Ammonia removal from compost leachate using zeolite. II. A study using continuous flow packed columns

A review on the application of nanoporous zeolite for sanitary landfill leachate treatment

This review deals with low-cost nanoporous zeolites for the treatment of sanitary landfill leachate. Organic contaminants and ammoniacal nitrogen are significant parameters in landfill leachate treatment. Adsorption processes are regarded as promising alternative treatment options in this respect. Zeolites are aluminosilicate materials that are widely used in separation, filtration, adsorption and catalysis. Natural zeolite is a low-cost and readily available form of zeolite and is a promising candidate to be used as an ion-exchange material for ammonia and other inorganic pollutant removal from landfill leachate. In this review, adsorption isotherms and kinetic models in batch systems are evaluated and adsorption design parameters of the fixed-bed system are presented. Studies on ammonia removal from landfill leachate via zeolites have been thoroughly investigated. Leachate treatment systems combined with zeolites are presented. Cost of zeolites are also reported in comparison with other adsorbents. The investigated studies demonstrate that activated zeolite can improve the removal of chemical oxygen demand, NH₃-N and colour significantly compared to the case where raw zeolite is used. Moreover, the composite of activated carbon and zeolite is also favorable for ammonia removal according to reported findings, where best adsorptive removal is attained on the composite media (24.39 mg/g).

Nitrification of leachates from manure composting under field conditions and their use in horticulture

This work aimed to demonstrate the feasibility of nitrification applied to the treatment of leachates formed during composting of cattle and pig manure in order to promote their further use as liquid fertilizer in horticulture. Nitrification trials were successfully conducted in summer and winter seasons under Mediterranean climate conditions. Subsequently, effect of using the nitrified effluents as nutritive solution in the fertigation of lettuce (Lactuca sativa L.) was assessed in terms of productivity and nutrient uptake. Similar productivities were obtained when using the nitrified effluents and a standard nutritive solution. However, results also evidenced high nutrient uptake, which indicates that dosage should be adjusted to culture requirements.

Membrane bioreactor technology: a novel approach to the treatment of compost leachate

Compost leachate forms during the composting process of organic material. It is rich in oxidizable organics, ammonia and metals, which pose a risk to the environment if released without proper treatment. An innovative method based on the membrane bioreactor (MBR) technology was developed to treat compost leachate over 39days. Water quality parameters, such as pH, dissolved oxygen, ammonia, nitrate, nitrite and chemical oxygen demand (COD) were measured daily. Concentrations of caffeine and metals were measured over the course of the experiment using gas chromatography - mass spectrometry (GC/MS) and inductively coupled plasma - mass spectrometry (ICP-MS) respectively. A decrease of more than 99% was achieved for a COD of 116g/L in the initial leachate. Ammonia was decreased from 2720mg/L to 0.046mg/L, while the nitrate concentration in the effluent rose to 710mg/L. The bacteria in the MBR system adjusted to the presence of the leachate, and increased 4 orders of magnitude. Heavy metals were removed by at least 82.7% except copper. These successful results demonstrated the membrane bioreactor technology is feasible, efficient method for the treatment of compost leachate.

Full scale performance of compost's leachate treatment by biological anaerobic reactors

A wide range of treatment processes have been applied to leachate treatment with varying success. The aim of this research was to examine the performance of two hybrid biological anaerobic reactors in a new full-scale leachate treatment plant in Rasht composting facility, north of Iran. The studied plant was operated for nearly 12 months and treated up to 50 m(3) day(-1) of fresh compost leachate with a relatively high BOD(5) to COD ratio of around 0.5. The average COD of the raw leachate was measured to be 81 000 mg L(-1). 30% of effective volume of each reactor was filled with clay blocks with a specific area of 87 m(2) m(-3) as the fixed bed. The sequencing of reactors was down flow and up flow, respectively. The maximum COD removal efficiency of 91% was achieved with 4.5 kg COD m(-3 )day(-1) of organic loading rate and 7500 mg L(-1) of volatile suspended solids. There was no significant difference in COD removal efficiency when the reactors were operated with an organic load between 2 and 5 kg COD m(-3 )day(-1). Increasing the volumetric organic loading rate to greater than 6 kg COD m(-3 )day(-1) caused a considerable reduction of COD removal efficiency. The COD removal efficiency decreased to less than 70% when the organic load rose to 10.8 kg COD m(-3 )day(-1). Nevertheless, hybrid anaerobic reactors proved to be a feasible technique for the reduction of organic load from the composting leachate which was the subject of this study.

Bioremediation of leachate from a green waste composting facility using waste-derived filter media

The evaluation of two waste-derived materials used to treat compost leachate by biofiltration is described in this paper. Nine biofilters were constructed using 240 l, high density polyethylene containers. Three containers were filled without compaction with 200l of each of three types of filter media. Waste-derived filter media (compost and oversize) were compared to a mineral control (granite chips). The filters were fed with compost leachate from a typical green waste composting facility at hydraulic loading rates ranging from 0.05 m3/m3/day to 0.5 m3/m3/day over a period of twelve months. The oversize medium emerged as the most effective demonstrating characteristics of consistency of effluent quality and resilience to stress. The oversize medium produced an effluent of <10mg/l ammoniacal nitrogen on >95% of sampling occasions. The organic component of compost leachate was dominated by compounds that proved to be recalcitrant to biodegradation. The solids content of the treated effluent remained too high to be acceptable for direct discharge to a watercourse without further treatment and if discharge to a watercourse is to be considered, a polishing stage (e.g., reed bed) able to remove solids and dampen occasional peaks of ammoniacal nitrogen should be employed.

P-nitrosodimethylaniline (RNO)-based evaluation of enhanced oxidative potential during electrochemical treatment of high-salinity wastewater

The electrochemical bleaching of p-nitrosodimethylaniline (RNO) was investigated in order to apply its reactions to evaluating electrochemical oxidation. The bleaching rate of RNO during electrochemical treatment was accelerated by the presence of chloride ions. The initial bleaching rate of RNO was found to be accelerated during the electrolysis of NH4Cl, suggesting that electrochemically generated chloramines are sufficiently strong oxidants to convert RNO. A method of evaluating direct or indirect oxidative potential for electrochemical treatment was proposed, provided that the initial bleaching rate of RNO is consistent with low concentrations of RNO. The saline wastewater of Japanese pickle production processes (brown mustard and Japanese radish) was electrochemically treated. The ammonium ion (18 and 8 mg L(-1)) was almost completely removed after 1 h of treatment in the presence of NaCl (3%). The removal rate of total organic carbon (TOC) exceeded 90% for 7mgL(-1) and 60% for 352mgL(-1), indicating that electrochemical treatment is useful in removing ammonium ions and organic substances from high-salinity wastewater.