of Torrefied Wood Flour Natural Material Based Coagulant to Removal of Dissolved Organic Matter and Turbidity

With the emergence of abnormal climate due to the rapid industrialization, the importance of water quality management and management costs are increasing every year. In Korea, for the management of total phosphorus and total nitrogen, the major materials causing the water quality pollution, coagulants are injected in sewage treatment plants to process organic compounds. However, if the coagulant is injected in an excessive amount to PAC (Poly Aluminium Chloride), a secondary pollution problem might occur. As such, a study on the applicability of natural material-based coagulant is being conducted in Korea. Thus, this study aimed to evaluate the applicability of a mixed coagulant developed by analyzing water quality pollutants T-P, T-N as well as their turbidity, in order to derive the optimum mixing ratio between PAC and torrefied wood flour for the primary settling pond effluent. Under the condition where the content of PAC (10%) and torrefied wood flour is 1%, T-P showed the maximum removal efficiency of 92%, and T-N showed approximately 22%. This indicates that removal of T-N which includes numerous positively charged organic compounds that are equivalent to mixed coagulant is not well accomplished. Turbidity showed the removal efficiency of approximately 91%. As such, 1% of torrefied wood flour was determined to be the optimum addition. As a result of analyzing the removal efficiency for organic compounds by reducing PAC concentration to 7%, T-P showed a high maximum removal efficiency of 91%, T-N showed 32%, and turbidity showed the maximum of 90%. In addition, a coagulation process is performed by using the mixed coagulant based on 1% content of torrefied wood flour produced in this study by performing a coagulation performance comparative experiment with PAC (10%). As a result, PAC concentration was reduced to 30-50%, a similar performance with other coagulants in market was secured, PAC injection amount was reduced that an economic effect can be achieved, and it is considered to perform a stable water treatment that reduces the secondary pollution problem.

Phosphorus Characterisation of Sludge and Crust Produced by Stabilisation Ponds in a Dairy Manure Management System

In dairy farming, recirculation and continuous use of nutrients are necessary for sustainable nutrient management in both the short- and long-term. When managed effectively, nutrient recycling can improve soil fertility. On the other hand, if applied nutrients are in excess of the soil’s nutrient holding capacity, nutrients can enter surface and ground water bodies resulting in eutrophication. Phosphorus (P) characterisation in manure, pond sludge and crust, in terms of plant availability, is the first step to sustainably manage nutrients within dairy farms. In this study, pond sludge and crust were characterised for P using a sequential fractionation method. Pond sludge and crust contained significant amounts of labile P. Water extractable P (H2O-P) in primary anaerobic pond and secondary facultative pond sludges was found to be about 8 to 13 times higher than the amount found in the surface soil (0–10 cm) of a grazing paddock. Similarly, sodium bicarbonate extractable P (NaHCO3-P) in the two types of sludges was found to be about 6 times higher than in the soil. The relatively higher labile P (H2O-P and NaHCO3-P) in sludge compared to soil indicates that the sludge can be utilised as a P fertilizer on grazing pasture. In contrast, lower H2O-P compared to that of raw manure indicates that the use of sludge and crust instead of raw manure can reduce the possibility of P loss by surface runoff and leaching. Hence, it is preferable to use pond sludge and crust as fertiliser instead of raw manure.

Temporal and multi-spatial environmental drivers of duck nest survival

ABSTRACT Nest survival is determined in part by a combination of large-scale environmental factors and local nest-site characteristics. Because predation is the primary cause of nest failure, those drivers likely operate by influencing predator abundance, behavior, and/or nest detectability. For example, fluctuations in landscape productivity have the potential to alter predator and prey abundance, whereas nest vegetation and patterns of nest spacing may influence predator behavior. We used 8 yr of site-specific environmental data coupled with data collected from 11,547 duck nests to evaluate the relative importance of large-scale and local factors on nest survival. We found that higher values of gross primary productivity, basins, and pond counts were associated with higher nest survival in a given year, but were associated with lower nest survival the following 2 yr. Taken in combination with the literature, our interpretation is that productive environmental conditions can result in time-lagged increas...

Organic matter accumulation and salinity change in open water areas within a saline boreal fen in the Athabasca Oil Sands Region, Canada

Saline boreal fens represent potential models for post-mining landscape reclamation in the Athabasca Oil Sands Region (Canada) where wetland construction is challenged by salinization. One of the key indicators of reclamation success is the accumulation of organic matter within constructed fens. Thus, a better understanding of the linkages between salt content and organic matter storage in saline boreal fens can be useful for advancing fen construction in this region. As such, this study investigates how salinity fluctuations estimated by diatom-based transfer functions, coupled with changes in hydrological conditions and vegetation inferred from macrofossils have influenced organic matter accumulation rates (OMAR) over the last ~100 years in open-water areas (ponds) within a saline boreal fen near Fort McMurray, Alberta. Median OMAR (181 g m−2 yr−1) of the site suggests that the ponds situated within saline boreal fens can accumulate organic matter at a rate comparable to freshwater boreal and subarctic ponds, and the estimated salinity levels (3–21 ppt) did not severely affect organic matter accumulation. Strong significant positive (Lager Pond), strong significant negative (South Pond), and weak insignificant (Pilsner Pond) correlations between OMAR and diatom-inferred salinity were observed, suggesting that relations between organic matter accumulation and salt content are not straightforward, and salinity was not the main control on OMAR. Macrofossil data showed that organic matter accumulation has been mainly driven by water level, type of primary producers and pond regime. OMAR was the highest during the transition from peatland to ponds due to low decomposition rates resulting from high inputs of relatively resistant plant litter, and anoxic conditions. A macrophyte-dominated pond regime was associated with higher OMAR relative to algae-dominated regime.

Preliminary assessment of some physico-chemical parameters of Hanyin Danmani stream, Kaduna State, Nigeria

Preliminary determination of physico-chemical properties of Hayin Danmani stream, Igabi Local Government Area of Kaduna State, Nigeria was conducted in order to determine some physic-chemical parameters concentrations. Two different sampling stations were selected and samples were collected twice a month for three months, Nov 2015-Jan 216, along the course of Hayin Danmani stream. The mean values of pH (7.5±5.6), electrical conductivity (EC143±27.92 μs/cm), total dissolved solids (TDS 1515±54 mg/L) and turbidity (85±74.5 NTU were found to be higher than the recommended limit of World Health Organization (WHO) and Federal Environmental Protection (FEPA) with the exception of dissolved oxygen (DO, 6.5±3.4 mg/L), biochemical demand (BOD, 3±1.06 mg/L) and temperature, which were found to be in lower concentrations and within the recommended limits of FEPA and WHO respectively. The analysis of variance showed no significant difference in the months of November to January (p>0.05). The study revealed that Hayin Danmani Stream was polluted and the receiving river, the primary important streams, ponds and rivers need to be well monitored against all forms of contaminations and thus the impairment of water quality and other important aquatic organisms.Keywords: Water quality, evaluation, pollution, Hanyin Danmani Stream

Removal of orgRemoval of Organic Material in Free Water Surface Gravel Bed Filtersanic material in free water surface gravel bed filters

The removal of organic material in free surface gravel bed filters was investigatedand modelled. Two pilot wetland units of 7.5m x 1.5m x 0.7m were constructedadjacent to the University of Dar es Salaam waste stabilization ponds to receivemaximum organic and hydraulic loading rates of less than 185 kg/ha/d and 110l/m 2 /d, respectively. These units received wastewater of domestic characteristicsfrom primary stabilization pond. The entire depth of 0.7 m of the wetland unitswere packed with gravel of size 8 ~ 25 mm and porosity of 35%. Samples werecollected from the influent and effluent of wetland units and were tested forchemical oxygen demand (COD), temperature, dissolved oxygen, pH and otherparameters useful for testing of the model. A semi-empirical model representingthe major processes taking place in the wetland units was developed byincorporating suspended biomass, biofilm biomass, and sedimentation andfiltration components. The model was optimized using computer program. Themodel was successfully developed and showed that biofilm of gravel mediacontributed significantly to COD removal in wetlands.

Using stable isotope analysis to determine the contribution of naturally occurring pond biota and supplementary feed to the diet of farmed Australian freshwater crayfish, redclaw (Cherax quadricarinatus)

Nutritional requirements of redclaw (Cherax quadricarinatus) farmed in Australia are poorly understood and little is known on what is actively being consumed in semi-intensive pond culture. In this study the isotopic signatures of δ13C and δ15N of potential food sources were analysed with a multi-source mixing model to determine the extent of their contribution to the diet of farmed redclaw. Four commercial redclaw farms in North Queensland, Australia (Mareeba, Biboorha, Wondecla and Topaz) were sampled for naturally occurring pond organisms and commonly used supplemental feed such as raw corn, soybean, lupin, commercial redclaw, and chicken feed. Both naturally occurring pond biota and supplemental feed contribute to the tissue composition of redclaw to some degree. However, the contribution varies with the type of feed and availability of natural sources, for example plant material at Topaz Farm was a greater contributor with 43.9 ± 19.5 % compared to supplementary sources raw corn 8.20 ± 3.10 and lupin 1.60 ± 1.70 %. Moreover, some supplemental feeds provided a direct nutrient source for primary pond productivity; contribution of the redclaw pellet to zoo- and phytoplankton at Wondecla Farm was 83.1 ± 6.50 and 50.0 ± 9.50 %, respectively, with similarly high values for chicken feed at Biboorha Farm of 72.6 ± 4.70 and 83.4 ± 6.90 %. The cost effectiveness of such feeds needs to be questioned if these are not being consumed and utilised directly. Providing a species-specific formulated feed with improved water stability would enhance production reliability and facilitate growth within the industry.

Fluctuation of organic substances, solids, protozoan cysts, and parasite egg at different units of a wastewater integrated stabilization pond (full scale treatment plant): a case study, Iran

Appropriate treatment of wastewater and achieving desired standards are among the important objectives in wastewater treatment. The amount of organic compounds (BOD & COD), suspended solids, protozoa cysts, and parasites are different in each of these units, due to different conditions of treatment and design parameters on the stabilization pond units. The aim of this study was to determine changes of the mentioned parameters in a series of stabilization pond units in a real scale. This descriptive–analytical study was conducted on 64 samples collected in both warm and cold periods. Measurement of the parameters and parasitic analysis were done based on water and wastewater standard and Bailenger methods, respectively. Results showed no significant difference in the mean of total efficiency removal of any parameters between every two ponds with each other. Further, there was significant difference in the efficiency removal of all parameters in three ponds (anaerobic, primary, and secondary facultative), except soluble COD removal of warm season between anaerobic and primary facultative ponds, TDS of warm season between primary and secondary facultative ponds, and TDS of cold season between anaerobic and primary facultative ponds) p < 0.05). Also, changes of the trend for all the measured parameters of the system were decreasing, and efficiency removal of protozoan cysts and parasites was 100%. According to the results, it can be said that the anaerobic pond had a greater role than the facultative ponds in terms of reducing organic and parasitic parameters; but, to reach the effluent standards, a facultative pond was needed after the anaerobic pond.

Spatial distribution and community structure of phytoplankton, ciliates and zooplankton coupled to environmental factors in the Sousse saltern (Sahel of Tunisia)

The composition and distribution of the main planktonic halophilic microorganisms were studied in 12 ponds of different salinity levels, ranging from 38 to 328, in the saltern of Sousse, Tunisia, in relation to environmental factors. Nutrient concentrations increased with decreasing salinity in the ponds. Phytoplankton, ciliate and zooplankton communities were very diverse and varied spatially in relation to salinity in the ponds and to nutrient availability. Phytoplankton were dominated by diatoms, followed by dinoflagellates, in primary ponds where salinities were <100, and by the Chlorophyceae and Cyanophyceae in ponds with higher salinity. Zooplankton were dominated by copepods in the ponds of lowest salinity and by the brine shrimp Artemia salina in the most saline ponds. Within the planktonic community as a whole, diatoms, Spirotrichaea and copepods (68.9%, 89.9% and 71.05%, respectively) dominated in the lower-salinity ponds whereas Chlorophyceae, heterotrichs and Artemia salina (49.19%, 50.4% and 90%, respectively) dominated in the ponds of higher salinity. Despite the considerable constraint imposed by salinity, other environmental factors such as temperature also play a role in regulating the planktonic communities.

A survey on the ratio of effluent algal BOD concentration in primary and secondary facultative ponds to influent raw BOD concentration

It is well known that algae play an important role in treatment of municipal wastewater with facultative ponds. The objective of the present study was to determine the ratio of effluent algal BOD concentration in facultative ponds to influent BOD concentration. This descriptive analytical study was carried out on a full-scale wastewater stabilization pond system located in Islamabad Gharb, northeast Iran. A total of 138 grab samples were collected from Primary and Secondary Facultative Ponds (PFPs and SFPs) twice per month over a period of one year and analyzed for algal cell number, chlorophyll a, and BOD5 concentrations. The mean ratios of effluent algal concentration of PFP5 and SFP7 to influent BOD5 of PFP5 were 1.11±0.53 and 1.59 ± 0.66, respectively. Also, the mean ratios of effluent algal concentration of PFP6 and SFP8 to influent BOD5 of PFP6 were 1.20±0.63 and 1.57 ± 0.68, respectively. Except PFP6, significant differences were found in the means of the respective ratio in PFP5, SFP7, and SFP8 between cold and warm seasons (p < 0.05). Although there was a significant difference in the means of the respective ratio between primary and secondary facultative ponds (p < 0.05), there was no significant difference between the same ponds in modules (p > 0.05). Lower effluent algal concentration to influent BOD5 ratio found in cold months indicates strong dependency of algal photosynthetic activity to sunlight and temperature. Also, the effluent algal concentration in secondary facultative ponds was higher than that in primary facultative ponds, since better condition is provided by secondary facultative ponds for algal–bacterial activity.

Removal mechanisms of nitrogen in waste stabilization ponds

The aim of this research work was to determine the major nitrogen transformation and removal mechanisms in primary and maturation ponds. To accomplished this objective, nitrogen mass balance in waste stabilization pond system was determined using a dynamic mathematical model in order to elucidate the biological nitrogen transformation mechanisms that are effective for removal of nitrogen in this pond system. Results show that nitrogen removal efficiency in a primary facultative pond unit was 13.2%, which was largely due to net loss of organic nitrogen to sediments (9.76%) and denitrification (3.42%). On the other hand, maturation pond removed 15.2% of nitrogen received in the influent with denitrification (13.55%) being the major pathway for nitrogen removal. Ammonia volatilization was not a predominant mechanism for nitrogen removal in both primary facultative and maturation ponds. The major nitrogen transformation routes were mineralization and ammonia uptake in the primary facultative pond, but ammonia uptake by microorganisms was a predominant nitrogen transformation mechanism in maturation pond.

Use of stabilization pond sludge in cultivation of roses

One option for the increasing production of sewage sludge (SS) is its agricultural use in crops with high nutritional demand, such as the rose. Therefore, the aim of this work was to study the application of SS from primary stabilization pond in roses of the variety 'Carola'. For the experiment, the roses were planted in 20 L recipients using increasing doses of sludge (T2 - 12 Mg ha-1, T3 - 24 Mg ha-1 and T4 - 36 Mg ha-1), mineral fertilizer (T5) and control treatment (T1, without N) in a randomized block design. The evaluated parameters were: roots dry mass, aerial dry mass, total biomass, leaflets area and nitrogen concentration in the leaf. The SS application resulted in better development of the rose, increasing the roots and the aerial biomasses, the leaflets area, and nitrogen content in the leaves compared to the control (T1). There was no statistical difference between the use of mineral fertilizer (T5), and the SS under the highest dose (T4). With these benefits, the use in agriculture of sewage sludge derived from stabilization ponds proved to be an adequate option for its disposal.