Long-term performance of side-stream deammonification in a continuous flow granular-activated sludge process for nitrogen removal from high ammonium wastewater.

An innovative granular sludge deammonification system was incorporated into a conventional-activated sludge process. The process incorporated an internal baffle in the bioreactor for continuous separation of granular biomass from flocculent biomass, which allowed for controlling the solids retention time of flocculent sludge. The process was evaluated for ammonium removal from municipal digested sludge dewatering centrate under various operating conditions lasting over 450 days.

Rare taxa have potential to make metabolic contributions in enhanced biological phosphorus removal ecosystems.

Enhanced biological phosphorus removal (EBPR) relies on diverse but specialized microbial communities to mediate the cycling and ultimate removal of phosphorus from municipal wastewaters. However, little is known about microbial activity and dynamics in relation to process fluctuations in EBPR ecosystems. Here, we monitored temporal changes in microbial community structure and potential activity across each bioreactor zone in a pilot-scale EBPR treatment plant by examining the ratio of small subunit ribosomal RNA (SSU rRNA) to SSU rRNA gene (rDNA) over a 120 day study period.

Recovery of phosphorus from dairy manure: a pilot-scale study.

Phosphorus was recovered from dairy manure via a microwave-enhanced advanced oxidation process (MW/H2O2-AOP) followed by struvite crystallization in a pilot-scale continuous flow operation. Soluble phosphorus in dairy manure increased by over 50% after the MW/H2O2-AOP, and the settleability of suspended solids was greatly improved. More than 50% of clear supernatant was obtained after microwave treatment, and the maximum volume of supernatant was obtained at a hydrogen peroxide dosage of 0.

Modeling phosphorus removal and recovery from anaerobic digester supernatant through struvite crystallization in a fluidized bed reactor.

The cost associated with the disposal of phosphate-rich sludge, the stringent regulations to limit phosphate discharge into aquatic environments, and resource shortages resulting from limited phosphorus rock reserves, have diverted attention to phosphorus recovery in the form of struvite (MAP: MgNH4PO4·6H2O) crystals, which can essentially be used as a slow release fertilizer. Fluidized-bed crystallization is one of the most efficient unit processes used in struvite crystallization from wastewater. In this study, a comprehensive mathematical model, incorporating solution thermodynamics, struvite precipitation kinetics and reactor hydrodynamics, was developed to illustrate phosphorus depletion through struvite crystal growth in a continuous, fluidized-bed crystallizer.

Effects of microwave, ultrasonic and enzymatic treatment on chemical and physical properties of waste-activated sludge.

The effects of microwave irradiation, microwave enhanced advanced oxidation process (MW/H2O2-AOP), ultrasonic and/or protease enzymatic treatments on chemical and physical properties of waste-activated sludge were studied. The different treatment mechanisms resulted in various degrees of biomass cell destruction and nutrient release, as evidenced by transformation of chemical constituents, particle size distribution, and scanning electron microscopic imaging. The microwave irradiation and the MW/H2O2-AOP resulted in higher soluble protein concentrations, but lower amino acids.

Determining the feasibility of phosphorus recovery as struvite from filter press centrate in a secondary wastewater treatment plant.

In this study, the workability of a pilot-scale, fluidized reactor was examined to determine effectiveness in removing, and recovering, phosphorus as struvite, from centrate at Lulu Island Wastewater Treatment Plant (LIWWTP), Richmond, British Columbia. The crystallization process was run continuously over a period of 5 months in two runs (Run 1 for 4 months and Run 2 for a month). In addition to efficient recovery of phosphorus as struvite, the study also investigated factors that affect the growth of struvite.

Real-time treatment of dairy manure: implications of oxidation reduction potential regimes to nutrient management strategies.

A pilot-scale sequencing batch reactor (SBR) was operated at a dairy farm to test real-time based control in winter operation conditions. A combination of high loading and low oxidation reduction potential (ORP) conditions in the aerobic stage of SBR treatment (an end value of -50 to -150 mV) inhibited nitrification while maintaining carbon removal. After a period of over-aeration over several cycles, the ORP at the end of the aerobic stage increased to values of 50-75 mV.

Dairy manure treatment, digestion and nutrient recovery as a phosphate fertilizer.

A combined approach of biological treatment, solids digestion and nutrient recovery was tested on dairy manure. A sequencing batch reactor (SBR) was operated in three modes, in order to optimize nutrient (nitrogen and phosphorus) removals. The highest average removal efficiencies of 91% for NH4-N, 59% for PO4-P and 80% for total chemical oxygen demand (COD) were achieved.

A simple method to estimate the contribution of biological floc and reactor-solution to mass transfer of oxygen in activated sludge processes.

In this study, the mass transfer coefficient of biological floc (K(L)a(bf)) was estimated from the mass transfer coefficient of the mixed-liquor (K(L)a(f)) and the reactor-solution (K(L)a(e)). The biological floc resistance (BFR) and reactor-solution resistance (SR) were defined as the reciprocal of K(L)a(bf) and K(L)a(e), respectively, by applying the concept of serial-resistance originally presented in two-film theory (Lewis and Whitman (1924) Ind Eng Chem 16:1215-1220). The specific biological floc resistance (SBFR) was defined as biological floc resistance per unit biomass concentration.

The impact of influent nutrient ratios and biochemical reactions on oxygen transfer in an EBPR process--a theoretical explanation.

In this investigation, a laboratory-scale enhanced biological phosphorus removal (EBPR) process was operated under controlled conditions to study the impact of varying the influent ratio of chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP), and the consequential biochemical reactions on oxygen transfer parameters. The data showed that the experiment with high influent phosphorus relative to nitrogen (COD/TP = 51 and TKN/TP = 3.1) achieved higher alpha and oxygen transfer efficiency (OTE(f)).

The effects of magnesium and ammonium additions on phosphate recovery from greenhouse wastewater.

Phosphorus recovery from greenhouse wastewater, using precipitation-crystallization, was conducted under three levels of calcium concentration, 304 mg/L (7.6 mmol/L), 384 mg/L (9.6 mmol/L), and 480 mg/L (12 mmol/L), and also with additions of ammonium and magnesium into the wastewater.

Methanol-induced biological nutrient removal kinetics in a full-scale sequencing batch reactor.

The primary goal of this research was to determine the potential for denitrification and phosphorus removal of a full-scale sequencing batch reactor (SBR), with and without the use of methanol as an external carbon source. The control SBR, without methanol addition, achieved negligible denitrification. Two denitrification rates were observed in the experimental SBR, with methanol addition, an initial fast rate and a slower second rate.